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Translocations of North American prairie-grouse (genus Tympanuchus) present a conservation paradox wherein they are performed to augment, restore, or reintroduce populations, but translocated individuals exhibit a diminished ability to contribute to population restoration. For reintroduced populations without immigration, persistence can only be achieved through reproductive contributions by translocated individuals and their progeny. Due to the disruptive nature of translocation (e.g., physiological chronic stress), progeny produced at restoration sites may outperform founder populations in terms of demographics, but this hypothesis has yet to be tested. We reintroduced Columbian Sharp-tailed Grouse (T. phasianellus columbianus; CSTG) to north central Nevada from 2013 to 2017 and used integrated population models (IPMs) to evaluate the process of population establishment and estimate latent contributions of progeny hatched at the restoration site to population rate of change (). Specifically, we used annual lek (i.e. communal breeding arenas) counts and demographic data from translocated individuals to build two separate IPMs to estimate . While keeping demographic contributions by translocated individuals identical between models, one IPM assumed local progeny performance was demographically similar to translocated individuals (i.e. the baseline-IPM), and the second assumed that local progeny performed demographically similar to non-translocated CSTG (i.e. the informative-IPM). The baseline-IPM predicted strong population declines following the conclusion of translocations and extirpation by 2020, and it failed to predict observed lek counts. Conversely, the informative-IPM predicted population growth rates ( = 1.17, 95% credible interval [CI]: 0.74–1.50) that were more similar to field observations. Offspring of translocated individuals likely perform at similar levels to non-translocated populations, and by not accounting for demographic differences between translocated individuals and non-translocated progeny hatched at the restoration site, managers could underestimate population performance and persistence. Thus, translocation practices that maximize the number of offspring immediately recruited into restoration sites are likely to be the most successful. LAY SUMMARY Translocations of species of North American prairie-grouse (genus Tympanuchus) and sage-grouse (genus Centrocercus) often fail because translocated individuals experience high mortality and depressed reproduction. We translocated 215 Columbian Sharp-tailed Grouse (Tympanuchus phasianellus columbianus) as a species reintroduction project to Nevada, 2013–2017. Integrated population models (IPMs) derived solely from estimated demographic vital rates of translocated individuals fail to predict population growth and can erroneously predict population failure. Accurate predictions of population growth were achieved by modeling the non-monitored offspring cohort (of translocated individuals), hatched and reared at the restoration site using source population demographic rates. While translocated individuals exhibit diminished demographic vital rates, their offspring appear to mirror source populations. Offspring of translocated individuals constituted the core of the restored population. By maximizing the cohort of native offspring, managers can improve sage- and prairie-grouse translocation projects. We provide evidence for the process by which population restoration occurs in successful reintroduction projects.

Effective management of wildlife requires a full understanding of population dynamics and knowledge of potential drivers that influence population growth. The Ruffed Grouse (Bonasa umbellus) is a popular upland game bird widely distributed across the northern United States and Canada that has experienced population declines within portions of its range in response to forest maturation and habitat loss. Although the species has been extensively studied, few efforts have been made to synthesize demographic data into a sensitivity analysis to guide management actions. We reviewed the literature and compiled Ruffed Grouse vital rates from 14 field studies conducted across four decades (1982–2018) within the Upper Great Lakes region of Michigan, Minnesota, and Wisconsin, USA. We parameterized a deterministic matrix model to evaluate population dynamics and conducted sensitivity analyses to identify vital rates projected to have the greatest influence on the finite rate of population change (λ). Our modeling effort projected a stable but highly variable annual rate of population change (λ = 1.01; 95% CI = 0.88–1.14) for Ruffed Grouse in the Upper Great Lakes region. Stochastic rates of population change derived from spring drumming surveys (λ = 1.01; 95% CI = 0.61–1.45) and Christmas Bird Count surveys (λ = 0.99; 95% CI = 0.62–1.76) of the corresponding regional population provided validation of stable trends over the same time period as our demographic model. Prospective elasticities and variance-scaled sensitivities suggested λ would be greatly influenced by components of reproductive performance: nesting success, chick survival, and post-fledging juvenile survival. Retrospective analysis indicated that much of the overall variability in λ and annual productivity was also attributed to annual variation in nesting success. Management of this species has often focused on fall and overwinter survival, but population projection models provided little evidence that survival was the predominant factor affecting population growth of Ruffed Grouse in this region. A suite of confounding factors and demographic processes that drive population trends can differ significantly across a species' range. In the Upper Great Lakes region, management efforts aimed at maximizing reproductive success would likely have the greatest potential influence on Ruffed Grouse population growth. Other types of systematic, regional survey data can also be useful for validating population trends derived from demographic modeling studies.LAY SUMMARYThe Ruffed Grouse (Bonasa umbellus) has been extensively studied, but few efforts have been made to synthesize demographic data into a sensitivity analysis to guide management.A comprehensive understanding of life history traits and vital rates that influence population growth is crucial for maximizing wildlife conservation and management efforts.We summarized Ruffed Grouse vital rates from field studies within the Upper Great Lakes region of Michigan, Minnesota, and Wisconsin, USA, to evaluate population growth.Our analyses projected a stable but highly variable annual rate of population change for Ruffed Grouse in the Upper Great Lakes region.Management efforts aimed at maximizing reproductive success, particularly nesting success and chick survival, would likely have the greatest potential influence on Ruffed Grouse population growth.

Theory suggests that animals should select resources on the basis of perceived fitness benefits, and avoid other available resources that may result in fitness costs. However, resource selection is both a scale- and a life-stage-specific process, in which the importance of different resources may vary among spatial scales of selection and phases of species' life cycles. We investigated multilevel resource selection and summer survival of Ruffed Grouse (Bonasa umbellus) in Maine, USA, to understand life-stage-specific resource selection and the cost of brood rearing. At the landscape level, male Ruffed Grouse selected areas with greater densities of woody stems taller than breast height, while females avoided these areas and selected areas with greater ground coverage by Rubus. Males further selected areas with greater stem densities at the local level, while females again avoided areas with greater stem densities and selected locally available areas with greater ground coverage by Rubus. Weekly s...

The potential for wind energy facilities to affect species of grouse in the grasslands of the Great Plains of North America is a conservation concern. Communication by male Greater Prairie-Chickens (Tympanuchus cupido pinnatus) is essential for lek mating displays and includes low-frequency vocalizations that could be disrupted by wind turbine noise. We studied the effects of wind turbine noise on the boom, cackle, whine, and whoop vocalizations of male Greater Prairie-Chickens recorded at 14 leks located 703 m to 23 km away from a wind energy facility near Ainsworth, Brown County, Nebraska, USA, in 2013 and 2014. First, we assessed ambient sound levels at our study sites. Wind turbine noise contributed to the soundscape; leks

Rapid development of wind energy facilities in the Great Plains of North America has raised concerns regarding their potential negative impact on the nesting ecology of Greater Prairie-Chickens (Tympanuchus cupido pinnatus). We investigated the effects of a pre-existing, 36-turbine wind energy facility on nest site selection and nest survival of Greater Prairie-Chickens in the unfragmented grasslands of the Nebraska Sandhills, USA. In 2013 and 2014, we monitored 91 nests along a 24-km disturbance gradient leading away from the wind energy facility. We found little evidence of an effect of the wind energy facility on Greater Prairie-Chicken nest site selection and nest survival. Instead, we found that the primary drivers of nest site selection and nest survival were related to landscape and habitat factors. Greater Prairie-Chickens avoided nesting near roads, with 74% of Greater Prairie-Chickens selecting nest sites >700 m from roads. Greater Prairie-Chickens selected nest sites with more than twi...

Renewable energy resources have received increased attention because of impacts of fossil fuels on global climate change. In Kansas, USA, optimal sites for wind energy development often overlap with preferred habitats of the Greater Prairie-Chicken (Tympanuchus cupido), a lek-mating prairie grouse of conservation concern. We tested for potential effects of energy development on male Greater Prairie-Chickens in north-central Kansas. We captured males at 23 leks located 0.04 to 28 km from wind turbines during a 2-yr preconstruction period (2007–2008) and a 3-yr postconstruction period (2009–2011). First, we tested for effects of proximity to turbines, habitat, and lek size on annual probability of lek persistence and changes in male numbers. We predicted that energy development might result in behavioral avoidance of areas close to turbines, resulting in increased rates of lek abandonment and fewer males attending surviving leks. We found that distance to turbine had a negative effect on lek persistence for leks ,8 km from turbines during the postconstruction period, supporting the 8-km buffer zone recommended by the U.S. Fish and Wildlife Service as an offset for wind energy projects. Additionally, lek persistence was positively related to number of males counted at a lek and with grassland cover surrounding the lek. Second, we tested for effects of wind energy development on male body mass. We predicted that degraded habitat conditions might result in decreased body mass for males attending leks near turbines during the postconstruction period. Male body mass was ~2% lower during the postconstruction period, but distance to turbine did not affect body mass. Additional study is needed to determine whether short-term effects of turbines on lek persistence influence population viability of Greater Prairie-Chickens.

Males of many species use courtship behavior to attract mates. However, by doing so males may face the associated costs of increased energetic expenditure, reduced foraging time, and elevated predation risk. We investigated the costs of display in lekking male Sharp-tailed Grouse (Tympanuchus phasianellus). We used lek-wide scan sampling to study how males allocated time among courtship display (“dancing”), agonism, foraging, and inactivity in relation to female numbers both within and across days. We also addressed the limited attention hypothesis and estimated visual attentiveness by videotaping 13 males and scoring head turns during these different activities. We found that the proportion of males engaged in display increased significantly with female numbers both within and across days. Additionally, foraging decreased with increasing female numbers both within and across days. Our results also suggested that agonism increased on days of high female attendance after females had left the lek. ...

Leking moths present an evolutionary problem in their apparently simultaneous reversal of male–female attraction. The mating system of Phymatopus (or Hepialus) hecta embraces an unusually wide range of procedures. Both males and females use medium-range olfactory attractants (also probably visual signals), and both sexes will lure, and both will approach, the other, either when flying or perched. This produces an ‘infinite variety’ which includes the classic moth mating procedure (males fly to sessile female); a typical lek procedure (female flies to sessile male); a mating swarm (hovering male follows passing female); and intermediates such as a mutual courtship dance. Male behaviour includes a flying display, two sessile displays, and an escalating war of attrition. The system is versatile, persistent, and probably evolutionarily stable. The lek site has a high density of perches suitable for copulation which facilitate predator-escape by means of a dead drop. The whole supports a model for the evolution of resource-based leks which commence with a concentration of females on a hotspot, leading to a concentration of males; and then an escalating process of sexual selection as males become increasingly attractive over a distance to females, and females use the males as a way of locating the resource. The main stabilizing pressure may be selection for efficient mate acquisition, and as with grouse leking systems, the precondition for evolution was probably having travelling females that actively sought a reproductive resource or a predator free space. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114, 184–201.

Using independently segregating nuclear single nucleotide polymorphisms (SNPs) and mitochondrial control region sequences, we found an east-west division among sampled willow grouse Lagopus lagopus subspecies. This division cut across the range of the subspecies with the largest distribution (lagopus) and thus contradicted existing taxonomic classifications. Russian Lagopus lagopus lagopus tended to cluster with North American willow grouse partly classified as other subspecies. Scandinavian willow grouse (L. l. lagopus) clustered with red grouse from Britain and Ireland (Lagopus lagopus scoticus and Lagopus lagopus hibernicus) but substructuring confirmed the monophyly of the latter. In North America, we could not detect any major genetic divisions apart from two birds described as alexandrae from the Heceta Island (Alaska) when using mitochondrial sequences. Other samples from North America were intermingled regardless of whether they were described as muriei, alexandrae or lagopus .A specimen described as alexandrae was to some extent distinct when analysing the SNP data. The genetic analyses indicated some concordance between genetics and taxonomy but not complete congruence. This is particularly evident for mitochondrial DNA network analyses. We suggest that the taxonomy of this species would benefit by a careful re-examination of the available evidence for subspecies. It appears as if subspecies status is a poor proxy for assigning evolutionary significant units and management units in this species. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110, 77-90. ADDITIONAL KEYWORDS: alexandrae - evolutionary significant unit - hibernicus - kamschatkensis - Lagopus lagopus - muriei - phylogeography - scoticus - willow grouse subspecies.

Directionality is a key feature of vocalizations in birds and can provide insight into vocalizations° function and propagation. Despite recent interest in birds' production of nonvocal acoustic signals, little is known about the directionality of these sounds. Here, we examine the directionality of the drumming display of male Ruffed Grouse (Bonasa umbellus), a nonvocal acoustic signal used in mate attraction and territorial defense. We recorded drumming males with a low-frequency microphone and measured sound-pressure levels with a sound-level meter from three orientations: front (0°), behind (180°), and side (90°). The sound-pressure level was significantly higher in front of and behind a drumming male than on the sides, indicating that the drumming sound radiates primarily along the displaying bird's longitudinal axis. Spectral analyses of the recordings did not, however, yield consistent differences in frequency among the three orientations. The acoustic radiation pattern of the drumming dis...

While sex allocation has been investigated productively at both population and family levels, as yet no general theory has been developed that is capable of linking processes at these two ecological scales, and very few empirical studies have examined cross-scale patterns. In Finnish northern goshawks (Accipiter gentilis), nestling sex ratio of local subpopulations is related to the spatial and temporal variation in the abundance of their principal avian prey, woodland grouse. Using data from an urban breeding population in Hamburg, Germany, I investigated: (1) whether brood sex ratio of goshawks varies with diet composition at the family level; (2) whether such variation could reflect adaptive adjustment; and (3) how family-level allocation can drive population-level patterns, such as those observed in Finland. Feral pigeons (Columba livia) were the most important prey species, with a pooled contribution to total diet of 36%. Brood sex ratio varied significantly with the proportion of pigeons in the breeding-season diet of pairs (increasing male bias). However, there was no evidence for sex-differential effects of diet composition, so it remains unclear whether the observed sex-ratio variation was an adaptive response. As all study pairs inhabited an (urban) environment where pigeons were unusually abundant, family-level sex-ratio adjustment caused a marked male bias in offspring sex ratio at the population level (male-biased nestling sex ratio in four of five years; pooled data: 60% males). This suggests that the large-scale variation observed in Finnish goshawk populations mirrors sex-ratio adjustment shown by individual families in response to small-scale environmental conditions. Apart from linking patterns empirically across ecological scales, this study is, to my knowledge, the first to demonstrate that family-level brood sex ratio varies with realized resource use (diet composition) in a raptor species. Previous studies either failed to find significant associations or, more commonly, violated theoretical assumptions by measuring environmental prey abundance (often integrated over large areas) rather than realized prey use of individual breeding pairs. I conducted a meta-analysis of offspring sex-ratio data from 17 goshawk populations across Europe to put my results into perspective. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 937‐951.

In lek mating systems, females visit aggregations of displaying males and appear to have unrestricted opportunity to choose and mate with any male. Behavioral observations of lekking birds indicate that females generally mate once and that only a small percentage of males gain a majority of copulations. However, genetic analyses of paternity have revealed that multiple males sometimes sire young within one brood. We analyzed paternity of 25 broods of Greater Prairie-Chickens (Tympanuchus cupido pinnatus) breeding in an isolated population in central Wisconsin. We found multiple paternity in 44% of broods (1–4 sires brood-1) and a positive relationship between the number of sires and female home-range size prior to nesting. Multiple paternity was apparently not influenced by local breeding experience: native Wisconsin and translocated females from Minnesota did not differ in the likelihood of multiple mating. The high incidence of multiple paternity may reduce the variance in male reproductive su...

It is often assumed (explicitly or implicitly) that animals select habitat features to maximize fitness. However, there is often a mismatch between preferred habitats and indices of individual and population measures of performance. We examined the influence of fine-scale habitat selection on the overall population performance of the White-tailed Ptarmigan (Lagopus leucura), an alpine specialist, in two subdivided populations whose habitat patches are configured differently. The central region of Vancouver Island, Canada, has more continuous and larger habitat patches than the southern region. In 2003 and 2004, using paired logistic regression between used (n = 176) and available (n = 324) sites, we identified food availability, distance to standing water, and predator cover as preferred habitat components . We then quantified variation in population performance in the two regions in terms of sex ratio, age structure (n = 182 adults and yearlings), and reproductive success (n = 98 females) on th...

We examined the population genetics and phylogenetics of Falcipennis canadensis isleibi, a subspecies of Spruce Grouse from the Alexander Archipelago of southeast Alaska, which was recently given subspecies status on the basis of subtle differences in plumage coloration and its limited distribution on several islands. The taxonomic status of F c. isleibi is particularly consequential, both because little is known about its evolutionary, demographic, and conservation status and because island endemics often face high extinction risks. Samples were collected from central Alaska, British Columbia, and Prince of Wales (POW) and Zarembo (ZAM) islands in the Alexander Archipelago and identified to subspecies using established morphological traits. We sequenced the cytochrome-c oxidase I (COI) subunit of the mitochondrial genome (n = 62) and genotyped each individual at six nuclear microsatellite loci (n = 65). Individuals from POW and ZAM shared a unique mitochondrial haplotype not observed in other p...

Anthropogenic changes in landscapes can favor generalist species adapted to human settlement, such as the Common Raven (Corvus corax), by providing new resources. Increased densities of predators can then negatively affect prey, especially rare or sensitive species. Jackson Hole and the upper Green River valley in western Wyoming are experiencing accelerated rates of human development due to tourism and natural gas development, respectively. Increased raven populations in these areas may negatively influence the Greater Sage-Grouse (Centrocercus urophasianus), a sensitive sagebrush specialist. We investigated landscape-level patterns in raven behavior and distribution and the correlation of the raven data with the grouse's reproductive success in western Wyoming. In our study areas towns provide ravens with supplemental food, water, and nest sites, leading to locally increased density but with apparently limited (

Theory suggests habitats should be chosen according to their relative evolutionary benefits and costs. It has been hypothesized that aspen (Populus spp.) forests provide optimal habitat for Ruffed Grouse (Bonasa umbellus). We used the low phase of a grouse population's cycle to assess the prediction that grouse should occupy aspen and avoid other forest types at low population density because of the presumptive fitness benefits of aspen. On the basis of our observations, we predict how the Ruffed Grouse population will increase in different forest types during the next cycle. In conifer (Pinus spp., Abies balsamea, Picea spp.)-dominated and mixed aspen—conifer landscapes, grouse densities were highest where forest types were evenly distributed. Within these landscapes, male Ruffed Grouse selected young aspen stands that were large and round or square. Although Ruffed Grouse selected young aspen stands strongly, contrary to prediction, they also used other forest types even when young aspen stand...

Birds in which only one sex incubates the eggs are often faced with a direct conflict between foraging to meet metabolic needs and incubation. Knowledge of environmental and ecological factors that shape life-history strategies of incubation is limited. We used continuous videography to make precise measurements of female Greater Sage-Grouse (Centrocercus urophasianus) incubation constancy (percentage of time spent at the nest in a 24-hour period) and recess duration. We used an information-theoretic approach to evaluate incubation patterns in relation to grouse age, timing of incubation, raven abundance, microhabitat, weather, and food availability. Overall, sage-grouse females showed an incubation constancy of 96% and a distinctive bimodal distribution of brief incubation recesses that peaked at sunset and 30 min prior to sunrise. Grouse typically returned to their nests during low light conditions. Incubation constancy of yearlings was lower than that of adults, particularly in the later stage...

Prairie grouse (genus: Tympanuchus) once existed throughout much of North America but have recently experienced significant population declines, isolation, and extinction. In previous molecular studies, contrasting patterns or an unresolved polytomy among Tympanuchus taxa (Tympanuchus phasianellus, Tympanuchus pallidicinctus, and Tympanuchus cupido) have resulted from traditional phylogenetic methods. As an alternative approach, the timing of expansion and the demographic processes that may have lead to this association among haplotypes, namely incomplete lineage sorting or migration, were explicitly investigated by comparing pairwise mitochondrial DNA control region nucleotide differences and through the use of a isolation with migration coalescent model. The timing of geographic expansion and population divergence time estimates generated under these models support previous inferences that Tympanuchus experienced a rapid expansion and diversification in the late Pleistocene 10,000-80,000 years before present. Further, morphological and behavioral differences originally used to describe Tympanuchus species were substantiated with little or no migration identified since population divergence. However, estimates of population divergence and migration between a number of morphologically similar subspecific taxa, including the greater prairie chicken (Tympanuchus Cupido pinnatus), the endangered Attwater's prairie chicken (Tympanuchus Cupido attwateri), and the extinct heath hen (Tympanuchus Cupido cupido), suggest these taxa are as differentiated with each other as they are from other Tympanuchus species. This information will prove useful in conservation efforts by providing estimates of demographic history that have helped shape the evolutionary relationships among Tympanuchus grouse.

The expression of sexual ornaments has been suggested to reliably indicate individual quality, such as the ability to cope with parasites and diseases. The Immunocompetence Handicap Hypothesis (IHH) states that testosterone-dependent ornaments honestly signal such quality because of physiological costs associated with testosterone, such as impaired immune function. We tested predictions of the IHH both correlatively and experimentally in red grouse Lagopus lagopus scoticus. Male grouse exhibit supra-orbital red combs whose size is testosterone-dependent. We found that comb size was not correlated to infection intensity by two parasites (coccidia and the nematode Trichostrongylus tenuis), but it was significantly positively correlated with condition and T-cell-mediated immunity (the ability to mount a primary inflammatory response). We manipulated testosterone by means of implants and re-caught males after a month to investigate the effects on comb size, condition, immunity, and parasite load. Males implanted with testosterone had increased comb size, lost more condition, and had lower T-cell-mediated immunity than control males. Increased testosterone also resulted in a significant increase in coccidia infection intensity but had no effect on T. tenuis burden. The results are consistent with predictions of the IHH and suggest that comb size honestly indicates immunocompetence and males’ ability to cope with certain parasites. Females could thus benefit from choosing mates based on the expression of this sexual trait. Key words: Immunocompetence Handicap Hypothesis, parasite, red grouse, sexual ornament, T-cell-mediated immunity, testosterone. [Behav Ecol 15:930–937 (2004)]

Blackgrouse (Tetrao tetrix) in the high eastern region of Belgium form a very small population that is close to extinction. Biologists have followed them closely for many years. The numbers of cocks on their mating grounds are counted each spring, with data available for 30 years. In modelling this population, we are interested to see whether we can obtain an adequate model for the available data by using only climatic information. If a population is in an ecologically viable equilibrium, it should be able to adjust to a changing habitat; short-term variations in weather should be the only major influence on the size of the population. This can have an immediate effect on the survival of the young, but also a more delayed effect through the numbers of grouse reaching maturation. To account for the latter, population levels in the previous 2 years are included in the model because the cocks take 2 years to reach maturity. We know that habitat factors, especially variations in the number of foxes as influenced by changes in methods of rabies control, the activity of poachers and evolution of the plant habitat in the region over the observation period, have an effect. However, the question is not whether such variables are missing; we know that they are. The question concerns the adequacy and appropriateness of a climatic model for describing the observed variations. For a further discussion of these assumptions, and details on the models and the conclusions, see

Several aspects of the ecology and biology of red grouse ( Lagopus lagopus scoticus ) could prevent the complete admixture of genes within and between populations. Male red grouse display a high degree of natal philopatry, are territorial, and show less aggression to kin than to non-kin. Such factors acting in combination predict limited male-mediated gene flow, which will promote social structure within a population by the formation of stable kin clusters, and facilitate a rapid rise in allelic coancestry and/or inbreeding. In this study we utilize hypervariable microsatellite polymorphisms to examine the extent of social affiliation between relatives in a moorland population of grouse from NE Scotland. Levels of genetic relatedness between individual male red grouse occupying territories at Glas Choille in the spring and autumn of 1995 were examined, and kin clusters delimited. Nine kin groups (mean size =2.4 individuals) were identified prior to breeding in the spring, which increased to 11 kin groups (mean size =4.0 individuals) when territories were reformed in the autumn. The majority of those individuals that were recruited into the adult population during the autumn already had a first-order male relative established, supporting the hypothesis that recruitment is facilitated by behavioural interactions among relatives. The demographic and population genetic consequences of philopatric recruitment and kin clustering are examined and discussed.

I review diet selection in grouse and waterfowl in the context of their herbivorous diets and discuss adaptations to herbivory in these groups. Both grouse and waterfowl prefer plant foods containing higher concentrations of protein than nonpreferred foods; grouse and small waterfowl include invertebrates in the diet to meet protein demands during periods of high tissue production. Grouse tend to avoid plant foods containing high concentrations of anti-herbivore compounds and the relative roles of these compounds versus nutrients in diet selection by grouse is presently unclear. Grouse and waterfowl have similar digestive morphology, except for the ceca, which are 5 times longer in grouse than in geese. Enlarged ceca are associated with improved nitrogen economy in grouse; evolution of these structures in geese may have been precluded by energetic costs of carrying enlarged ceca during migration.

Many North American Tetraoninae exhibit migratory behavior (Hoffman and Braun 1975, Herzog and Keppie 1980, Cade and Hoffman 1993, Schroeder and Braun 1993), either as partial (only some individuals migrate) or differential (age or sex classes differ in timing and/ or distance) migrants between seasonal habitats (Terrill and Able 1988). Tetraoninae may migrate because of elevational or seasonal differences in habitat availability and selection, or fidelity to seasonal-use areas (Herzog and Keppie 1980, Schroeder and Braun 1993), and these migrations are typically 16 km were uncommon), allowing most individuals to find required habitats within a relatively small annual range. In contrast, the ecology of migratory populations is more complex because individuals must cope with long-distance movements to suitable seasonal ranges (Dalke et al. 1963, Berry and Eng 1985, Connelly et al. 1988, Wakkinen 1990). Although Sage Grouse do not undertake migrations at a scale similar to some avian species such as Anseriformes (Bellrose 1980), Neotropical migratory Passeriformes (Finch and Stangel 1993), or Charadriiformes (Krementz et al. 1994), their movements still m et most ecological definitions of migration (e.g., Sinclair 1983). Connelly et al. (1988), Wakkinen (1990), and Roberts n (1991) investigated the ecology of a migratory Sage Grouse population inhabiting a xeric environment (< 25 cm annual precipitation) in southeastern Idaho. Grouse used contiguous areas for wintering, breeding, and nesting but moved as far as 82 km to summer range at either higher or lower elevations. Grouse return to winter range beginning in late fall (Robertson 1991). Movements to summer range presumably occur because Sage Grouse breeding and nesti g ranges lack mesic habitats, such as wet meadows and iparian areas, that provide succulent vegetal foods for birds throughout summer (Autenrieth 1981, Connelly et al. 1988). Although reports of distance moved from breeding to summer ranges are common, little information regarding relationships between timing of thes movements and vegetal characteristics or environmental factors are available. Nest fate also may influence the ability of females to initiate migration to summer range because successful females may delay migration (Schroeder and Braun 1993). Migratory birds may rely on exogenous (environmental) factors (Terrill 1990), endogenous circannual rhythms (Berthold 1990, Gwinner 1990), or a combination of both (Krementz et al. 1994) for migrational timing cues. Sage Grouse appear to initiate migration to summer range at different times within and among years (Connelly et al. 1988), suggesting the cue for migrational timing may be influenced by exogenous factors. However, no empirical data exist to document timing and progression of plant desiccation, how weather variables might influence desiccation, or how migrational timing may be influenced by plant moisture content. We hypothesized that (1) cumulative annual precipitation and temperature influence timing of spring and summer vegetal desiccation, (2) vegetal moisture content would be higher in plants collected at sites used by Sage Grouse than at random sites, and (3) annual timing of Sage Grouse migration is related to vegetal moisture content and nest fate. 1 Received 15 February 1996. Accepted 24 July 1996. 2 Present address: U.S. Army Corps of Engineers, Waterways Experiment Station, Environmental Laboratory, 3909 Halls Ferry Rd., Vicksburg, MS 39180, e-mail: fischer@ex 1 .wes.army.mil

The delineation of species groups and determination of relationships among taxa within the Tetraoninae (grouse and ptarmigan) have relied heavily on anatomical and behavioral specializations associated with reproduction. As a result, the various classifications of tetraonines differ considerably with respect to the phylogenetic relationships depicted for the primary species groups. We used nucleotide sequence data derived from the mitochondrial cytochrome-b gene to examine relationships among all New World taxa and the major Old World "superspecies" groups of grouse and ptarmigan. The cytochrome-b sequence data: (1) indicated an early divergence of the Bonasa species; (2) grouped Dendragapus obscurus with Tympanuchus and supported an association of these taxa with Lagopus and Tetrao; and (3) suggested that tetraonines underwent a period of rapid diversification in North America. The molecular phylogeny provides support for adaptive interpretations of morphological and behavioral variation among grouse and ptarmigan and indicates that the complex reproductive systems of tetraonines reflect homoplasy probably as a result of convergent evolution. We recommend that grouse and ptarmigan taxonomy incorporate genetic considerations and that classifications reflect common ancestry. Received 9 October 1995, accepted 5

ABsmAcT.-Trailing-edge notches, formed by shortened first secondaries, characterize the wings of most galliforms. I investigated the function of these notches with comparative measurements of notch size taken from extended-wing specimens and with experimental studies of model wings of four representative species. Pheasants, quail, and turkeys, all of which use flight to escape predators, have wide wings and deep notches. Grouse with dark flight muscles have long, narrow wings with small trailing-edge notches and typically fly relatively long distances from one foraging site to another. Grouse with light colored flight muscles have short, broad wings with large trailing-edge notches and mostly fly from ground to canopy or from branch to branch to reach their food. Model wings of two pairs of galliforms with different wing shapes were used in the experiments. White-tailed Ptarmigan (Lagopus leucurus) and Sage Grouse (Centrocercus urophasianus) have small notches, high aspect ratios, relatively heavy wing loadings, low maximum lift coefficients, and dark pectoral muscles. In contrast, Wild Turkey (Meleagris gallopavo) and California Quail (Callipepla californica) have deep notches, low aspect ratios, relatively light wing loadings, high lift coefficients, and light colored pectoral muscles. Experiments using model wings in a water flow tunnel show that the trailing-edge notch increases the maximum lift-to-drag ratio and stabilizes airflow around the wing, but reduces the maximum lift coefficient. Thus, the trailing-edge notch increases performance in vertical and slow flight but reduces efficiency in level flight. Such a function is consistent with the suite of differences these birds show in muscle color, wing shape, and predominant mode of flight. Received 17 November 1995, accepted 27 February 1996.

We investigated variations in egg production of captive hen Red Grouse Lagopus lagopus scoticus in relation to food intake, weight change, and parasitism by the nematode Trichostrongylus tenuis. Experimental infections of T. tenuis were used to mimic the relative effects on laying grouse of an adult worm burden, the resumed development of over-wintered worm larvae or no infection. Variations in egg production were significantly related to hen food intake and weight loss during laying but not to food intake or weight gained in the five weeks before laying. This supports the Thomas (1988) hypothesis that grouse produce eggs from 'income' rather than 'capital' reserves. There were no significant differences in the total weight, number or rate of eggs produced by hens from different treatment groups. However, hens infected with worms developing at the onset of laying lost significantly more weight while laying and, at the end of egg laying, were 13% lighter than other birds. In wild birds this could affect the quality of incubation and maternal care of chicks. The precise timing of the resumed synchronous development of previously arrested T. tenuis larvae may be a critical determinant of how this parasite affects egg production by wild Red Grouse.

SAYCE, J. R., AND G. L. HuNT, JR. 1987. Sex ratios of prefledging Western Gulls. Auk 104:33-37. SHKLAREVITCH, F. N., AND V. F. NIKULIN. 1979. Sex determination of day-old ducklings in the field and sex ratios of broods in the Common Eider. Pages 106-112 in The ecology and morphology of eider ducks in the USSR (A. A. Kischinski, Ed.). Publ. House Nauka, Moscow [in Russian]. SNEDECOR, G. W., AND W. G. COCHRAN. 1980. Statistical methods, 7th ed. Iowa State Univ. Press, Ames. SOKAL, R. R., AND F. J. ROHLF. 1995. Biometry: The principles and practice of statistics in biological research, 3rd ed. W. H. Freeman and Co., New York. SowLs, L. K. 1955. Prairie ducks: A study of their behavior, ecology and management. Stackpole Books, Harrisburg, Pennsylvania. SWENNEN, C., P. DuIvEN, AND L. A. REYRINK. 1979. Notes on the sex ratio in the Common Eider, Somateria mollissima (L). Ardea 67:54-61. TRIVEs, R. L., AND D. E. WILLARD. 1973. Natural selection of parental ability to vary the sex ratio of offspring. Science 179:90-92. WEATHERHEAD, P. J. 1983. Secondary sex ratio adjustment in the Red-winged Blackbird (Agelaius phoeniceus). Behav. Ecol. Sociobiol. 12:57-61. WEATHERHAD, P. J. 1985. Sex ratios of Red-winged Blackbirds by egg size and laying sequence. Auk 102:298-304. WELLER, M. W. 1965. Chronology of pair formation in some Nearctic Aythya (Anatidae). Auk 82:227235. ZWIcKEL, F. C., AND J. F. BENDELL. 1967. Early mortality and the regulation of numbers in Blue Grouse. Can. J. Zool. 45:817-851.

Systematic relationships among North American grouse and ptarmigans (Tetraoninae) are not well defined because traditional classifications were based on morphological and behavioral characters with limited taxonomic utility. Restriction enzyme analysis of mitochondrial DNA (mtDNA) was used to generate a phylogeny for North American tetraonines that was then utilized to test previous phylogenetic hypotheses for the group and to examine the origin and evolution of complex reproductive behaviors and morphological features characteristic of grouse and ptarmigan species. Nucleotide sequence divergence among congeneric species derived from mtDNA restriction fragment patterns varied extensively, ranging from 0.28% in prairie grouse (Tympanuchus) to 4.06% among ptarmigans (Lagopus) and 10.15% between Blue Grouse (Dendragapus obscurus) and Spruce Grouse (D. canadensis). Using the Northern Bobwhite (Colinus virginianus) as an outgroup, the molecular phylogeny partitioned species into three primary groups: (1) Tympanuchus; (2) Lagopus, Dendragapus obscurus, and Tetrao urogallus (the European Capercaillie); and (3) the Ruffed Grouse (Bonasa umbellus), Dendragapus canadensis, and Sage Grouse (Centrocercus urophasianus). Prairie grouse were genetically distinct from other grouse species, but a polyphyletic distribution of haplotypes and limited mtDNA differentiation within Tympanachus suggest that divergence among the prairie grouse occurred very recently. Within Lagopus, the Willow (L. lagopus) and Rock (L. mutus) Ptarmigans were more closely related to each other than either was to the White-tailed Ptarmigan (L. leucurus). Dendragapus canadensis grouped with Bonasa umbellus; whereas D. obscurus was allied with Lagopus and Tetrao. Thus, the genus Dendragapus as currently constructed is polyphyletic (i.e., D. canadensis and D. obscurus have had separate evolutionary histories) and the morphological similarities between the two species may be attributable to convergent adaptation to coniferous forest. We inferred from the molecular phylogeny that the complex reproductive systems in tetraonines have arisen independently and that corresponding morphological and behavioral specializations may reflect parallel evolutionary trends

Interspecific hybridization has been reported in at least 52 of 516 nonmarine bird species in North America (Johnsgard 1970, Mayr and Short 1970, Short 1965, 1972). It tends to occur infrequently, however, except where allopatric species are brought into contact by range expansions (Cade 1983). Groups in which interspecific hybridization is particularly common include warblers, grouse, and hummingbirds (Mayr and Short 1970, Oliphant 1991). Instances of interspecific hybridization in birds of prey are uncommon except in captivity (Newton 1979, Cade 1983, Oliphant 1991). In owls, interspecific hybridization appears to be rare. Johnsgard (1988) reported instances of hybridization between Eastern Screech-Owls (Otus asio) and Western Screech-Owls (0. kennicottii) in Texas, and Voous (1989) reported instances of hybridization between Whiskered Screech-Owls (0. trichopsis) and Western Screech-Owls in Arizona. Evidence of hybridization in the genus Strix has been limited to Ural Owls (S. uralensis) hybridizing with Tawny Owls (S. aluco) in captivity (Mikkola 1983). We present the first records of hybridization between the Northern Spotted Owl (S. occidentalis caurina) and Northern Barred Owl (S. varia varia), two species that are thought to be closely related and that have recently become sympatric (Grant 1966, Taylor and Forsman 1976, Hamer 1988). Since at least the early 1950s, the Barred Owl has been expanding its range into western North America. In the process, it has invaded much of the historical range of the Spotted Owl (Grant 1966, Taylor and Forsman 1976, Hamer 1988). Barred Owls are now common in forested areas in southwestern British Columbia and northern Washington (Hamer 1988, Dunbar et al. 1991), and they are rapidly increasing in Oregon and northern California. Increasing sympatry between Barred and Spotted owls has led to speculation that the Northern Spotted Owl, which is listed as a threatened species (U.S. Fish and Wildlife Service 1990), may be further threatened by competition with the Barred Owl, as well as by habitat loss (Taylor and Forsman 1976, Dunbar et al. 1991). The possibility that sympatry might also result in hybridization between the two species has not been previously considered. Records of hybrids.-Three adult Spotted Owl/Barred Owl hybrids, two in Washington and one in Oregon, were confirmed during 1989-1992, and one juvenile hybrid was produced by a female Barred Owl paired to a yearling male Spotted Owl in Oregon in 1992. All hybrids were identified by their unique plumage characteristics, vocalizations, and measurements. The first hybrid was an adult male seen on 23 March 1989 at Baker Lake in the Washington Cascades Range, 30 km south of the United States/Canadian border. This bird was fitted with a radio transmitter in 1989 and recorded in the same area in spring 1990, 1991, and 1992. Its nesting status was not determined, but it was always seen with a female Barred Owl. Both birds aggressively defended the territory in response to playback calls. The second hybrid, an adult male located in the Klamath Mountains 29 km northeast of Medford, Oregon, in 1990 was paired with a female Barred Owl. This pair produced two young in 1990 and three young in 1991. In 1992 the Medford hybrid was displaced by a male Barred Owl. It was relocated in June 1992, 1 km from its previous nesting site and did not appear to be paired (James Harper pers. comm.). Another suspected hybrid (or possibly the same individual) was seen and heard in this area in 1987 (James Harper pers. comm.). The third hybrid was an adult female observed several times in May 1991, 2 km south of Ozette Lake, Washington, near the northwestern tip of the Olympic Peninsula. When this bird was captured, we found that it had been banded as a juvenile in 1986, 277 km to the southeast in the Cascade Range of southern Washington. The original bander suspected that the bird may have been a hybrid, but was unsure because it was not fully feathered and because both parents were not observed (H. Allen pers. comm.). When located in 1991, the Ozette Lake female was paired with an adult male Spotted Owl. No young were observed, but the female had a brood patch that was regressing, which suggested that nesting may have been attempted. Both birds were observed together in 1992 when nesting was again attempted but failed for unknown reasons. In addition to the three adult hybrids described above, a fourth hybrid from a pairing between a Barred Owl and Spotted Owl was confirmed in 1992 in Douglas County, Oregon, 8 km southeast of Canyonville. This pair consisted of a yearling male Spotted Owl and an adult female Barred Owl. They produced one young, which was first observed on 1 June 1992. The F, hybrid juvenile was fitted with a tail-mounted radio

A study was carried out in native pinewoods at Abernethy and Glen Tanar to investigate the effect of forest fences on capercaillie and black grouse. Collisions occurred at a rate of 0.25 and 0.03 per km of fence per month for capercaillie and black grouse respectively. Male capercaillie had a higher proportion of severe and fatal collisions than females. Capercaillie tended to collide with those sections of fence where there were moderately sized pines (8.5 m) close (within 4.4 m) to the fence. Collision sites close to trees were most strongly associated with the height of exposed trunk, suggesting that capercaillie fly under the canopy and fail to see the fence. The annual mortality rate of radio-tagged capercaillie caused by collisions was 32 per cent indicating that this was a major mortality factor. Collisions were most frequent between September and November when capercaillie were dispersing. It is recommended that fences are removed where and when they are unnecessary, or are made more visible, or are set back from old woodland.

Ruffed Grouse (Bonasa umbellus) consumption of quaking aspen (Populus tremuloides) flower buds is determined, in part, by the concentration of coniferyl benzoate (CB) in the bud. Understanding the physiological effects of this compound may clarify whether the association between annual fluctuations in CB and Ruffed Grouse population levels has a cause/effect relationship. We determined the maximum level of dietary CB that Ruffed Grouse can tolerate by feeding captive grouse a formulated diet treated with eight concentrations of CB. Loss of body mass was used to indicate toxicity. Biotransformation products from CB were identified in order to determine the detoxication mechanisms em- ployed and the presence of potentially toxic CB metabolites. Ruffed Grouse will consume up to 2 g kgg' day-' of CB before rapid mass loss ensues. High dietary levels of CB were associated with decreased food intake and increased water excretion. Serum uric acid, as- partate aminotransferase, and alanine aminotransferase levels did not change significantly with increased levels of dietary CB. Mass loss that was associated with a CB intake of 2.3 g kg-' day-' could be explained by decreased food intake but could not be attributed to any specific toxic effect. It is uncertain whether the decreased food consumption that occurred at high CB intake levels was prompted by toxicity avoidance or decreased food palatability. Ruffed Grouse appear to use glucuronic acid, sulfate, and omithine conjugation, along with hydrolysis, reduction, and oxygenation reactions, when detoxifying CB. Nine biotransfor- mation products were identified, including ferulic acid and 4-vinylguaiacol. The latter com- pounds are known to interfere with reproduction in other animals.

Captive Red Knots (Calidris canutus) fed soft food pellets developed atrophied stomachs, and were reluctant to eat their usual hard-shelled mollusc prey. An interspecific comparison among shorebirds showed that wild Red Knots and other intact-mollusc-eating species have gizzards with relatively great mass but very small proventriculi. Within six different shorebird species, the heavier individuals usually had the heavier stomachs as well, but in Red Knots and Bar-tailed Godwits (Limosa lapponica) we identified heavy premigrant individuals with reduced stomach masses, suggesting a reallocation of protein reserves before long-distance flights. In both species reduced stomach mass was associated with a relatively soft diet. We were unable to show that during adjustment of stomachs to hard-shelled prey, such prey are broken down to smaller fragments. We attribute this to the counteractive influence of the pylorus during adjustment. We summarize the suggested stomach/diet interactions as a network of causal relationships and feedback loops involving the type of diet and gizzard mass. We identify two basic modifiers of gizzard mass: one working via endurance training and disuse atrophy; and another involving endocrine and/or neural mechanisms. It is likely that, in the course of their annual cycle, shorebirds are prevented from achieving maximal digestive performance owing to seasonal changes in feeding habitats and diet enforced by their long-distance migrations.

Experiments that remove individuals are very useful in addressing questions in population and behavioral ecology (Hannon 1986). If experimental designs require the absence of individuals for relatively short durations there are a number of ecological and ethical reasons to hold the removed animals in captivity. For example, populations that exist at low density or have low fecundity may have difficulty recovering from removal experiments, particularly when older, experienced or high quality individuals are removed. Altering the demographic structure of a population may have behavioral or other consequences that could reduce the reliability of results from studies in future years. Releasing removed individuals elsewhere may be undesirable as they may return to the study site during the experiment, or they may survive and reproduce poorly at the new site due to lack of familiarity with the area, or reduced competitive abilities with individuals residing in the new area. Although it may be desirable to maintain removed animals in captivity, wild birds often survive poorly or suffer loss of body condition in captivity, especially some species of Tetraoninae such as grouse and ptarmigan (West 1968, West and Meng 1968, McEwen et al. 1969, Moss 1972, Pendergast and Boag 1971). This study was part of a larger investigation that used removal experiments to examine the importance of biparental care in Willow Ptarmigan (Lagopus lagopus) for survival and body condition of offspring and breeding females (Martin and Cooke 1987, Martin 1989). In this paper, we report methodologies that improved survival in captivity of Willow Ptarmigan removed during the breeding season. Also, we measured survival in subsequent years of birds placed in captivity. METHODS AND STUDY AREA

REDFIELD, J. A. 1974. Genetics and selection at the Ng locus in Blue Grouse (Dendragapus obscurus). Heredity 36: 69-78. RICE, W. R. 1989. Analyzing tables of statistical tests. Evolution 43: 223-226. SOKAL, R. R., & F. J. ROHLF. 1981. Biometry. New York, W. H. Freeman and Co. SZYMURA, J. M., & N. H. BARTON. 1986. Genetic analysis of a hybrid zone between the fire-bellied toads, Bombina bombina and B. variegata, near Cracow in southern Poland. Evolution 40: 1141-1159. WAPLES, R. S. 1989. Temporal variation in allele frequencies: testing the right hypothesis. Evolution 43: 1236-1251. WRIGHT, S. 1978. Evolution and the genetics of natural populations: IV. Variability within and among natural populations. Chicago, Univ. Chicago Press. ZINK, R. M. 1983. Evolutionary and systematic significance of temporal variation in the Fox Sparrow. Syst. Zool. 32: 223-238. 1986. Patterns and evolutionary significance of geographic variation in the Schistacea group of the Fox Sparrow (Passerella iliaca). Ornithol. Monogr. 40. , M. F. SMITH, & J. L. PATTON. 1985. Associations between heterozygosity and morphological variance. J. Heredity 76: 415-420. , & D. J. WATT. 1987. Allozymic correlates of dominance rank in sparrows. Auk 104: 1-10. , & D. W. WINKLER. 1983. Genetic and morphologic similarity of two California Gull populations with different life history traits. Biochem. Syst. Ecol. 11: 397-403.

Renesting in Tetraonidae has been investigated in a number of studies (e.g., Patterson 1952, Zwickel and Lance 1965, Giesen and Braun 1979, Parker 1981, Bergerud 1988, Bergerud and Gratson 1988). Unfortunately, information on renesting by Sage Grouse (Centrocercus urophasianus) is limited and highly variable. Both Patterson (1952:105) and Eng (1963) reported that renesting by Sage Grouse is relatively rare (

Nest-site selection in birds is a function of various factors, e.g., philopatry, microclimate, degree of concealment from predators, and density and characteristics of vegetation (Welty and Baptista 1988, Gill 1990). Recently, Erckmann et al. (1990) tested experimentally whether old nests were used by Red-winged Blackbirds (Agelaius phoeniceus) as cues to assess the quality of habitat for placement of nest-sites ("old-nest" hypothesis). They concluded that old nests were of little or no importance as cues in nest-site selection, based on their findings that nest densities did not necessarily increase in plots containing old nests compared to plots without old nests. Moreover, Erckmann et al. (1990) recommended that the old-nest hypothesis be examined in other avian species. Management of small (1 ha), even-aged plots for Ruffed Grouse (Bonasa umbellus) habitat via forest clear-cutting creates suitable habitat for an assemblage of breeding-bird species that are adapted to nesting in brushy vegetation or along edges (Yahner 1987, 1991). Several of these species, such as Gray Catbirds (Dumetella carolinensis) and Field Sparrows (Spizella pusilla), arrive on breeding grounds prior to complete leaf-out of vegetation. Furthermore, above-ground nests established during the previous breeding season in evenaged plots can remain intact on nesting substrate into the subsequent breeding season (R. H. Yahner, pers. observ.). Thus, old bird nests may serve as indirect cues of habitat suitability to these birds when establishing nest-sites (after Cody 1985). If this were the case, then I would predict that birds arriving in spring would preferentially select even-aged plots with higher densities of old nests than those with lower densities. In this study, I tested whether numbers of nests established by birds of all species combined in even-aged plots were affected by removing or increasing the numbers of old nests from the previous breeding season. My study was conducted on a 240-ha portion of the Barrens Grouse Habitat Management Area (HMA), State Game Lands 176, Centre County, Pennsylvania (Yahner 1991). The study area was located within the treated sector of the Barrens Grouse HMA, which was managed by the Pennsylvania Game Commission since 1976 using an even-aged system of forest clear-cutting to create habitat for Ruffed Grouse (Yahner 1991). The study area contained 60 contiguous, 4-ha blocks; each block was subdivided into four 1-ha (100x 100-m) plots arranged in a clockwise pattern (termed plots AD). Plot A (western plot) was clear-cut in winter 19761977, plot B (northern plot) in winter 1980-1981, and plot C (eastern plot) in winters 1985-1986 or 19861987; plot D (southern plot) consisted of 60-year-old forest stands. This resulted in a checkerboard pattern of four age classes in each block (Yahner 1991). Received 27 July 1992. Accepted 29 October 1992. SHORT COMMUNICATIONS 239

MCEWEN, L. C., D. B. KNAPP, AND E. A. HILLIARD. 1969. Propagation of prairie grouse in captivity. J. Wildl. Manage. 33:276-283. Moss, R. 1972. Effects of captivity on gut lengths in Red Grouse. J. Wildl. Manage. 36:99-104. MYRBERGET, S., AND S.-J. SKAR. 1976. Fat and calorific content of Willow Grouse in autumn and winter. Norwegian J. Zool. 24:41-45. PENDERGAST, B. A., AND D. A. BOAG. 1971. Maintenance and breeding of Spruce Grouse in captivity. J. Wildl. Manage. 35:177-179. ROBB, L. A., K. MARTIN, AND S. J. HANNON. 1992. Spring body condition, fecundity and survival in female Willow Ptarmigan. J. Anim. Ecol. 61:215223.

Alexander (1975) described a nonresource-based mating system as one where males offer mates and young only gametes. Studies of nonresource-based mating systems are important in understanding mate choice and evolution because complicating variables are not involved. In this system, female choice is theoretically based only on benefits derived from males. Sharp-tailed Grouse (Tympanuchus phasianellus) exhibit a nonresource-based mating system. During the breeding season, males display on leks (Lumsden 1965, Hjorth 1970) with females preferring males with territories located centrally in the lek (Lumsden 1965, Hjorth 1970). We examined why females prefer to mate with central males on the lek. Specifically, do females that choose central males benefit by increased probability of fertilization (Avery 1984)? We relate increased probability of fertilization to sperm availability (Eng 1963) and sperm number (David et al. 1979). Sperm must be available at the appropriate time (i.e., when females are receptive) and in adequate quantity to ensure fertilization of ova. If sperm are inadequate in quantity, females risk reproductive success for the year, as females of lekking grouse species typically copulate only once (Kruijt and Hogan 1967, Wiley 1973).

from Minnesota hunters and showed how frequency of color phases varied in relation to grouse population cycles, providing a basis for other researchers to demonstrate the linkage of color phases and aspects of grouse behavior and reproduction. Hundreds of students, researchers, land managers and private forest owners have been influenced by Gullion and his research. In the Ruffed Grouse Society he played a key role by authoring wildlife-management booklets and newsletter articles, and by serving on the national board of directors and as chairman of the research committee since 1972. Gullion authored over 160 professional and popular articles including Grouse of the North Shore (1984) and The Ruffed Grouse (1989, Minocqua, Wisconsin). During his final year he was honored by the Minnesota Forestry Association with an award for "excellence in wildlife habitat management"; by the North Central Section of the Wildlife Society with its premier award, the Professional Award of Merit; by the Izaak Walton league with its Honor Roll Award; and by Minnesota Governor Arne Carlson for "outstanding work in forestry and Ruffed Grouse research." The Department of Fisheries and Wildlife, University of Minnesota, has established a fund for an endowed chair to honor Gordon Gullion and to perpetuate his work.

In many species, adult birds lay earlier and have higher reproductive success than do yearlings. We found no difference, however, between adult and yearling female Willow Ptarmigan (Lagopus lagopus alexandrae) in date of clutch initiation, clutch size, hatching success, number of fledged young, or territory size. Adult females defended their broods more vigorously, and more were observed with broods, a situation suggesting that more yearlings lost their eggs or young and did not renest. Pairs composed of two adults produced more fledged young than did pairs composed of two yearlings, but clutch size and date of clutch initiation were similar in the two groups. We suggest that the following factors may allow yearlings to reproduce almost as successfully as adults: (1) a reduction in competition with adults for territories because of high population turnover, (2) the presence of extensive male parental care and precocial young, and (3) a dependence on a food source that is readily available and can be obtained without specialized foraging skills. Received 8 August 1983, accepted 28 March 1984. HYPOTHESES concerned with the factors that influence the onset of breeding in birds focus at three different levels: (1) on general environmental cues, such as changes in photoperiod or rainfall, that explain differences in timing among species or among geographical areas (reviewed by Wingfield 1983); (2) on specific extrinsic factors, such as weather or the availability and quality of food, that explain differences in timing among populations or among years (e.g. Perrins 1970, Zwickel 1975, Greenlaw 1978); and (3) on intrinsic factors, such as age and experience of the female or the male, or on genetic factors that explain differences in timing among individuals within populations (e.g. Perrins and Moss 1974, Finney and Cooke 1978, Harvey et al. 1979, van Noordwijk et al. 1980). In this paper we concentrate on intrinsic factors, specifically the influence of age on reproductive performance. Age and experience have long been considered to be important variables in explaining not only the timing of breeding but the reproductive output as well. In many species, older birds lay earlier and have higher reproductive success than first-time breeders (e.g. Nelson 1966, Crawford 1977, Blus and Keahey 1978, Middleton 1979). This has been attributed to ' Present address: Department of Zoology, University of Alberta, Edmonton, Alberta T6G 2E9, Canada. the inexperience of young birds in locating food required for egg formation (Lack 1968) and to social inhibition of young birds when they compete with adults for breeding sites (WynneEdwards 1962). In some species, however, firsttime breeders do just as well as older birds (e.g. Leinonen 1973, Myrberget 1967). In this paper, we compare timing of breeding, reproductive output, and territory size of adult and yearling Willow Ptarmigan (Lagopus lagopus alexandrae) of both sexes. We then compare Willow Ptarmigan with other species of grouse and discuss the effects of mating-system type, population demography, and other factors on the timing of breeding and reproductive output of young birds.

STUDENTS have long been intrigued by the drumming of the Ruffed Grouse (Bonasa umbellus). Physically, drumming is a wingbeating display performed from a stationary position, usually upon an elevated object known as a "drumming log." The drumming performance has been described in detail by Bump eta]. (1947: 274-276) and Hjorth (1970: 220-225). Functionally, drumming is believed to correspond fully to song, which is lacking in the species (Hjorth 1970: 497), to facilitate spacing of males (Alien 1934, Fow]e 1953: 91), stimulate female sexual development (Hjorth 1970: 497), and to attract females (Alien 1934, Brander 1967). Numerous ideas have been advanced about how the noise is produced (cf. Bump eta]. 1947: 276-278). Recent]y, Hjorth (1970: 225-233) has suggested new explanations of the related questions of how the sound is generated and how the grouse is able to maintain its balance during the drumming performance. The number of wingbeats in and the duration of a drum are variable both within and among individuals (Aubin 1972). The drumming sound is audible to the human ear up to distances of % to • mile (Sumanik 1966: 38) or more. Although grouse have been reported to turn their heads in reaction to neighbors' drums (Hjorth 1970: 489), no reports of how far a grouse can perceive drumming are available in the literature. Use of the radiote]emetric method has enabled the remote determination

Movements of yearling male Blue Grouse (Dendragapus obscurus) were monitored by radio telemetry during the springs of 1980 and 1981, on Hardwicke Island, British Columbia. The locations of the birds were clumped around territories of adult males. Most birds were associated with a few occupied territories, others settled near vacant sites that had been used as territories in previous years, and a few moved widely over the breeding range. Some territories attracted more yearlings than others. Presumed costs and benefits that may be associated with different types of spatial patterns of yearling males are discussed.

LITTLE is known of the ecology of the Common Raven (Corvus corax) population that inhabits the narrow belt of mountains from north Georgia to northern Pennsylvania. This disjunct group is a remnant of a previously larger, contiguous population (A.O.U. 1957). To our knowledge, only one account of the food habits of this isolated population has been published. Murray (1949) reported the animal remains found below two cliff nests in Rockbridge County, Virginia. Included were the bones of flying squirrels (Glaucomys volans), gray squirrels (Sciurus carolinensis), a Norway rat (Rattus norvegicus), a Mourning Dove (Zenaida macroura), a Blue Jay (Cyanocitta cristata), a Ruffed Grouse (Bonasa umbellus), a snake, and remains of grasshoppers. Reports from other regions indicate that Common Ravens rely heavily on carrion (Ratcliffe 1962, White and Cade 1971, Dorn 1972). Some students believe the raven has considerable potential as a predator (Craighead and Craighead 1956: 339; White and Cade 1971; Dorn 1972). That ravens frequent garbage dumps is well-known (Bent 1946: 227-262). Our objectives of the research were to determine the food habits of Common Ravens in Virginia during two critical periods of the yearwinter and the nesting season. Of particular interest were (1) the importance of prey as a food source, (2) possible economic implications of their food habits, and (3) the importance of garbage dumps as a food source. The study was made possible by the discovery of a nocturnal winter raven roost and the relocation of the apparent nonbreeding segment of the roost following the dispersal of the winter roost at the beginning of the nesting season. A concurrent study of nesting habitat made possible a search of 20 active nest sites for castings. The research was conducted in the Ridge and Valley Physiographic Province of Virginia, a region of parallel ridges that rise 1000 to 2000 feet above the intervening valleys. The ridges are covered by oak forests (Braun 1967) while the valleys are interspersed forest and pastures. The numerous cliffs and remote woodlands have provided a refuge for the species at a time when its numbers were being reduced throughout the eastern United States.

MOSS, R., 1989. Management of heather for game and livestock. Heather provides food and cover for moorland herbivores. Interactions between soils, drainage, climate, muirburn and grazing affect the species composition, structure and growth of moorland swards. Together, these aspects of a sward determine which and how many herbivores it can support. Grazing and burning maintain much heather ground which would otherwise revert to scrub or woodland. Heavy grazing by ungulates can turn a heathery sward into a graminaceous one, so reducing numbers of grouse and mountain hares. On good soils, invading graminoids are usually nutritious grasses and the carrying capacity for ungulates can increase. On poor soils, grazing and frequent burning may lead to swards dominated by poor quality grasses and sedges so that the carrying capacity for ungulates declines. One way of reinstating heather dominance is to remove livestock; where there are no heather plants left, other techniques may be necessary.

We examined extrinsic and intrinsic factors that might influence the timing of clutch initiation and determined the relationship between timing and reproductive success in two populations of Willow Ptarmigan (Lagopus lagopus) in northern Canada. The mean date of clutch initiation varied up to 16 days over 8 yr and appeared to be related to the timing of snow melt. In one population females laid more synchronously when the onset of breeding was late, but in the other they did not. Laying was not correlated with population density or with proportion of yearling hens in the population. Older hens paired with adult males initiated nesting earlier than yearlings or adult hens paired with yearling males. Females that switched mates from one year to the next laid at the same time as those paired with their previous mates. The timing of clutch initiation or hatch was consistent for individual females from one year to the next in one population, but not in the other. Body size, estimated by wing length, was not correlated with time of laying, but hens with larger body mass laid earlier. Females that nested early laid larger clutches than those laying late. In only 1 yr of 6, a year with very high nest predation, late-nesting hens lost a lower proportion of their clutches. Early-nesting hens hatched more eggs from successful nests than late-nesting hens, but the number of young that fledged and subsequently returned to the population was similar for hens nesting in early, middle, and late reproductive periods. We suggest that hens capable of laying early do so to renest if their clutches are destroyed by predators. Received 29 April 1987, accepted 11 January 1988. TIMING of reproductive events within a breeding season may affect individual fitness and the number of young produced in the population. In birds, females that lay early often have larger clutches than those laying later (e.g. Winkler and Walters 1983), and those that initiate laying late may fledge fewer young (O'Donald et al. 1974). Timing of nesting may also be related to predation rate on clutches. In some species predation is higher on clutches initiated early (e.g. Findlay and Cooke 1982); in others it increases through the season (e.g. Robertson 1973, Wiklund 1984). For any population the optimal time to lay depends on a variety of intrinsic and extrinsic factors that may vary among years. Birds that breed in northern environments are considered to be constrained by the time available to reproduce successfully. Early laying may be prevented by a lack of snow-free habitat (Barry 1962, Holmes 1966, Sealey 1975) or a food shortage (Perrins 1970, Greenlaw 1978, Ewald and Rohwer 1982). Late laying may be constrained by insufficient time for development of young before migration or onset of winter conditions (Barry 1962, Findlay and Cooke 1982). Within the limits set by environmental factors, initiation of laying may be influenced by other extrinsic factors such as population density (Moss et al. 1984) or by intrinsic factors such as the age or experience of either mate (Nol and Smith 1987), the physical condition of a female, genetic effects (e.g., van Noordwijk et al. 1981), or interactions among these factors. We documented the timing of reproduction in two subarctic populations of Willow Ptarmigan (Lagopus lagopus) in Canada. We examined both extrinsic and intrinsic factors that may influence when an individual female began to lay. These include spring weather, population density, age of hen, body size and mass, and experience with mate. Second, we examined the influence of time of clutch initiation on a hen's reproductive success within a season. The Willow Ptarmigan is a territorial, usually monogamous grouse with a holarctic distribution. Females begin to breed as yearlings and are single-brooded, but may renest up to 3 times if the first clutch is lost. Populations undergo cyclic fluctuations with a period of 4-11 yr (Watson and Moss 1979, Myrberget 1984, Hannon and Barry 1986). 330 The Auk 105: 330-338. April 1988 This content downloaded from 157.55.39.186 on Tue, 11 Oct 2016 05:38:32 UTC All use subject to http://about.jstor.org/terms April 1988] Timing of Reproduction in Ptarmigan 331

Female Blue Grouse (Dendragapus obscurus) on Stuart Island, Washington were found to interact aggressively with female dummies in the prelaying period when a taped cackle call was played. Interactions included: tail fanning, wing dragging, everting the white patagium feathers to display a shoulder patch, head bobbing, neck stretching, jump attacking, pecking, and diving attacks. Threatening and aggressive calls included: cackling calls with inflections, a Nee-uk call, and attack and scream whinny calls. The frequency of aggressive interactions was greatest in the latter half of April, a period when hens were selecting nesting sites. The prelaying ranges of 12 hens were mostly mutually exclusive and showed a dispersed distribution relative to each other. However, there were interspaces sufficient for other grouse to nest. We suggest that aggressive behavior and mutual avoidance of females resulted in a dispersed distribution of nest sites. Such spacing should enhance the reproductive fitness of females by reducing predation rates on hens, eggs, and young. Received 24 August 1983, accepted 16 November 1984. THERE has been disagreement among biologists on whether territoriality in birds primarily served to disperse the breeding population (Lack 1966, 1968), or whether, in addition to this spacing function, it regulated numbers by excluding some individuals from securing breeding space (Wynne-Edwards 1962). Even after 20 years, the argument continues (Davies 1978, Patterson 1981, Wittenberger 1981). Recently, the territorial limitation hypothesis has been expanded to include the mutual exclusion of yearling females by other females in polygynous Blue Grouse (Dendragapus obscurus; Zwickel 1972, 1980; Hannon and Zwickel 1979). The primary evidence for surplus nonbreeding females was that, following the removal of localized females in the prelaying period, additional yearling females occupied the vacancies created (Zwickel 1972, 1980). However, this replacement does not constitute unequivocal evidence of socially induced nonbreeding in yearling females, since these females might have bred elsewhere (cf. Watson and Moss 1970). The newcomers could have shifted their ranges to improve their fitness as proposed in the Fretwell-Lucas habitat model (Fretwell and Lucas 1969). Such redistribution is consistent with theoretical considerations that animals should space themselves to reduce predation risk (Taylor 1976). The resolution of this perennial question requires documentation of the dispersion pattern of all females in a population where emigration cannot confound results. We measured aggressiveness and described the distribution of female Blue Grouse on Stuart Island, Washington during the breeding cycle in 1975 and 1976. Our hypothesis was that social interactions between females in the prelaying period resulted in mutually spaced ranges but that the spacing and ensuing social interactions did not prevent any female from nesting. Subordinate females could either nest between the ranges of other females or delay nesting until adults were egglaying and/or incubating their eggs.

The spacing behavior of 58 male Common Capercaillie (Tetrao urogallus) was studied at Varaldskogen in southeast Norway during 1979-1985. Birds captured at leks were equipped with radio-transmitters, and their movements were monitored throughout the year. During spring, males 4 yr old and older occupied exclusive day territories of 10.2-66.0 ha that extended radially from a center at the lek. Adult cocks used the same lek and the same territory during successive years. Among marked birds, the youngest bred at 4 yr. No difference was found in territory size between breeding and nonbreeding adult males. Territories of 3-yr-olds (60.8 ? 10.4 ha) were larger than those of older males (26.3 ? 5.0 ha) and were located farther from the lek. All territories were within a 1.2-km radius of the lek center and were maintained from early April to the end of May. Yearlings and 2-yr-old males were nonterritorial. They moved irregularly among different, neighboring leks, settling near one lek at the end of their second spring season. When associated with one lek, their home ranges were 3-6 times larger than and overlapped peripherally the territories of resident adults. Established subadult and adult males did not change territories when vacancies were created by deaths of older birds, and successful matings were not dependent on occupying a particular territory. Received 16 December 1985, accepted 7 March 1987. THE Common Capercaillie (Tetrao urogallus) is the largest and most sexually dimorphic tetraonid species. Males are polygynous and interact with females only when they visit the lek for a few days to mate in early spring. Based on the spatial arrangements of males at the lek, where individuals are reported to occupy large contiguous or noncontiguous territorial centers of 0.1-0.8 ha (Lumsden 1961, Muller 1979, Hjorth 1985), the mating system is not considered by most authors to be true lekking. Wittenberger (1978, 1981) classified the capercaillie with the forest-dwelling grouse of North America that have dispersed territories. Oring (1982) considered the capercaillie more leklike and classified it as the only tetraonid in an intermediate group, more clustered than the ones above, but less aggregated than his third category that included the prairie grouse of North America and the Eurasian Black-Grouse (Tetrao tetrix). De Vos (1979) also considered the capercaillie in an intermediate type, whereas Wiley (1974) considered it a true lek-forming species. Much of the confusion and difficulty regarding classification of mating systems stems from incomplete knowledge of the spatial and social relationships of the birds when they are not on the display grounds. On the basis of long-term behavioral studies of capercaillie in Sweden, Hjorth (1982) considered how males were spaced around the lek during the day. He noticed that each male departed from the lek in the same direction from which it had arrived and that two males never arrived from, or departed in, the same direction. From this, he suggested that males probably live solitarily in separate home ranges and that these were spaced regularly around the lek. Although no supporting data were presented, Hjorth (1982, 1985) implied further that the home ranges extend up to 2 km from the lek and were used by the males yearround. Our preliminary observations using radiotelemetry (Larsen et al. 1982, Wegge et al. 1982) supported Hjorth's general hypothesis, but suggested that it applied only to adult birds during the breeding season. In other promiscuous North American tetraonids, adult males claim territories during the breeding season, while yearlings are nonterritorial and move about in search of unoccupied areas on which to settle (Bendell and Elliott 1966, Gullion 1967, Ellison 1973, Ballard and Robel 1974, Rippin and Boag 1974, Boag 1976, Herzog and Boag 1978, Zwickel 1980). In the Ruffed (Bonasa umbellus) and the Blue (Dendragapus obscurus) grouse, some adults also may be 481 The Auk 104: 481-490. July 1987 This content downloaded from 207.46.13.166 on Thu, 07 Jul 2016 05:25:25 UTC All use subject to http://about.jstor.org/terms 482 WEGGE AND LARSEN [Auk, Vol. 104 nonterritorial (Lewis and Zwickel 1980, Gullion 1981, Lewis 1984). During spring, nonterritorial yearlings of Spruce (D. canadensis) and Blue grouse and most lek-forming species move considerably longer distances than resident adults, and lek species make temporary visits to neighboring leks (Koivisto 1965, Ballard and Robel 1974, Rippin and Boag 1974, de Vos 1983). We report on the spring spacing pattern of Common Capercaillie males of different age and social status based on radio-tracking 58 individuals during 7 yr in southeast Norway. We discuss the mating system of this species along the continuum from clumped (leks) to dispersed polygyny and report on recruitment and age-related territoriality among males. STUDY AREA AND METHODS The study was conducted during 1979-1985 at Varaldskogen Field Station (60?10'N, 12?30'E) in Hedmark Co. in southeast Norway. Varaldskogen is in the middle boreal zone (Abrahamsen et al. 1977); coniferous forests of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) dominate the vegetative complex. Birch (Betula verrocosa) is the most common deciduous tree, and blueberry (Vaccinium myrtillus) and heather (Calluna vulgaris) dominate the ground layer on undisturbed sites. Intensive logging and forest management have been practiced here for the last 30-40 yr. At the time of our investigation, about 36% of the study area was composed of clear-cuts and spruce and pine plantations up to 8 m in height; 43% of mature, largely undisturbed forest; and 10% of open, treeless peat bogs. The fauna is typical of the middle boreal zone. Because of habitat deterioration and low recruitment, the population of T. urogallus was declining, averaging approximately 0.8 males/km2 in spring in the 40km2 study area (Wegge 1983, 1984, unpubl. data). We captured males at leks and attached radio transmitters to their backs (Brander 1968) with a nylon harness enclosed in silicon rubber to prevent feather and skin abrasion. Transmitters weighed about 100 g (2-3% of body mass), with a transmitting distance of 2-3 km and a battery life of about 700 days. The instrumentation seemed to have no adverse effects because successful matings were observed subsequently among radio-marked individuals of both sexes, and survival rates were high (Wegge 1984). Males were aged according to beak measurements (Moss et al. 1979), using the following age-class intervals based on recaptured birds of known age in the study area. Males with beaks smaller than 23 mm were classified as yearlings (10-11 months old), males with beak depths of 23-25.5 mm were classified as 2-yr-olds (22-23 months), and males with beaks deeper than 25.5 mm were classified as adults (3-yr-old and older birds). Because a number of young males were studied in successive years, 9 known 3-yr-olds could be distinguished from others among the adult age group. Each year during the breeding season, two or more persons were usually present every night on each of 3-6 leks to capture and observe display and breeding activity. We classified radio-equipped males as breeders or nonbreeders on the basis of observed mating performance. Any male that was observed to mate was defined as a breeding male, whether he mated many or few hens. During most years and at most leks, one male dominated the mating. We captured and radio-marked 58 males at 6 leks during the spring seasons of 1979-1985. Several were recaptured during the summer molt and observed in successive seasons. Most telemetry work was carried out at 3 leks; one lek served as the main study population. Active leks (n = 23) in a larger overall study area were spaced regularly, with a mean minimum distance of approximately 2 km (Wegge and Rolstad 1986). The locations of most radio-marked males were determined nearly every morning or late evening in the lek area. During the day their movements and locations were determined 3-7 times/week, except during the seasons of 1982-1984 when some males at two leks were tracked more intensively. Daytime locations, when birds were not on the display ground, were taken between 1000 and 2000, distributed evenly throughout the day. We observed males from 16 April until they ceased to attend leks for morning display. This varied among age groups: most adults attended the leks throughout May, whereas yearlings and most 2-yr-olds usually abandoned the leks 7-10 days earlier. A total of 1,051 positions was recorded when males visited the leks, and 1,238 positions were recorded during daytime when they were away from the lek. Morning locations were used to study the movement of males among and on leks, whereas daytime locations were used to estimate sizes of home ranges and other measures of spacing. We determined the position of each bird by the intersecting compass bearings from two or three elevated vantage points. Approximately 60% of all locations were triangulated to an area of 0.3 ha or less. Locations derived from two compass bearings at close distance were of similar precision. When tracking at longer distances (>500 m), such positions (19%) were less accurate. A disproportionately larger number of the lower-precision fixes were recorded on subadult males. We omitted these when making home-range

A model for grouse and ptarmigan relating the digestibility of their winter foods to their body weights and gut lengths is presented. The observed digestibility of a food depends partly on the "digestive abilities" of the birds eating it, partly on the food's intrinsic digestibility, and partly on daily intakes. Digestive abilities of the birds vary as much intraspecifically as interspecifically. Gut lengths and gizzard weights of gallinaceous birds vary with the diet. Birds that eat coarser, more fibrous foods tend to have bigger guts (Leopold 1953, Lewin 1963, Moss 1972, 1974), presumably because coarser foods demand greater intakes and digestive abilities. The digestibility of foods eaten by different populations should be interpretable from measurements of the birds' guts. This paper provides a simple quantitative model relating the digestibility of a food to its intake and the size of the gut digesting it. Digestibility is an important determinant of nutritive value, food choice, and food intake in vertebrates and, consequently, their foraging behavior. Several factors that might affect digestibility are not included in the model. Not enough is known about their effects on digestibility to include, for example, ambient temperature, state of molt, and reproductive condition. I minimize the effect of such variables by limiting this paper to fully-grown tetraonid birds in autumn and winter, so that food requirements are approximately those for maintenance at 00C. First, one must show how the guts of tetraonids (grouse and ptarmigan) vary in size with the birds' body weight. The equations describing these average relationships are then used to predict gut sizes from the body weight of a population of interest. One can then use the model to infer what the deviations from these average or predicted values imply about the digestibility of foods eaten by the population. Moss and Hanssen (1980) gave an account of digestion in tetraonids. Briefly, the gut is generally full of digesta day and night. The crop is filled with food shortly before going to roost and this store is passed into the gut and digested during the night. After being ground in the gizzard, digesta pass through the small intestine. At the junction of the small and large intestines are two long tubular diverticula, the caeca, into which the more liquid fraction of the chyme is diverted and where it ferments. The more fibrous fraction of the chyme passes by the caecal entrances into the large intestine and is rapidly and regularly egested. The major emptying of the caeca occurs once daily when the bird is about to leave, or has just left, its