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The ongoing and often synergistic effects of habitat loss, invasive species, and climate change pose challenges for conservation and management as widespread species become greatly reduced, sometimes to a single small population. To address this problem, conservation biologists must consider using approaches like translocation to create new populations, reducing the probability of extinction by splitting a population into 2 or more populations in geographically distinct locales. The puaiohi Myadestes palmeri, an endangered Hawaiian forest bird, has a small population size (494; 95% CI: 414-580) and restricted range (~40 km2). One recovery plan objective involves translocating birds to higher elevation Hawaiian Islands. To evaluate translocation scenarios, we built upon previously developed population viability analysis models and considered how translocation regimes (initial harvest/population, number harvested/supplemented per event, harvest/supplementation interval, and length of harvest/supplementation) would affect both original and new populations. Furthermore, we modeled the puaiohi release population under 3 different conditions: a stable population, a predator-controlled environment, and a habitat improved in terms of resource availability. Our results indicated that while translocation offers hope of increasing puaiohi population size and decreasing extinction risk, success will depend on conditions at the release site. Furthermore, harvest and rearing of eggs to the juvenile stage or re-establishment of a captive breeding program may be necessary to provide enough birds to translocate, as the current wild population may not be productive enough to sustain levels of harvest necessary to successfully establish a new population.

SummaryWith rapid urbanization worldwide, most people now live in cities, but the effects of urbanization on knowledge about the natural environment is not well studied. Due to the importance of Cymbidium to Chinese traditional culture, we tested how urbanization influences the distribution of orchid knowledge across various knowledge domains at risk of loss due to declining orchid populations. Participants in the Cymbidium trade were interviewed in three distinct urbanization-level jurisdictions in Sichuan, China: Puge (low urbanization), Huili (moderate urbanization) and Chengdu (high urbanization). Using photographic cue-cards of nine Cymbidium taxa, we assessed aggregate and specific knowledge held by 91 orchid collectors/traders across the urbanization gradient. Contrary to expectations, we found that urbanization and orchid knowledge were positively related, but this varied by knowledge type, with moderate urbanization showing significantly higher knowledge in two domains. Our findings suggest that a generalizable understanding of how urbanization affects knowledge must account for differences in knowledge types and geographic/cultural scales, with implications for biocultural diversity conservation in an increasingly urban world.

The Nightingale Reed-Warbler (Acrocephalus hiwae), a critically endangered songbird, is the last remaining of four reed-warbler species that once inhabited the Mariana Islands. The most recent population estimate for the species is 2915-3742 individuals distributed over the islands of Saipan (n = 2742, 95% CI = 1686-3956) and Alamagan (n = 946, 95% CI = 173-1000), which represents a significant decline for the species on Saipan. Though data on life history parameters such as survival rates are not widely available, other parameters such as clutch size and nest success have been studied. Given the extirpation of three of the four reed-warbler species from the Mariana Islands, the recent significant decline of the larger Saipan population, and the increasing threats faced by the species, it is critical to determine what additional life history information is needed to aid management decisions. Using Vortex, we developed stochastic population models to represent current reed-warbler population dynamics and used sensitivity analysis to identify the life history parameters to which the model was most sensitive. Baseline models without inbreeding indicated declines of the Nightingale Reed-Warbler populations on Saipan and Alamagan, as well as of the overall population. The inclusion of inbreeding further increases the modeled rate of population decline. Parameters such as initial population size, carrying capacity, and male survival have relatively little influence on reed-warbler population models, while female and juvenile survival and, to a lesser degree, fecundity measures, exhibit strong influences on the species' population dynamics. We recommend effort be placed on collecting updated survival data for all life stages, but particularly for females and juveniles. Given model predictions of vulnerability to extinction, we recommend management actions that may increase survival rates of juveniles and females.

The endangered Puaiohi (Myadestes palmeri) endemic to Kaua‘i is the island’s only remaining native thrush. Given its small population of ~500 birds, it is essential to understand conditions that affect the species’ recruitment and survival. Previous observations of Puaiohi suggested that weather may influence nest success and productivity, but no studies investigated this relationship empirically. Our goal was to investigate potential links between weather conditions (precipitation and temperature) in the Puaiohi’s range (~20 km2) and several measures of reproductive success, using published data from 1996–1998 and new data collected by the Kaua‘i Forest Bird Recovery Project from 2007–2009. Total rainfall in the previous wet season strongly and positively correlated with the majority of the nest success variables (three of four). Mean rainfall during the breeding season correlated positively with reproductive effort (attempts/season and length of breeding season) and with total reproductive outp...

Biological and cultural diversity are integrally linked, yet understanding how culture impacts biological extinction is limited. The orchid richness of Southwest China’s Sichuan Province is the second highest in China, but price speculation and overharvest have resulted in significant recent orchid population collapses. Due to the importance of Cymbidium orchids to Han Chinese traditional culture, this study sought to test how the decline of these populations related to four different orchid knowledge domains and various socio-demographic variables on the local scale. Interviews were conducted in eight villages in rural Liangshan Yi Autonomous Prefecture: four Han-majority and four Yi-majority. Using photographic-cue-cards of nine Cymbidium taxa, aggregate- and specific-knowledge were assessed of 15 randomly selected individuals per village (120 total), in three age groups. Results showed that species decline negatively impacted culturally important knowledge of orchids across all knowledge domains, regardless of pre-extinction orchid rarity, and regardless of socio-demographic variables. Following population collapse, the decline in perceived economic value of orchid knowledge outweighed the influence of cultural veneration that traditionally drove Cymbidium knowledge acquisition. These findings highlight how biodiversity loss not only negatively affects the ecology and environment, but also culture, with profound implications for cultural resilience and biocultural diversity conservation efforts.

The island of Kaua‘i, Hawai‘i has several remaining populations of endangered, endemic Hawaiian petrels (Pterodroma sandwichensis) and Newell's shearwaters (Puffinus newelli) that would be threatened by the presence of predatory mongooses (Herpestes javanicus). Despite over 200 putative sightings, 1 road-kill and 2 recent captures, it is not clear if mongooses have actually become established on Kaua‘i. Comparing road transects on three Hawaiian islands, we found mongooses present on O‘ahu and Maui where they are known to occur and no evidence of significant populations on Kaua‘i. Three population scenarios are presented that would account for the three specimens, the past sightings, and the absence of sightings on our transects on Kaua‘i.

The miconia (Miconia calvescens) invasion of the East Maui Watershed (EMW) started from a single introduction over 40 yr ago, establishing a nascent patch network spread across 20,000 ha. In 2012, an accelerated intervention strategy was implemented utilizing the Herbicide Ballistic Technology (HBT) platform in a Hughes 500D helicopter to reduce target densities of seven nascent patches in the EMW. In a 14-mo period, a total of 48 interventions eliminated 4,029 miconia targets, with an estimated 33% increase in operations and 168% increase in recorded targets relative to the adjusted means from 2005 to 2011 data (prior to HBT adoption). This sequence of interventions covered a total net area of 1,138 ha, creating a field mosaic of overlapping search coverage (saturation) for each patch (four to eight interventions per patch). Target density reduction for each patch fit exponential decay functions (R2 > 0.88, P < 0.05), with a majority of the target interventions spatially assigned to the highest saturation fields. The progressive decay in target density led to concomitant reductions in search efficiency (min ha−1) and herbicide use rate (grams ae ha−1) in subsequent interventions. Mean detection efficacy (± SE) between overlapping interventions (n = 41) was 0.62 ± 0.03, matching closely with the probability of detection for a random search operation and verifying imperfect (albeit precise) detection. The HBT platform increases the value of aerial surveillance operations with 98% efficacy in target elimination. Applying coverage saturation with an accelerated intervention schedule to known patch locations is an adaptive process for compensating imperfect detection and building intelligence with spatial and temporal relevance to the next operation.

Arctic terns Sterna paradisaea are noted for their extraordinary migration between Arctic and sub-Arctic breeding grounds and Antarctic wintering areas. Until recently, few data existed to document this migration, and none existed for North Pacific breeders. In this study, we tracked 6 Alaskan Arctic terns tagged with combined light geolocation and saltwater immersion tags through their fall migration. During fall 2007, these birds used several highly productive stopover locations to refuel during their southward migration: the California Current, the northern and southern Humboldt Current, and the Patagonian Shelf. At least 3 of the birds went on to win- ter in the Weddell Sea region of Antarctica, where Arctic terns from several Atlantic populations are also known to winter. Analysis of the first ever post-breeding behavioral data collected on this species showed that the birds foraged extensively in these staging areas, spending more time for- aging on days when they were located within staging areas during the fall migration. We also found that the birds were exclusively diurnal foragers, spending their nights standing out of the water and/or flying. Arctic terns likely face strict time constraints throughout the migration, timing stopovers to match production while simultaneously aiming to arrive at the wintering grounds with sufficient time remaining to complete the winter molt before returning north. Ecological dis- turbance at any of these locations could have serious consequences for many birds. Further, pre- dicted effects of climate change in the Weddell Sea region could have repercussions throughout the global Arctic tern population.

We developed an epidemiological model of avian malaria (Plasmodium relictum) across an altitudinal gradient on the island of Hawaii that includes the dynamics of the host, vector, and parasite. This introduced mosquito-borne disease is hypothesized to have contributed to extinctions and major shifts in the altitudinal distribution of highly susceptible native forest birds. Our goal was to better understand how biotic and abiotic factors influence the intensity of malaria transmission and impact on susceptible populations of native Hawaiian forest birds. Our model illustrates key patterns in the malaria-forest bird system: high malaria transmission in low-elevation forests with minor seasonal or annual variation in infection; episodic transmission in mid-elevation forests with site-to-site, seasonal, and annual variation depending on mosquito dynamics; and disease refugia in high-elevation forests with only slight risk of infection during summer. These infection patterns are driven by temperature and rainfall effects on parasite incubation period and mosquito dynamics across an elevational gradient and the availability of larval habitat, especially in mid-elevation forests. The results from our model suggest that disease is likely a key factor in causing population decline or restricting the distribution of many susceptible Hawaiian species and preventing the recovery of other vulnerable species. The model also provides a framework for the evaluation of factors influencing disease transmission and alternative disease control programs, and to evaluate the impact of climate change on disease cycles and bird populations.

Many species of tropical seabirds rely on subsurface predators such as tuna and dol- phins to drive prey close to the ocean's surface. We observed seabird foraging events from fishing vessels around the island of Oahu, Hawaii, to determine the prevalence and relative importance of different subsurface predators to seabird foraging. Sixty-nine seabird foraging events were observed, in 62 of which the presence and/or identity of subsurface predators could be determined. Of those 62, all but two involved subsurface predators and accounted for 99.8% of all foraging birds. Skipjack tuna Katsuwonus pelamis were the predominant (81%) subsurface predator involved in seabird feed- ing events, with odontocetes Stenella attenuata and Pseudorca crassidens (8%), mahimahi Coryphaena hippurus (6%), and yellowfin tuna Thunnus albacares (2%) being less common. Wedge- tailed shearwaters Puffinus pacificus and brown noddies Anous stolidus foraged in association with tuna schools more often than would be expected by chance alone. Red-footed boobies Sula sula, in contrast, did not associate with any subsurface predator in greater proportion than what would be expected by chance. Nine additional seabird species were observed foraging in association with sub- surface predators, but not in numbers large enough for statistical analysis. This study highlights the value of regional investigations able to uncover the variable nature of seabird-subsurface-predator associations. The finding that, in Hawaii, at least 2 species of seabirds showed tight dependence on tuna underlines the need for tuna fishery management to address the potential indirect ecological effects of fishing.

The past quarter century has seen an unprecedented increase in the number of new and emerging infectious diseases throughout the world, with serious implications for human and wildlife populations. We examined host persistence in the face of introduced vector-borne diseases in Hawaii, where introduced avian malaria and introduced vectors have had a negative impact on most populations of Hawaiian forest birds for nearly a century. We studied birds, parasites, and vectors in nine study areas from 0 to 1,800 m on Mauna Loa Volcano, Hawaii from January to October, 2002. Contrary to predictions of prior work, we found that Hawaii amakihi (Hemignathus virens), a native species susceptible to malaria, comprised from 24.5% to 51.9% of the avian community at three low-elevation forests (55–270 m). Amakihi were more abundant at low elevations than at disease-free high elevations, and were resident and breeding there. Infection rates were 24–40% by microscopy and 55–83% by serology, with most infected individuals experiencing low-intensity, chronic infections. Mosquito trapping and diagnostics provided strong evidence for year-round local transmission. Moreover, we present evidence that Hawaii amakihi have increased in low elevation habitats on southeastern Hawaii Island over the past decade. The recent emergent phenomenon of recovering amakihi populations at low elevations, despite extremely high prevalence of avian malaria, suggests that ecological or evolutionary processes acting on hosts or parasites have allowed this species to recolonize low-elevation habitats. A better understanding of the mechanisms allowing coexistence of hosts and parasites may ultimately lead to tools for mitigating disease impacts on wildlife and human populations.

Lyme disease is a zoonosis transmitted by ticks and caused by the spirochete Borrelia burgdorferi sensu lato. Epidemiological and ecological investigations to date have focused on the terrestrial forms of Lyme disease. Here we show a significant role for seabirds in a global transmission cycle by demonstrating the presence of Lyme disease Borrelia spirochetes in Ixodes uriae ticks from several seabird colonies in both the Southern and Northern Hemispheres. Borrelia DNA was isolated from I. uriae ticks and from cultured spirochetes. Sequence analysis of a conserved region of the flagellin (fla) gene revealed that the DNA obtained was from B. garinii regardless of the geographical origin of the sample. Identical fla gene fragments in ticks obtained from different hemispheres indicate a transhemispheric exchange of Lyme disease spirochetes. A marine ecological niche and a marine epidemiological route for Lyme disease borreliae are proposed.

Our paper (Duffy & Meier 1992) was an effort to measure the recovery of Appalachian forests understory herbs following deforestation. We expected herbal recovery to parallel that of the trees, but our results showed a dramatic difference between primary and secondary forests in the extent of herbaceous cover and species richness. Over time, the two forest types should converge in herb characteristics, but our data show no such trend through 87 years. We speculated that recovery of the understory community would take several centuries or might not occur at all. We noted that such loss of diversity and failure to recover would appear to be at variance with the requirements of the National Forest Management Act of 1976. Our article was reported on by The Associated Press, CNN, The Atlanta Constitution, and The New York Times and has been used by citizens' groups opposed to clear-cutting in the Southern Appalachians. This in turn appears to have upset some foresters and Forest Service researchers. Johnson et al. admit that they wrote to Conservation Biology because our original article was "... widely reported in the popular press" and because some of our comments in the press were "... especially troubling." Within the limits of available space, I have tried to address the main scientific points raised by Johnson et al.; other points have already been addressed in my response to the letters of Steinbeck and of Elliott and Loftis. I suspect that many of the points raised by Johnson et al. would have been resolved had they taken into account the following: that we worked on understory herbs, not on all herbs; that we defined primary forest as we did (see below); and that we used a diversity, rather than a species-approach, to the problem. Johnson et al. claim that, "The primary forest sites studied by Duffy and Meier were not undisturbed." We

The risk for human infection with Lyme disease appears linked to the abundance of infected vector ticks, principally Ixodes dammini Spielman, Clifford, Piesman & Corwin, in the eastern United States. Habitat destruction by burning, although not well studied, has long been considered as an effective alternative to synthetic insecticides as a means of reducing tick populations. We evaluated the effect of a single spring burning of the woodland understory on the transmission risk of Lyme disease spirochetes (Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner) on Shelter Island, Long Island, NY. Following a burn in early April 1991, the abundance of nymphal I. dammini was 49% lower in the burned portion of a woodlot compared with the unburned portion. However, risk of encountering nymphs infected with B. burgdorferi remained similar in both burned and unburned woods. It is suggested that burning vegetation may disproportionately kill deer-derived rather than rodent-derived nymphs, significantly reducing tick abundance without affecting transmission risk.

Infectious diseases now threaten wildlife populations worldwide but population recovery following local extinction has rarely been observed. In such a case, do resistant individuals recolonize from a central remnant population, or do they spread from small, perhaps overlooked, populations of resistant individuals? Introduced avian malaria (Plasmodium relictum) has devastated low-elevation populations of native birds in Hawaii, but at least one species (Hawaii amakihi, Hemignathus virens) that was greatly reduced at elevations below about 1000 m tolerates malaria and has initiated a remarkable and rapid recovery. We assessed mitochondrial and nuclear DNA markers from amakihi and two other Hawaiian honeycreepers, apapane (Himatione sanguinea) and iiwi (Vestiaria coccinea), at nine primary study sites from 2001 to 2003 to determine the source of re-establishing birds. In addition, we obtained sequences from tissue from amakihi museum study skins (1898 and 1948–49) to assess temporal changes in allele distributions. We found that amakihi in lowland areas are, and have historically been, differentiated from birds at high elevations and had unique alleles retained through time; that is, their genetic signature was not a subset of the genetic variation at higher elevations. We suggest that high disease pressure rapidly selected for resistance to malaria at low elevation, leaving small pockets of resistant birds, and this resistance spread outward from the scattered remnant populations. Low-elevation amakihi are currently isolated from higher elevations (> 1000 m) where disease emergence and transmission rates appear to vary seasonally and annually. In contrast to results from amakihi, no genetic differentiation between elevations was found in apapane and iiwi, indicating that slight variation in genetic or life-history attributes can determine disease resistance and population recovery. Determining the conditions that allow for the development of resistance to disease is essential to understanding how species evolve resistance across a landscape of varying disease pressures.

Nymphal Ixodes scapularis Say, the vector of Lyme borreliosis, was most common in forested areas across Shelter Island, Suffolk County, New York, and least common in xeric habitats such as beach and grassland. At the scale of individual house yards, nymphs were most common at wooded edges of property and least common on lawns. The abundance of ticks at yard edges was positively correlated with numbers on lawns and in landscaping, suggesting that tick abundance in woods affects abundances in adjacent yards. Because 57% of all yard area is adjacent to woodlands on Shelter Island, public health efforts to reduce tick populations in wooded areas should supplement efforts by individual yard owners to decrease risk. Methods of tick control for woodlands should also be evaluated for their effect on tick populations in adjacent yard habitats.

Nymphal Ixodes scapularis Say deer ticks were collected at 22 parks or other natural areas on Long Island, New York, to examine the relationship between tick populations and geographic position, size of area, presence of white-tailed deer, Odocoileus virginianus (Zimmerman), and numbers of human Lyme disease cases in adjacent communities. Nymphal ticks were 93% less abundant when deer were absent and were also less common in smaller natural areas. Geographic position on Long Island was not important. Tick numbers were significantly correlated with human Lyme disease incidence in adjacent townships. A second survey of larval ticks from five areas where deer were absent and six where deer were present found larvae present at four of the five sites without deer, but at only 2% of the levels found where deer were present. These results suggest that populations of I. scapularis can occur and reproduce in the absence of white-tailed deer, so that eradication of all deer would greatly reduce, but not eliminate, all risk of Lyme disease.

Based on winter flagging experiments on Long Island, NY, adult Ixodes scapularis Say have an apparent threshold of questing activity at 4 degrees C. This threshold should be incorporated into public education efforts because the public may be at risk of contracting Lyme disease any time during the winter when temperatures exceed 4 degrees C.

On 29 November 2004, a male Po?ouli Melamprosops phaeosoma died of what was effectively old age while in captivity in Hawai?i. The only two other known birds of this species, both at least five years old, have not been seen since 2003 and the species is now presumed extinct (Anon. 2004). With the passing of the Po?ouli, it is appropriate to ask what Hawai?i?s latest loss tells us about the state of terrestrial conservation and conservation science in the archipelago. Is this representative of conservation effectiveness in Hawai?i or merely an unlucky fluke?

We used an artificial environment at Sea World, Inc, San Diego, to study underwater foraging behavior of alcids. Larger birds dove longer and had greater wingbeat frequencies. The pigeon guillemot Cepphus columba was the only species to use both feet and wings for propulsion; all others used just wings. Aggressive interactions underwater were common. Competition among alcids in the wild may occur primarily underwater, and artificial environments may be the best means to study such interactions.

Breeding attempts by the African penguin Spheniscus demersus at a colony on Marcus Island, Saldanha Bay, South Africa, decreased by 14% per year during 1979–1985. Annual adult survival was 33·3–70·4%. Nesting success at Marcus Island was similar to that at other African penguin colonies of St Croix and Dassen islands and at colonies in other areas of other penguin species not undergoing population decreases. Minimum survival of juveniles in the first year of life was only 4% of the level needed to sustain a stable population.

Summary Duffy, D. C. 1987. Ecological implications of intercolony size-Variation in Jackass Penguins. Ostrich 58: 54–57. The culmen length of courting adult male Jackass Penguins Spheniscus demersus varied between colonies, with the largest culmens in southern Namibia and east of Cape Point, South Africa. Taxonomic distance, a single measure combining several morphological characters, was significantly and positively correlated with geographic distance between colonies. Population changes between 1956 and 1978 were not significantly correlated with male mandible or flipper length, suggesting that adult size cannot be used as an index of population changes at individual colonies. Possible dispersal may complicate attempts to use changes at individual colonies as indices of changes in fish stocks of surrounding waters.

Summary Duffy, D. C., Heseltine, S. & La Cock, G. D. 1987. Food size and aggressive interactions between two species of gulls: an experimental approach to resource partitioning. Ostrich 58: 164–167. In feeding experiments with different sizes offish, Hartlaub's Gulls Larus hartlaubi reached prey first, but lost larger items to the larger, dominant Kelp Gull L. dominicanus. Hartlaub's Gulls took longer than Kelp Gulls to consume prey of the same size.

Line transects from boats were conducted during 1984 and 1985 to determine African Penguin (Speniscus demersus) distribution in the South African Cape waters. Range limits for breeding birds were derived from information on penguin travelling speeds and durations of foraging trips. Over 50% of all penguins considered to be non-breeding occurred within 20 km of the coast whilst over 50% of all breeding birds occurred within 3 km of the coast. Penguin density decreased with increasing distance offshore. The most frequently encountered penguin group size was one with larger groups decreasing in incidence according to a power curve decay. There was no difference in the frequency of occurrence of different group sizes between breeding and non-breeding penguins, nor did group size distribution change with distance offshore. Data on African Penguin distribution at sea collected in 1984 and 1985 was not discernably different to equivalent data collected between 1954 and 1974. The composition of penguin group size was also the same during both periods.

Densely nesting Guanay Cormorants (Phalacrocorax bougainvillii), Peruvian Booby (Sula variegate), and Peruvian Brown Pelican (Pelecanus occidentalis thagus) deserted eggs and young in response to high densities of argasid ticks (Ornithodoros amblus). Alternative causes of desertion such as human disturbance, predation, disease, heat, and food shortage did not fit the evidence. Tick predators were less effective at controlling ticks than were frequent human harvestings of guano. A review of the avian and medical entomological literature indicates that ticks and other ectoparasites may be strong determinants of nesting success and of nest structure and duration of use.

1. 1. Cerium 141 and carmine red dye were used to measure rates of passage through the digestive tracts of captive Jackass Penguins (Spheniscus demersus) . 2. 2. Mean excretion times were 11.65 hr for 141 Ce and 10.15 hr forcarmine. Both markers began to appear within 2 hr of ingestion and were still being excreted after 24 hr. 3. 3. Cumulative rates of excretion were generally similar, although initial excretion of carmine was higher. 4. 4. Comparison with studies of clearance rates of food from the proventriculus and ventriculus allow comparison of residence times in different parts of the digestive tract.

Humboldt Penguins diving in clear water in Chile had two distinct behaviours; short dives\((\bar x = 13.3 s)\) where the birds remained within a metre of the surface and bounce dives, where the penguins descended the water column to the sea bed where they immediately returned to the surface. Here, dive time was correlated with water depth. Stomach pumped penguins had eaten predominantly pelagic school fish,Scomberesox, Engraulis andSardinops. Most prey (94 %) had been seized from below. We suggest that short, shallow dives are typical of travelling penguins. Bounce dives, however, would enable foraging penguins, which have an enhanced binocular field above the line of the bill, to perceive surface-swimming prey more easily because silvery clupeid fish appear as silhouettes.

Summary Duffy, D. C. & La Cock, G. D. 1985. Partitioning of nesting space among seabirds of the Benguela upwelling region. Ostrich 56:186-201. An examination of nesting habitats used by the four main species of seabirds nesting on southern African islands (Jackass Penguin Spheniscus demersus, Cape Cormorant Phalacrocorax capensis, Bank Cormorant P. neglectus and Cape Gannet Morus capensis) revealed relatively minor differences and extensive overlaps between species, primarily in subcolony size, steepness of nesting substratum, and proximity to cliffs. A weak dominance hierarchy existed; gannets could displace penguins, and penguins could displace cormorants. This hierarchy appeared to have little effect on partitioning of nesting space. Species successfully defended occupied sites in most cases of interspecific conflict, suggesting that site tenure by one species could prevent nesting by another. The creation of additional nesting space on Namibian nesting platforms did not increase guano harvests, sugges...

The roles of the El Nino phenomenon, a cessation of upwelling, and of human fishing in limiting populations of Peruvian guano birds (Guanay cormorant Phalacrocorax bougainvillii, Peruvian booby Sula variegata, and Peruvian brown pelican Pelecanus occidentalis thagus) were investigated using historical records and the scientific literature. In normal years, the combined populations of the three species showed an 18% increase per year. El Ninos occurred at approximately five-year intervals and caused a population decrease of 17% and 35% desertion of nesting areas. In severe El Ninos at approximately 12-year intervals, there was a mean decrease of 47% and complete nesting failure. El Ninos varied in severity and a possible explanation is presented. In non-El Nino years, commercial fishing did not directly control bird populations through starvation of adults or drowning in nets. Increased commercial fishing apparently led to decreased nesting success: the greater the quantity of fish landed, the lower the percentage increase of the bird population that year. Short-lived, heavily-fished species such as anchoveta are in constant danger of population collapse during years of occasional, unpredictable reproductive failure. Bird populations could be maintained as buffers to prevent terminally-destructive overfishing by humans.

Observations of foraging patterns are essential to understanding the energetic ecology of marine animals. However, direct observations are not often feasible in the field because most foraging takes place below the sea surface or at great distances from land. Attachment of data-recording devices to animals can greatly facilitate the collecton of meaningful data. Devices are being used to an increasing extent on marine mammals (Kooyman et al. 1976, Ray et al. 1978), birds (Kooyman et al. 1971, 1982, Adams and Brown 1983, Lishman and Croxall 1983, Wilson and Bain 1984a, b), reptiles (Stoneburner 1982), and fish (Voegeli and Piucock 1980, Priede 1983a). These devices may supply data upon recovery (e.g., Kooyman et al. 1971, 1982) or through telemetry to local receivers (e.g., Voegeli and Piucock 1980, Priede 1983a, b) or to orbiting satellites (Stoneburner 1982). The effects of instrument mass and harness attachment on land animals are considered to have the potential of affecting the outcomes of experiments and observations (Dumke and Pils 1973, Gilmeretal. 1974, Perry 1981, Perryetal. 1981). However, the effects of devices on marine animals, which live in a much more viscous medium than air, have not been evaluated. In this study we investigated the effects of attached instruments on the foraging activity of the African Penguin (Spheniscus demersus). We show that instrument size may adversely affect foraging behavior, but that data obtained using devices of varying sizes can be used to back-calculate true foraging parameters of free-swimming penguins without devices. Data-recording devices are especially important in studies of free-swimming penguins because these birds are inconspicuous on the surface of the water and are not visible during their frequent traveling and foraging dives. Instruments have been constructed to record speed (Wilson and Bain 1 984b), foraging range (Wilson and Bain 1984b, Wilson and Achleitner 1985), dive time (Trivelpiece et al., in press), dive frequency and depth (Kooyman et al. 1982, Wilson and Bain 1984a). Results show that African Penguins are capable of sustained speeds of at least 7.5 km/h (Nagy et al. 1984) and that other penguin species forage at depths exceeding 200 m (Kooyman et al. 1982). Measurements of foraging distance have also been used to estimate the energy cost of swimming and to construct energy budgets (Nagy et al. 1984). Devices may affect performance in two ways. The mere presence of a device may modify behavior. However, in our experience with penguins this does not appear to be important; after a short period of adjustment, African Penguins with devices continued their normal nesting activity and entered the sea to forage with frequencies similar to control birds (Wilson and Bain 1984a, b). Second, the mass or drag of a device may retard swimming speed, thus reducing dive depth, foraging range, and the number of prey encountered. Instrument mass in itself probably does not adversely influence foraging behavior because attached devices are usually .05) which suggests that the smallest meters had virtually no effect on foraging behavior. On the other hand, two penguins fitted with an electronic distance meter 14.6% of penguin

1. Ticks (Ornithodoros capensis Neumann) were most abundant on incubating host African penguins (Spheniscus demersus Linnaeus) at 24.00 hours and least abundant during 09.00-12.00 hours during 4 day periods in May and October at 3 h intervals. 2. Ticks were three times as abundant in May, the start of the breeding season, as in October, at its end. 3. Air temperature and humidity appear less important than light levels in determining tick activity. 4. The degree of tick parasitism of breeding seabirds is best studied at night.

Il semble y avoir une tres grande difference dans le temps de retention des parties dures des proies ingerees par les oiseaux marins, les becs d'encornet persistant dans l'estomac beauoup plus long temps que les parties dures des autres proies. Il faut tenir compte de ces faits pour etudier le regime alimentaire de ces oiseaux

Pellets of Cape Cormorants (Phalacrocorax capensis) are cast daily and can be used to determine prey species through identification of otoliths and other indigestible parts. Experiments in captivity indicate that some otoliths may be partially or entirely digested, making it impossible to estimate the original size or number of fish ingested per meal or per day. Birds of various species regurgitate casts or pellets of indigestible material (Knight 1964). Pellets of cormorants could be useful for study- ing diets of these birds because sampling is non-destructive and large samples can be ob- tained with little disturbance to the birds (Ain- ley et al. 198 1). Crystals of fish eyes taken from pellets might be counted to estimate daily food intake (Jordan 1959, Schlatter and Moreno 1976) and otoliths could be useful in identi- fying the species and sizes of fish consumed by the birds. However, certain aspects of pellet produc- tion require investigation before pellets can be used for either quantitative or qualitative stud- ies. How frequently are pellets cast? Does a pellet (accurately) reflect a meal or a bird's daily consumption of food? Do otoliths remain unchanged while residing in a bird's stomach, so that otoliths can be used to estimate the sizes of the fish eaten? How long do otoliths persist in a bird's stomach? We report here on studies designed to answer these questions, us- ing information obtained from pellets pro- duced by captive Cape Cormorants (Phalacro- corax capensis). METHODS Seven adult Cape Cormorants were taken from Dyer Island (34"4 1 'S, 19"15'E), Cape Province, South Africa, on 19 November 198 1. The birds were transported overnight by sea to Cape Town and placed in cages. They were kept in the cages for six weeks until their weights sta- bilized and they became accustomed to cap- tivity. Birds were grouped in two cages of two individuals and one cage of three, because they refused to eat if kept separately. During the experimental period, the birds were fed com- mercially obtained horse mackerel (Trachurus cupensis; 140 mm) and cape anchovy (En- gruulis capensis; 120 mm). Birds were fed twice daily (10:00 and 16:OO) by throwing them fish, until satiated. Cages were carefully searched for pellets at 08:00, after which the birds were weighed. Recovered pellets were measured to the nearest millimeter for maximum length and their volumes determined by displacement in water. Each pellet was then cut open and any otoliths and eye crystals extracted and count- ed. Three experiments were carried out: Experiment one. Does the composition of pellets accurately reflect daily food intake? We counted the number of otoliths and eye crystals in pellets in relation to the number of fish con- sumed. The size and number of fish fed to each bird in each cage were noted. The number of pellets produced one day later was recorded for each cage. We combined the number of fish fed and number of pellets produced within each cage, since we did not know which bird pro- duced each pellet within a cage. If pellets per- fectly reflected fish intake, and if pellets are produced daily, the number of otoliths and eye crystals should have been twice the number of fish consumed the day before. Experiment two. Can otolith size be used to

Food transit rates in the Jackass Penguin (Spheniscus demersus), a piscivorous seabird, are slower (Duffy et al. 1985) than rates of birds with other diets (Warner 1981). However, digestive performance by the Jackass Penguin may not be typical of fish-eating seabirds. Food transit rates through the digestive tracts of volant seabirds might be faster than those of flightless species, since meals would represent a considerable addition to the body mass that would have to be lifted during flight. Rapid digestion and extraction of water from prey would reduce meal-mass (Ashmole 1971). We tested this hypothesis by comparing transit rates through the digestive tracts of Cape Gannets (Morus capensis) with existing data on Jackass Penguins and Cape Gannets (Davies 1956, Duffy et al. 1985).

In foraging groups in the Long Island Sound area of the eastern United States, Roseate Terns Sterna dougalli plunged for longer periods and from greater heights than did Common Terns Sterna hirundo. Roseate Terns were rarer than expected in dense feeding groups where they tended to occur at the peripheries but they were more common than expected in more dispersed groups. Roseates were also more successful per plunge than were Common Terns in dispersed groups. The species appeared to partition food on the basis of patchiness: Common Terns were more successful in large groups over presumably larger patches of prey while Roseate Terns had more success in smaller groups feeding on more dispersed prey.

Dans certains sites ces oiseaux (Sula dactylatra et S. nebouxii) nidifient proches l'un de l'autre, dans d'autres sites leur lieu de nidification est different et la competition faible