Search

Applied ecologists routinely use demographic models to predict population trajectories. Survival rates throughout the life cycle, which are required for these models, are often difficult to obtain, especially for long-lived or mobile species. Detailed information for pre-adult age classes in particular is often lacking. Using a 20-year dataset from several hundred individuals, we used Markov chain Monte Carlo methods to fit hierarchical models that describe survival rates for both adult and sub-adult Hawaiian stilts Himantopus mexicanus knudseni, an endangered island endemic. We constructed the complete-data likelihood and used data augmentation to estimate missing values and incorporate data that were not collected during formal sampling. Survival estimates were lower and more uncertain during the first 2 months of life compared with the remainder of the first year. The probability of first-year survival averaged 0.55 (95% credibility interval: 0.07-0.90), but varied considerably among cohorts from different years and islands. Probability of adult annual survival differed little between females (0.79; 0.71-0.86) and males (0.80; 0.72-0.87), but increased as birds aged from 1 to 20 years (0.77-0.85). Our analysis confirms that earlier work, despite being based on few data, provided good point estimates for survival rates. Our new analysis, however, provides the first comprehensive assessment of uncertainty in survival rates and detailed information on the nature of variation in first-year and adult survival. This information will help inform new demographic models and can be used to guide management actions. [ABSTRACT FROM AUTHOR]

Whimbrels ( Numenius phaeopus) are large shorebirds that breed in two geographically disjunct regions in the North American Subarctic and Arctic. Since the early 1970s, the nesting distribution of Whimbrels in the Subarctic near Churchill, Manitoba, Canada has changed, and an area of historic breeding importance was no longer used as nesting habitat in 2008. We compared aerial photography of the 2.55 km area from 1973 to 1986, to high-resolution satellite imagery from 2006 to assess structural habitat change. Comparison of the three time-period imagery showed that over the 33-year span shrubs and trees increased in cover by 12.6 and 6.9 %, respectively, whereas other vegetation, including lichen, decreased by 19.1 %. This localized evidence of shrub and tree encroachment is accompanied by a decline in Whimbrel nesting densities from 17-19 pairs (max. 7.45 pairs/km) in 1973 and 1974, to 1-2 pairs (max. 0.78 pairs/km) in 2007, and 0 pairs in 2008. Change in vegetation structure has important implications for the long-term viability of Subarctic and Arctic breeding shorebird populations. [ABSTRACT FROM AUTHOR]

Mechanistic insights and predictive understanding of the spatial distributions of foragers are typically derived by fitting either field measurements on intake rates and food abundance, or observations from controlled experiments, to functional response models. It has remained unclear, however, whether and why one approach should be favoured above the other, as direct comparative studies are rare., The field measurements required to parameterize either single or multi-species functional response models are relatively easy to obtain, except at sites with low food densities and at places with high food densities, as the former will be avoided and the second will be rare. Also, in foragers facing a digestive bottleneck, intake rates (calculated over total time) will be constant over a wide range of food densities. In addition, interference effects may depress intake rates further. All of this hinders the appropriate estimation of parameters such as the 'instantaneous area of discovery' and the handling time, using a type II functional response model also known as 'Holling's disc equation'., Here we compare field- and controlled experimental measurements of intake rate as a function of food abundance in female bar-tailed godwits Limosa lapponica feeding on lugworms Arenicola marina., We show that a fit of the type II functional response model to field measurements predicts lower intake rates (about 2·5 times), longer handling times (about 4 times) and lower 'instantaneous areas of discovery' (about 30-70 times), compared with measurements from controlled experimental conditions., In agreement with the assumptions of Holling's disc equation, under controlled experimental settings both the instantaneous area of discovery and the handling time remained constant with an increase in food density. The field data, however, would lead us to conclude that although handling time remains constant, the instantaneous area of discovery decreased with increasing prey densities. This will result into highly underestimated sensory capacities when using field data., Our results demonstrate that the elucidation of the fundamental mechanisms behind prey detection and prey processing capacities of a species necessitates measurements of functional response functions under the whole range of prey densities on solitary feeding individuals, which is only possible under controlled conditions. Field measurements yield 'consistency tests' of the distributional patterns in a specific ecological context. [ABSTRACT FROM AUTHOR]

Understanding the relative contributions of intrinsic and extrinsic factors to population structure and genetic diversity is a central goal of conservation and evolutionary genetics. One way to achieve this is through comparative population genetic analysis of sympatric sister taxa, which allows evaluation of intrinsic factors such as population demography and life history while controlling for phylogenetic relatedness and geography. We used ten conserved microsatellites to explore the population structure and genetic diversity of three sympatric and closely related plover species in southwestern Madagascar: Kittlitz's plover ( Charadrius pecuarius), white-fronted plover ( C. marginatus), and Madagascar plover ( C. thoracicus). Bayesian clustering revealed strong population structure in the rare and endemic Madagascar plover, intermediate population structure in the white-fronted plover, and no detectable population structure in the geographically widespread Kittlitz's plover. In contrast, allelic richness and heterozygosity were highest for the Kittlitz's plover, intermediate for the white-fronted plover and lowest for the Madagascar plover. No evidence was found in support of the 'watershed mechanism' proposed to facilitate vicariant divergence of Madagascan lemurs and reptiles, which we attribute to the vagility of birds. However, we found a significant pattern of genetic isolation by distance among populations of the Madagascar plover, but not for the other two species. These findings suggest that interspecific variation in rarity, endemism, and dispersal propensity may influence genetic structure and diversity, even in highly vagile species. [ABSTRACT FROM AUTHOR]

The article discusses a research study about the influence of declining nest survival on the decline in the population of Snowy Plover at Great Salt Lake in Utah. Topics cited include the identification of nest survival, nesting substrate, the impact of predation, weather, and abandonment on daily nest survival rates, and the disadvantage of dikes as nesting habitat.

Many predators are also scavengers that feed on carrion and human refuse. Therefore, the availability of carrion can elevate the abundance or activity of facultative scavengers, amplifying predation pressure on prey. On Australian beaches, fishermen often discard fish carcasses that could attract facultative scavengers, both native, such as Australian ravens C orvus coronoides, and invasive, such as European red foxes V ulpes vulpes, and result in elevated rates of predation on wildlife. We tested whether the presence of fish carcasses increased the risk of depredation for nearby nests of beach-nesting birds by deploying artificial nests in 12 subsidized and 12 control patches, spaced 1 km apart, on a beach. We placed a fish carcass in each subsidized patch, but not at control patches. In each patch, we placed two artificial nests, which resembled red-capped plover C haradrius ruficapillus nests, 80 m apart and 40 m from carcasses at subsidized patches. Nest predators were identified from tracks and predator activity near subsidized and control nests was measured by counting tracks crossing a straight transect (220 m). The activity of a native predator, the Australian raven, was 17 times higher near (<80 m) nests with fish carcasses than nests without carcasses. After 72 h, 96% of nests near carcasses were depredated compared with 30% of nests without carcasses. Ravens were identified as the culprit for 80% of depredated nests. Although other predators were present in the study area, they did not depredate artificial nests in this experiment. Previous studies have highlighted the effects of permanent and/or large-scale food resources on scavenger abundance and impact. A key management implication of our study is that even small, sparsely distributed, temporally irregular food subsidies, provided by humans, can elevate the activity and predatory impacts of facultative scavengers. [ABSTRACT FROM AUTHOR]

The purpose of this article was to investigate the levels of metals, cadmium, lead, and zinc, in Western reef heron (Egrettagularis) (n = 15) in order to (1) examine the sex-related variation in trace metal accumulation and (2) determine the significant differences between the metal concentrations in the kidney, liver, and pectoral muscle. Bird samples were collected from throughout the Hara biosphere reserve of southern Iran, during November and December 2010 and the concentration of metals were measured using a Shimadzu AA 680 flame atomic absorption spectrophotometer. The overall cadmium, lead and zinc concentrations means were measured as 0.8 ± 0.1, 3.4 ± 1.1, and 29.4 ± 12.9 μg/g for kidney; 0.7 ± 0.1, 2.2 ± 0.5, and 65.9 ± 20.7 μg/g for liver; and 0.2 ± 0.1, 2.2 ± 0.7, and 17.6 ± 12.9 μg/g for pectoral muscle, respectively. The results showed that with the exception of cadmium in liver, there were no significant differences between males and females (t test, p > 0.05). In the contrast, the results indicated metal concentrations differed significantly in kidneys, livers, and pectoral muscles among tissues in Western reef heron (one-way analysis of variance, p < 0.001). [ABSTRACT FROM PUBLISHER]

Incubation is energetically demanding, but it is debated whether these demands constrain incubation-scheduling (i.e., the length, constancy, and timing of incubation bouts) in cases where both parents incubate. Using 2 methods, we experimentally reduced the energetic demands of incubation in the semipalmated sandpiper, a biparental shorebird breeding in the harsh conditions of the high Arctic. First, we decreased the demands of incubation for 1 parent only by exchanging 1 of the 4 eggs for an artificial egg that heated up when the focal bird incubated. Second, we reanalyzed the data from the only published experimental study that has explicitly tested energetic constraints on incubation-scheduling in a biparentally incubating species (Cresswell et al. 2003). In this experiment, the energetic demands of incubation were decreased for both parents by insulating the nest cup. We expected that the treated birds, in both experiments, would change the length of their incubation bouts, if biparental incubation-scheduling is energetically constrained. However, we found no evidence that heating or insulation of the nest affected the length of incubation bouts: the combined effect of both experiments was an increase in bout length of 3.6 min (95% CI: -33 to 40), which is equivalent to a 0.5% increase in the length of the average incubation bout. These results demonstrate that the observed biparental incubation-scheduling in semipalmated sandpipers is not primarily driven by energetic constraints and therefore by the state of the incubating bird, implying that we still do not understand the factors driving biparental incubation-scheduling. [ABSTRACT FROM AUTHOR]

The bush stone-curlew Burhinus grallarius is listed as 'Near threatened' on the IUCN Red List of Threatened Species. In NSW, bush stone-curlews are listed as 'Endangered' under the Threatened Species Conservation Act 1995. The present study focused on bush stone-curlew populations throughout the central coast of NSW and the aim of this study was to develop an inductive spatial model in Geographical Information System (GIS) of suitable bush stone-curlew habitat based on historical sightings and empirical data. To develop the models, micro-habitat data from 30 sites where bush stone-curlews have been recorded were combined with broad historical habitat maps between Gosford and Port Stephens. The habitat data and developed spatial models indicated that bush stonecurlew sightings are associated with trees dominated by Casuarina glauca and Syncarpia glomulifera. In terms of broad habitat classifications, bush stone-curlews are more likely to be sighted in wet sclerophyll forests (towards Gosford) and dry sclerophyll forests and saline wetlands (Port Stephens). The spatial model developed for this endangered bird will help direct conservation efforts to maintain and promote habitat in areas where urban development is rapidly increasing. [ABSTRACT FROM AUTHOR]

Weather conditions experienced by birds can influence their migration decision-making and strategy both within and across seasons. Additionally, decision-making during migration may influence subsequent fitness (reproductive success and/or survival). Examining the effects of fine-scale weather variables on individuals throughout the year could help identify stages of the annual cycle when species may be most affected by weather. In this study, we captured 24 black-bellied plovers (gray plovers; Pluvialis squatarola ) on nonbreeding areas along the western Gulf of Mexico coast and tracked their locations once every 2 h through their breeding season in the Alaskan and Canadian Arctic. We quantified migration strategies and weather conditions experienced by each individual throughout the nonbreeding, northward migration, and breeding seasons. We used a Bayesian hierarchical model which connected regressions linking weather with migration metrics, and migration metrics and breeding season weather with reproductive success. We found strong negative relationships between two migration metrics (migration duration and number of stopovers) and reproductive success, but no substantial relationships between breeding season weather variables and reproductive success. We found negative relationships between nonbreeding season temperature, migration temperature, and migration NDVI and both migration duration and number of stopovers, in addition to positive relationships between the number of stopovers and storms during migration, migration duration, and nonbreeding season precipitation. These results suggest that reproductive success is influenced by weather throughout the annual cycle and migration strategy is a key mechanism through which these effects operate. Our findings suggest that environmental factors throughout the year influence shorebird fitness, and, because black-bellied plovers are often associated with mixed-species flocks, many species likely experience similar constraints., (© 2022 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Invasive non-native species are one of the greatest drivers of the loss of biodiversity world-wide. Consequently, removing or controlling invasive predators should generally benefit vulnerable native species. However, especially on islands, where most mammalian predators are introduced, these predators may also prey on other invasive mammals. Removing only apex predators may lead to increases of meso-predators that may in turn increase predation pressure on native wildlife., We examined the benefits of a feral cat Felis catus control programme on nest survival of a critically endangered ground-nesting bird, the St Helena Plover Charadrius sanctaehelenae in two habitat types, harbouring c. 30% of the global population of this species. We monitored nest success and the activity of introduced mammals (cats, rabbits Oryctolagus cuniculus, rats Rattus rattus and Rattus norvegicus, and mice Mus musculus) over 2 years, before and after controlling feral cats., Live trapping removed 56 feral cats from our study areas. In the semi-desert, rabbit and mouse activity increased, but rat activity remained low after feral cat control. In pastures, rat and mouse activity increased after feral cat control, while rabbit activity remained constant., Nest survival of plovers increased more than threefold in the semi-desert, but increased only marginally in pastures. This difference may be due to an increase in rat activity and potentially rat predation following cat control in pastures, whereas no increase in rat activity was observed in the semi-desert., Synthesis and applications. Our study shows habitat-specific consequences of feral cat control on ground-nesting bird productivity after 1 year, probably mediated by differences in the availability of alternative prey. The results highlight the importance of experimental trials and a thorough understanding of the interactions between multiple invasive species before predator-control operations are implemented over larger scales. On islands with multiple invasive species, there may not be a simple generic approach to predator management (other than removing all invasive species simultaneously). [ABSTRACT FROM AUTHOR]

A principal goal of conservation efforts for threatened and endangered taxa is maintenance of genetic diversity. Modern and historic processes that limit population size can contribute to a loss of genetic variation that can reduce future adaptability of a species. Buff-breasted Sandpipers ( Calidris subruficollis) are a Neotropical migratory shorebird that experienced rapid, large-scale declines in population numbers (population bottleneck) due to intensive market hunting at the turn of the 20th century. Market hunting ended shortly after the passage of the Migratory Bird Treaty Act in 1918, but subsequent population losses have occurred due to continued anthropogenic disturbances throughout the species' migratory range. To assess the impact of population declines on the genetic variation of Buff-breasted Sandpipers, we surveyed two mitochondrial DNA (mtDNA) markers, the control region and cytochrome b, from 209 museum specimens collected between 1874 and 1983 and 460 modern samples collected between 1993 and 2009. Measures of mtDNA variation did not change significantly among individuals sampled before and after the ban on market hunting, nor among four temporal groups (Pre-Act, Early Post-Act, Late Post-Act, and Modern; trend analysis: χ = 0.171, P = 0.679). Similarly, we did not observe loss of common haplotypes, implying that there was no substantial reduction in unique matrilineal units during our 135-year study period. Using Bayesian Skyline reconstruction of temporal changes in effective population size of females ( N), we concluded that N has been stable for the past century. Results of resampling suggest that diversity estimators can be imprecise and we emphasize the importance of a well-rounded analytical approach to addressing conservation genetic hypotheses. Considering all of the evidence it appears that genetic variation and N were stable despite the pressures of market hunting early in the 20th century and habitat loss and degradation in the latter half of the 20th century. Conservation efforts should continue to focus on maintaining the population size of Buff-breasted Sandpipers to avoid reaching a threshold where genetic variability is lost. [ABSTRACT FROM AUTHOR]

The migration route of Red-necked Phalarope populations breeding on North Atlantic islands has been subject to considerable speculation. Geolocator tags were fitted to nine Red-necked Phalaropes breeding in northern Scotland to assess whether they migrated to Palaearctic or Nearctic wintering grounds. Of four birds known to return, two had retained their tags, of which one was recaptured. This male Phalarope left Shetland on 1 August 2012 and crossed the Atlantic Ocean to the Labrador Sea off eastern Canada in 6 days, then moved south to reach Florida during September, crossed the Gulf of Mexico into the Pacific Ocean and reached an area between the Galapagos Islands and the South American coast by mid- October, where it remained until the end of April, returning by a similar route until the tag battery failed as the bird was crossing the Atlantic Ocean. The total migration of 22 000 km is approximately 60% longer than the previously assumed route to the western part of the Arabian Sea, and this first evidence of migration of a European breeding bird to the Pacific Ocean also helps to indicate the possible migratory route of the large autumn movements of Red-necked Phalaropes down the east coast of North America. [ABSTRACT FROM AUTHOR]

Previous studies have documented advancement in clutch initiation dates (CIDs) in response to climate change, most notably for temperate-breeding passerines. Despite accelerated climate change in the Arctic, few studies have examined nest phenology shifts in arctic breeding species. We investigated whether CIDs have advanced for the most abundant breeding shorebird and passerine species at a long-term monitoring site in arctic Alaska. We pooled data from three additional nearby sites to determine the explanatory power of snow melt and ecological variables (predator abundance, green-up) on changes in breeding phenology. As predicted, all species (semipalmated sandpiper, Calidris pusilla, pectoral sandpiper, Calidris melanotos, red-necked phalarope, Phalaropus lobatus, red phalarope, Phalaropus fulicarius, Lapland longspur, Calcarius lapponicus) exhibited advanced CIDs ranging from 0.40 to 0.80 days/year over 9 years. Timing of snow melt was the most important variable in explaining clutch initiation advancement ('climate/snow hypothesis') for four of the five species, while green-up was a much less important explanatory factor. We found no evidence that high predator abundances led to earlier laying dates ('predator/re-nest hypothesis'). Our results support previous arctic studies in that climate change in the cryosphere will have a strong impact on nesting phenology although factors explaining changes in nest phenology are not necessarily uniform across the entire Arctic. Our results suggest some arctic-breeding shorebird and passerine species are altering their breeding phenology to initiate nesting earlier enabling them to, at least temporarily, avoid the negative consequences of a trophic mismatch. [ABSTRACT FROM AUTHOR]

Some ground-nesting birds adopt a mixed strategy of nesting in the open, or under cover (e.g. vegetation). This may represent a trade-off between thermally favourable nest sites (covered) and those that enable the early detection and avoidance of predators (open). This study examined whether such a trade-off exists for Red-capped Plover Charadrius ruficapillus, whose eggs are preyed upon principally by Little Raven Corvus mellori. For real and artificial nests, nest temperatures under cover (real, 25.9 ± 0.1°C; false, 16.2 ± 0.5°C) were cooler than those in the open (real, 26.8 ± 0.1°C; false, 17.4 ± 0.9°C). Covered nests had more visual obstructions than open nests (covered, 65.5% + 11.4%; open, 7.4% ± 2.8%) and a standardised measure of incubator escape distance, initiated by experimental human approaches, indicated incubators fled open nests at longer distances than for covered nests. Nests under cover showed a slightly (non-significant) higher probability of surviving one day (Daily Survival Rate [DSR] = 0.978) than those in the open (DSR = 0.950). For false nests containing model eggs, covered nests exhibited better survival to 10 days compared with open nests (20.4% vs. 4.7%). Thus, covered nests are associated with enhanced thermal environments and egg survival, but predators can approach the incubator more closely. Overall, the proposed trade-off between thermal and predation risks associated with nest sites appears to exist and explains the ongoing occurrence of nests in open and covered locations. [ABSTRACT FROM AUTHOR]

How breeding birds distribute in relation to landscape-scale habitat features has important implications for conservation because those features may constrain habitat suitability. Furthermore, knowledge of these associations can help build models to improve area-wide demographic estimates or to develop a sampling stratification for research and monitoring. This is particularly important for rare species that have uneven distributions across vast areas, such as the federally listed piping plover ( Charadrius melodus; hereafter plover). We examined how remotely-sensed landscape features influenced the distribution of breeding plover pairs among 2-km shoreline segments during 2006-2009 at Lake Sakakawea in North Dakota, USA. We found strong associations between remotely-sensed landscape features and plover abundance and distribution (R = 0.65). Plovers were nearly absent from segments with bluffs (>25 m elevation increase within 250 m of shoreline). Relative plover density (pairs/ha) was markedly greater on islands (4.84 ± 1.22 SE) than on mainlands (0.85 ± 0.17 SE). Pair numbers increased with abundance of nesting habitat (unvegetated-flat areas $${\hat{\beta }} = 0.28 \pm 0.08\,{\text{SE}}$$ ). On islands, pair numbers also increased with the relative proportion of the total area that was habitat ( $${\hat{\beta }} = 3.27 \, \pm \, 0.46\,{\text{SE}}$$ ). Our model could be adapted to estimate the breeding population of plovers or to make predictions that provide a basis for stratification and design of future surveys. Knowledge of landscape features, such as bluffs, that exclude use by birds refines habitat suitability and facilitates more accurate estimates of habitat and population abundance, by decreasing the size of the sampling universe. Furthermore, techniques demonstrated here are applicable to other vast areas where birds breed in sparse or uneven densities. [ABSTRACT FROM AUTHOR]

For species with precocial young, survival from hatching to fledging is a key factor influencing recruitment. Furthermore, growth rates of precocial chicks are an indicator of forage quality and habitat suitability of brood-rearing areas. We examined how growth and fledging rates of Piping Plover (Charadrius melodus) chicks were influenced by landscape features, such as hatchling density (hatchlings per hectare of remotely sensed habitat [H ha-1]), island vs. mainland, and wind fetch (exposure to waves) at 2-km segments (n = 15) of Lake Sakakawea, North Dakota, during 2007-2008. Hatchling growth was comparable with published estimates for other habitats. Models for fledging rate (fledged young per segment) assuming density dependence had more support (i = 96%) than those assuming density independence (wi = 4%). Density-dependent processes appeared to influence fledging rate only at densities >5 H ha1, which occurred in 19% of the segments we sampled. When areas with densities >5 FI ha-1 were excluded, density-dependence and density-independence models were equally supported (wi = 52% and 48%, respectively). Fledging rate declined as the wind fetch of a segment increased. Fledging rate on mainland shorelines was 4.3 times greater than that on islands. Previous work has indicated that plovers prefer islands for nesting, but our results suggest that this preference is not optimal and could lead to an ecological trap for chicks. While other researchers have found nesting-habitat requirements to be gravelly areas on exposed beaches without fine-grain substrates, our results suggest that chicks fledge at lower rates in these habitats. Thus, breeding plovers likely require complexes of these nesting habitats along with protected areas with fine, nutrient-rich substrate for foraging by hatchlings. [ABSTRACT FROM AUTHOR]

Stopover locations represent critical hábitat in the life cycle of migratory birds and the alteration of this hábitat can profoundly influence a population. American Golden-Plovers {Pluvialis dominica) migrate though the Midwestern United States each spring, where most natural hábitat has been converted to row crop agriculture. We investigated the stopover ecology of the golden-plover in the agricultural matrix of east-central Illinois and west-central Indiana between 2008 and 2012. We found that golden-plovers remained in the region for ~45 days and individuals spent on average 24 days in the area before departing to the northwest. During a period of peak migration, golden-plovers preferred fields with standing water and, to a lesser extent, soybean fields. Over the 45-day stopover duration, golden-plovers moved extensively (shown by a dynamic occupancy model and area used estimation), with some evidence for tilled fields becoming unoccupied at greater rates than untilled fields. The tendency to use fields with standing water and the movement of individuals from tilled fields suggests that food accessibility, rather than food abundance, is likely a critical factor associated with the prolonged stay, movement, and field type selection of golden-plovers. Food accessibility is important to the golden-plover because they undergo molt into breeding plumage in the region and must refuel for the next leg of their migration. The Midwest is a key stopover location for American Golden-Plovers and promoting foraging conditions by manipulating the drainage of agricultural fields, via the temporary blockage of drain tiles, should be a management focus. [ABSTRACT FROM AUTHOR]

Highlights: [•] We develop a Bayesian network to predict piping plover nest presence. [•] Nest predictions were linked to physical nesting habitat features. [•] Wide environmental ranges produced the best model performance. [•] All models were better at predicting nest presence than nest absence. [Copyright &y& Elsevier]

Highlights: [•] Remotely-sensed breeding habitat for a federally-listed species. [•] Habitat varied markedly among years (1986–2009) ranging from 9 to 5195ha. [•] Predicted habitat (ha) with water levels, modeled revegetation rate, and topography. [•] Predictive model could inform conservation through what-if scenarios. [•] Approach adaptable to other systems to improve habitat and population estimation. [Copyright &y& Elsevier]

Aim Although habitat suitability maps derived from species distribution models ( SDMs) are often assumed to highlight locations that can sustain healthy populations over time, the relationship between suitability scores and fitness parameters has rarely been tested thoroughly. Location Zackenberg Valley, north-east Greenland. Methods Using 14 years of data (1997-2010) representing three wader species (dunlin Calidris alpina, sanderling Calidris alba and ruddy turnstone Arenaria interpres), we tested the relationships between modelled suitability and fitness parameters at nesting locations. Results Among the three species examined, only the ruddy turnstone exhibited significant relationships between suitability and nest success, but over time rather than space. During years with extensive snow cover in the landscape, the nesting sites of ruddy turnstone occurred in different habitats than were typically used across years. Moreover, in years with extensive snow cover, the ruddy turnstone initiated nests later and suffered from higher egg predation rates. Main conclusion Our results suggest that SDMs derived from species occurrences that include years of low reproductive success may over-estimate the potential suitable habitat in the landscape. Whenever possible, variation in reproductive success should be considered when building models to inform species' response to environmental change. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Field Ornithology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ornitologia Colombiana is the property of Asociacion Colombiana de Ornitologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Although much of the Arctic Coastal Plain has remained undeveloped, oil and gas industries, new and expanding villages, as well as tourism are likely to increase in the near future. One potential effect of increased human development is increased anthropogenic waste and the need to dispose of this waste in landfills. We investigated potential indirect effects of the North Slope Borough landfill on breeding shorebirds by examining changes in environmental conditions (predator densities and timing of snow melt) and measures of shorebird reproduction (nest-initiation dates, nest density, nest survival, and return rates) in relation to construction and deposition of waste in the landfill. This study included one year of pre-construction data (2004), three years when landfill roads and fences were being constructed (2005-2007), and five years when waste was being deposited (2008-2012). We monitored 364 shorebird nests within a 36-ha plot (approximately half of which was inside the landfill and half outside). Construction of a fence around the landfill reduced snow levels inside the landfill, leading to earlier snow melt and likely to shorebirds initiating nests earlier. Densities of avian predators increased following waste deposition, but nest densities, nest survival, and return rates were generally greater inside the landfill than outside in all years after landfill construction. Our results indicate that fences placed around landfills and procedures to reduce attraction of predators to landfills can minimize indirect negative effects of landfill construction and operation and even favor species breeding in the area. [ABSTRACT FROM AUTHOR]

Wetland habitats in the Prairie Pothole Region of North America have been greatly reduced since European settlement, but the availability of managed wetlands has increased. The relative efficacy of these two habitats for meeting energetic demands of migrating shorebirds is unknown. To assess the relative suitability of stopover sites, we measured plasma metabolites and creatine kinase in Least Sandpipers (Calidris minutilla), Semipalmated Sandpipers (C. pusilla), and Pectoral Sandpipers (C. melanotos) at natural and managed wetland sites during fall migration in northeastern South Dakota and westcentral Minnesota. We used stepwise multiple regression to identify significant effectors of plasma metabolite levels, followed by analysis of covariance to compare metabolite values between birds in the two habitat types. Plasma metabolite levels generally did not differ significantly between birds in the two habitat types, with two exceptions. Plasma triglycerides of Pectoral Sandpipers were 2.6× higher at managed than at natural wetlands, suggesting higher rates of fattening at managed sites, but this was not supported by plasma glycerol levels, which did not differ significantly between birds in the two habitat types, or by body mass, which was greater for adult males in natural wetlands. Plasma creatine kinase levels of Least Sandpipers were 75% higher at managed than at natural wetlands, which suggests that repair of flight-induced muscle damage may be slower for this species at managed wetlands. The general absence of significant differences in plasma metabolites among shorebirds in the two wetland types suggests that natural and managed wetlands serve as similarly effective stopover habitat for fall-migrating shorebirds in the Prairie Pothole Region. [ABSTRACT FROM AUTHOR]

Estimates of seasonal mortality for long-distance migrant birds are extremely challenging to collect and consequently reports are scarce. Determining when and where mortality occurs within the annual cycle is important for an understanding of population dynamics and the evolutionary drivers of long-distance migration. We collected data on seasonal survival in a mark-recapture study of colour-marked Red Knots Calidris canutus canutus in their main wintering area at tropical Banc d'Arguin, Mauritania, West Africa. Our study population breeds 9,000 km to the northeast on Taymyr Peninsula, central northern Siberia. Our results show that annual apparent survival decreased from 0.87 ± 0.01 (SE) in 2002-2005 to 0.78 ± 0.02 in 2006-2009. During the 3-year time-window between 2006 and 2009, additional resightings just before migration and after return to the wintering grounds allowed us to partition the year into two periods: the non-breeding period on the Banc d'Arguin, and the migration and breeding period away from it. We estimated that, on the Banc d'Arguin, the 2-month apparent survival rate was 0.94 ± 0.01, whereas 2-month survival approached unity during the rest of year. Hence, most mortality occurred on the tropical wintering grounds. We review the possible physiological and ecological stressors involved and discuss the generality of these results. [ABSTRACT FROM AUTHOR]

The ability of birds to perceive, assess and appropriately respond to the presence of relatively novel threats is important to their survival. We hypothesized that the cognitive capacity of birds will influence their ability for accurate response to novelty. We used brain volume as a surrogate for cognitive capacity and postulated that larger brained birds would moderate their responses when presented with a benign, frequently occurring stimulus, such as a person, because they would habituate more readily. We conducted phylogenetic generalized least square regression to investigate the relationship between brain volume and flight initiation distance (FID; the distance to which a bird can be approached before initiating escape behaviour), while controlling for confounding factors including body size (body mass and wing length) and migration status. We compared seven different models using combinations of these parameters using Akaike's information criterion to determine the best approximating model(s) explaining FID. The two best-supported models included only wing length and only body mass with Akaike weights of 0.396 and 0.311 respectively. No model including brain volume had an Akaike weight greater than 0.083 and brain volume was poorly correlated with FID in models after controlling for body mass. Thus, brain volume does not appear to strongly relate to bravery among these shorebirds. [ABSTRACT FROM AUTHOR]

Range-wide monitoring of shorebirds (Aves: Charadriiformes) suggests that many species are declining. For most species, it is unknown whether distinct population units exist, which makes management and conservation difficult. One shorebird of conservation concern, the Buff-breasted Sandpiper (Tryngites subruflcollis), is a New World migrant that breeds at Arctic latitudes in North America and Russia and winters in southeastern South America. We conducted a molecular surveyof samples representing each of three migratory regions (breeding, migration, and wintering) using nine polymorphic microsatellite loci and 1.5 kb of highly variable mitochondrial DNA (mtDNA) from the cytochrome b gene and mtDNA control region. We analyzed contemporary population structure, demographic trends, and phylogeographic patterns. Overall, microsatellite and mtDNA analyses revealed that Buff-breasted Sandpipers are panmictic both regionally and at a global scale, with no signal of a recent genetic bottleneck. The mtDNA analyses revealed a pattern of haplotype diversity consistent with an expansion from a single refugium (Tajima's D: -2.27, P < 0.01; Fu's F$: -30.6, P < 0.0001), after the height of the Wisconsinan glaciation (8,400-45,000 years before present). Overall, our molecular analyses suggest that Buff-breasted Sandpipers should be treated as a single conservation unit, and management efforts for this species should focus on limiting future declines to ensure that genetic viability is maintained. [ABSTRACT FROM AUTHOR]

Within Europe, agri-environment schemes are the key delivery mechanism for biodiversity conservation outside protected areas. Schemes have a range of land management options designed to deliver outcomes for target habitats or species., Breeding waders form an important part of the biodiversity of upland grasslands, and in the UK, there are multiple land management options within agri-environment schemes designed to benefit waders. We assessed whether such options improve the suitability of breeding habitat and population dynamics for a declining wader, the lapwing Vanellus vanellus., The suitability of nesting and chick-rearing habitat was better on land with agri-environment scheme management, and breeding densities and productivity increased with habitat suitability., The lapwing populations declined during this study, and trends did not differ between agri-environment and non-agri-environment scheme land. Productivity was below that required for population stability, although there was evidence of higher productivity on agri-environment scheme land in later years., Agri-environment management consisted of multiple land management options that varied in delivery of suitable habitat, breeding densities and success. The best management options were all in England on land benefiting from specific management advice or with rough grazing and grazed pasture agri-environment scheme options., Synthesis and applications. Despite considerable investment and positive effects of agri-environment schemes on habitat quality, populations of lapwing in the UK uplands have declined because of inadequate productivity. For species with complex requirements, populations are only likely to increase when all of these requirements are provided. Appropriately targeted habitat management, delivered through agri-environment schemes, can play an important role in improving habitat quality and increasing landscape diversity. However, when populations are limited by something other than habitat quality, for example, predation, then habitat management alone is unlikely to recover populations. Increasing evidence suggests that predation impacts are also likely to be important for ground-nesting species such as lapwing. Predator management may therefore need to be integrated with habitat measures where predation is limiting breeding success and population recovery. [ABSTRACT FROM AUTHOR]

Abstract: Sum-PBDEs concentrations in shorebirds and Anatidae ducks muscles from Chongming Dongtan National Nature Reserve ranged from 21–324 to 14–159ngg−1 lw, respectively. PBDEs were detected in muscles of all the studied species. Compared with flyways around the world, migratory waterbirds on the East Asian–Australasian flyway exhibited lower PBDEs burdens than those reported on Black Sea-Mediterranean flyway in Europe and Pacific, Atlantic, Mississippi flyway in North America. Residential Eurasian tree sparrow samples indicated few PBDE products were used in Chongming Island developed in the idea of world famous eco-island. There was no significant difference in PBDEs concentrations between shorebirds and ducks. However, PBDEs composition varied between them. BDE 209 (29–44%) contributed to sum-PBDEs more than BDE 47 (17–19%) in muscles of ducks, while BDE 47 was the predominant congener in shorebirds contributing 32–48%. Stable nitrogen and carbon isotopes and stomach content analysis indicated shorebirds and ducks had the same dietary composition, but showed different preference to bivalves, gastropods and crustaceans for shorebirds and aquatic plant material for ducks. Migratory species had inherent migratory routes and thus had exposure to PBDEs during their stay in breeding grounds, stopover sites and wintering grounds with high use of different commercial PBDE mixtures. Higher percentage of BDE 209 in ducks than shorebirds suggested that breeding ranges and wintering grounds of ducks comprise wetlands in inland and coastal China and Korea where decaBDEs pollution was serious in Asian-Pacific region. Our findings reveal the influence of migratory behavior on PBDEs distribution in migratory waterbirds. [Copyright &y& Elsevier]

River flow management and modification is a global issue, and its effects on river-dependent organisms are pervasive. Flow modification can directly affect avian species through mortality or habitat loss, but less is known about indirect and sublethal effects of flow modification on reproductive output in these species. Young birds are more vulnerable to predation between hatching and fledging than after flight is achieved, but tradeoffs must be made to balance growth and survival. Predation pressure appears to be a significant factor affecting the time to fledging in altricial birds, but less is known about this threat for precocial birds. Birds reaching fledging earlier should have greater rates of survival to migration because their predator escape repertoire includes flight at an earlier age. We evaluated the effect of varying outflows from the Gavins Point Dam on the growth, age at fledging, and survival of piping plover ( Charadrius melodus) chicks on the Missouri River (2006-2009). The study was characterized by 2 relatively high flow years (2006 and 2009) and 2 relatively low flow years (2007 and 2008). We used success rate in recapturing chicks in capture-mark-recapture models as an index for fledging. We attempted to recapture all chicks ( n = 1,099) by hand every 3-4 days throughout the season to acquire morphological measurements. Models indicated that as flows from the dam increased, age at fledging increased. We also found that increasing flows were associated with decreasing daily survival rates ( βflow = −2.401, 95% CI: −4.351 to −0.452). Flow was also negatively related to chick mass gain, but we found less evidence for an effect on wing-chord length. Increased flows covered wet-substrate foraging habitat, and likely affected plover reproductive output directly through chick survival and indirectly through decreased growth and increased fledging times. © The Wildlife Society, 2013 [ABSTRACT FROM AUTHOR]

The propensity to replace a clutch is a complex component of avian reproduction and poorly understood. We experimentally removed clutches from an Arctic-breeding shorebird, the Dunlin (Calidris alpina arcticola), during early and late stages of incubation to investigate replacement clutch rates, renesting interval, and mate and site fidelity between nesting attempts. In contrast to other Arctic studies, we documented renesting by radiotracking individuals to find replacement clutches. We also examined clutch size and mean egg volume to document changes in individual females' investment in initial and replacement clutches. Finally, we examined the influence of adult body mass, clutch volume, dates of clutch initiation and nest loss, and year on the propensity to renest. We found high (82-95%) and moderate (35-50%) rates of renesting for early and late incubation treatments. Renesting intervals averaged 4.7-6.8 days and were not different for clutches removed early or late in incubation. Most pairs remained together for renesting attempts. Larger females were more likely to replace a clutch; female body mass was the most important parameter predicting propensity to renest. Clutches lost later in the season were less likely to be replaced. We present evidence that renesting is more common in Arctic-breeding shorebirds than was previously thought, and suggest that renesting is constrained by energetic and temporal factors as well as mate availability. Obtaining rates of renesting in species breeding at different latitudes will help determine when this behavior is likely to occur; such information is necessary for demographic models that include individual and population-level fecundity estimates. [ABSTRACT FROM AUTHOR]

Migratory movements in air or water are strongly affected by wind and ocean currents and an animal which does not compensate for lateral flow will be drifted from its intended direction of movement. We investigated whether arctic shorebirds during autumn migration in the region of South Sweden and the southern Baltic Sea compensate for wind drift or allow themselves to be drifted when approaching a known goal area under different circumstances (over sea, over land, at low and high altitude) using two different approaches, visual telescope observations and tracking radar. The shorebirds showed clearly different responses to crosswinds along this short section (<200 km) of the migratory journey, from almost full drift when departing over the sea, followed by partial drift and almost full compensation at higher altitudes over land during later stages. Our study demonstrates that shorebirds are also remarkably variable in their response to crosswinds during short sections of their migratory journey. The recorded initial drift close to departure is probably not adaptive but rather a result of constraints in the capacity of the birds to compensate in some situations, e.g. in low-altitude climbing flight over the sea. We found no difference in orientation response to wind between adult and juvenile birds. This study indicates, in addition to adaptive orientation responses to wind, the importance of the non-adaptive wind drift that contributes to increasing the variability of drift/compensation behaviour between places that are separated by only short distances, depending on the local topographic and environmental conditions. [ABSTRACT FROM AUTHOR]

The major histocompatibility complex (MHC) includes highly polymorphic gene families encoding proteins crucial to the vertebrate acquired immune system. Classical MHC class I (MHCI) genes code for molecules expressed on the surfaces of most nucleated cells and are associated with defense against intracellular pathogens, such as viruses. These genes have been studied in a few wild bird species, but have not been studied in long-distance migrating shorebirds. Red Knots Calidris canutus are medium-sized, monogamous sandpipers with migratory routes that span the globe. Understanding how such long-distance migrants protect themselves from disease has gained new relevance since the emergence of avian-borne diseases, including intracellular pathogens recognized by MHCI molecules, such as avian influenza. In this study, we characterized MHCI genes in knots and found 36 alleles in eight individuals and evidence for six putatively functional and expressed MHCI genes in a single bird. We also found evidence for recombination and for positive selection at putative peptide binding sites in exons 2 and 3. These results suggest surprisingly high MHC diversity in knots, given their demographic history. This may be a result of selection from diverse pathogens encountered by shorebirds throughout their annual migrations. [ABSTRACT FROM AUTHOR]

1. The immediate impacts of nutrient inputs on aquatic systems are well documented, but the ways in which resource pulses affect the wider food web of water-associated vertebrates remain obscure. 2. We monitored the wading bird community of Barberspan, a natural freshwater lake and Ramsar wetland in South Africa, before, during and after the addition of a pulse of nutrients in the form of a sewage overspill from an upstream processing facility. We counted waders at 13 points around the lake over 3 years, every 2 months from March 2007 to March 2010, and sampled water quality during all counting periods from January 2008 to January 2010. 3. We used our data to test the hypothesis that wading birds that forage directly at lower trophic levels and/or on prey populations that have fast turnover rates, such as those of phytoplankton and invertebrates, will be more heavily influenced by nutrient addition than birds that forage on species with lower turnover rates and/or at higher trophic levels (such as frogs and fish). 4. During the sampling period Barberspan experienced a significant, nutrient-driven decline and subsequent recovery in dissolved oxygen and pH. This trend was mirrored by significant changes in the wading bird community. Partial Mantel tests and Canonical Correspondence Analysis (CCA) showed that the nutrient pulse had marked short-term, negative impacts on both the diversity and the abundance of medium-sized, shoreline foragers such as scolopacids (e.g. sandpipers). 5. Our analysis supports the proposal that both food-web position and the turnover rate of the prey population are strong influences on ecological responses to resource pulses. Analysis of time series of principal components that describe community composition suggested that recovery of the prey base was rapid and that the bird community was able to respond via immigration. These results must, of course, be considered provisional in the absence of replicated experimental data. 6. More generally, we interpret our results as suggesting that two different mechanisms act in different directions to determine the sensitivity of secondary and tertiary consumers to changes in their prey. First, for 'earlier' consumers (i.e. that forage lower in the food web), there are (on average) fewer generalist consumers and fewer stored nutrients in the intervening trophic levels. This increases the sensitivity of earlier consumer populations to changes in the composition of the primary consumer community. Second, the dynamics of prey populations lower in the food web tend to be faster, making recovery faster and serving to decrease the sensitivity of earlier consumers to perturbations. These dynamics may obscure the impacts of nutrient pulses in cases where additional analysis of system trajectories is not undertaken. [ABSTRACT FROM AUTHOR]

Please cite this paper as: Hall et al. (2012) Avian influenza in shorebirds: experimental infection of ruddy turnstones ( Arenaria interpres) with avian influenza virus. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750-2659.2012.00358.x. Background Low pathogenic avian influenza viruses (LPAIV) have been reported in shorebirds, especially at Delaware Bay, USA, during spring migration. However, data on patterns of virus excretion, minimal infectious doses, and clinical outcome are lacking. The ruddy turnstone ( Arenaria interpres) is the shorebird species with the highest prevalence of influenza virus at Delaware Bay. Objectives The primary objective of this study was to experimentally assess the patterns of influenza virus excretion, minimal infectious doses, and clinical outcome in ruddy turnstones. Methods We experimentally challenged ruddy turnstones using a common LPAIV shorebird isolate, an LPAIV waterfowl isolate, or a highly pathogenic H5N1 avian influenza virus. Cloacal and oral swabs and sera were analyzed from each bird. Results Most ruddy turnstones had pre-existing antibodies to avian influenza virus, and many were infected at the time of capture. The infectious doses for each challenge virus were similar (103·6-104·16 EID50), regardless of exposure history. All infected birds excreted similar amounts of virus and showed no clinical signs of disease or mortality. Influenza A-specific antibodies remained detectable for at least 2 months after inoculation. Conclusions These results provide a reference for interpretation of surveillance data, modeling, and predicting the risks of avian influenza transmission and movement in these important hosts. [ABSTRACT FROM AUTHOR]