Hematocrits were measured in Common Terns (Sterna hirundo) (n = 75) that were exposed to oil from a spill in Buzzards Bay, Massachusetts, USA, in 2003, and that laid eggs 17–39 days following the spill. Comparative data were obtained in three pre- and two post-spill years and from three unoiled reference sites. In non-spill years, annual means of hematocrit varied in parallel with breeding performance. Hematocrits were lower (mean 45.3, n = 75) and more variable in the oil spill year than in non-spill years, and 20% of birds sampled were anemic (hematocrit < 41.7). However, hematocrits were almost as low (mean 46.4, n = 44) in 2002, a year with naturally adverse conditions. In 2002, hematocrits and body-masses were depressed following two storms and recovered in parallel following the storms; hematocrits were positively correlated with body-mass and ambient temperature and negatively correlated with wind speed. In contrast, in 2003 hematocrits were negatively correlated with body-mass and temperature and positively correlated with wind speed. Hematocrits were very low (mean 39.8, n = 15) when birds were first sampled 20–23 days after the spill and recovered toward normal levels by day 39 (mean 49.4, n = 14). Reduced hematocrits can be a useful indicator of sublethal oil intoxication, especially in females, provided that they are not associated with low body-masses or adverse weather. Measuring hematocrits could be useful for rapid screening of populations sublethally exposed to oil.

The Ibisbill (Ibidorhyncha struthersii) is a rare shorebird uniquely adapted to high-altitude river rapids. Ibisbill has received little study as a result of its isolation and the inaccessibility of its habitat. The habitat utilization, time budgets and daily rhythm of Ibisbill were studied in the southwestern part of Sichuan Province, China, in July to August 2008 and January to February 2010. A total of 55 Ibisbills were recorded in summer and 87 in winter. Encounter rates and group size were similar in summer and winter, but habitat selection differed. In summer, most Ibisbills chose central islands in rivers that had many large stones offering opportunities for both camouflage and physical concealment, and riverside pasture covered by weedy growth with abundant insects making them suitable for foraging. In winter, when water levels are low and many stony beaches are exposed, Ibisbills were more often encountered on riverbanks. Foraging (48.9%) and resting (32.3%) were the most commonly observed behaviors, and the time that Ibisbills spent on foraging (t₁₉ = -4.0, P = 0.001) in winter was significantly higher than in summer. In winter, Ibisbills spent less time engaged in locomotion (t₁₉ = 5.1, P = 0.001) and resting (t₁₉ = -2.8, P = 0.012). Alertness increased toward sunset in summer but not in winter.

During winter, molluscivorous sea ducks often form high density feeding flocks in association with patchily distributed prey, although few studies have documented the substrate and prey characteristics where sea ducks (tribe: Mergini) aggregate and thus what constitutes high-value sea duck foraging habitat. Sea duck surveys were conducted and benthic grab samples collected at sites with different benthic substrate characteristics to compare macroinvertebrate community assemblages in relation to densities of three species of sea ducks: (Surf (Melanitta peispicillata), Black (M. americana), and White-winged (M. fusca) scoters (hereafter “oscoters” when combined) during winter (2010–2011) in Narragansett Bay, Rhode Island, an urbanized estuary in the Northwest Atlantic. Overall, the highest densities of scoters (104 ± 17 per 0.5 km²) were found over sand substrates with homogeneous assemblages of infaunal prey. Significantly lower densities of scoters (21 ± 4 per 0.5 km²) were associated with mixed sand-gravel-mud substrates that supported epifaunal assemblages and patchily distributed infauna. Mean energy densities (kcal/g) were higher among infaunal (0.64–4.49) vs. epifaunal (0.17–0.53) prey. Overall biomass (g/m²) of polychaetes was higher in mixed substrates, and biomass of infaunal bivalves did not significantly differ among habitat type. However, infaunal prey may have been less accessible to scoters at sites with mixed substrates due to a barrier effect created by high-densities of epifauna with low energetic value. Thus, sand-substrate sites supporting infaunal benthic communities may provide high-quality feeding habitat for scoters wintering in the Northwest Atlantic. Understanding the influences of benthic habitat characteristics and macroinvertebrate prey assemblages on distribution of feeding scoters is particularly important for managing sea ducks in areas with increasing anthropogenic development in the coastal zone.

Nest failure has often been identified as a factor affecting American Oystercatcher (Haematopus palliatus) survivorship. To examine causes of nest failure, small digital cameras were deployed between 6 April and 15 July 2005 on American Oystercatcher nests on Fisherman Island National Wildlife Refuge located in Northampton County, Virginia. Twenty-five attempts, representing 22 different pairs, were recorded resulting in 7,570 hr of video footage. Nest survivorship was 44% (n = 11). High tide events associated with coastal storms were the largest source of nest loss (24%, n = 6), followed by predation on eggs (16%, n = 4). Nest abandonment, unknown factors, and infertile eggs accounted for the remaining 16% (n = 4) of nests. The main predator was Fish Crows (Corvus ossifragus). While American Oystercatchers were incubating, 211 instances were recorded where individuals of 22 species entered the field of view of video cameras. The most common species entering included Boat-tailed Grackle (Oidscalus major) (22.7%), white-tailed deer (Odocoileus virginianus) (11.4%), Brown Pelican (Pelecanus occidentalis) (10.9%), Willet (Tringa semipalmata) (9.0%), and ghost crab (Ocypode quadrata) (7.1%). A wide range of responses to intruders from no reaction to permanent nest abandonment were displayed by incubating American Oystercatchers. The majority (65.9%, n = 139) of encounters were met with no reaction followed by fleeing the nest area (17.5%, n = 37), chasing the intruder (8.5%, n = 18), piping (7.6%, n = 16), and abandoning the nest (< 1.0%, n = 1). All predation events occurred when American Oystercatchers left nests unattended.

Semipalmated Sandpipers (Calidris pusilla) are among the most common North American shorebirds. Breeding in Arctic North America, this species displays regional differences in migratory pathways and possesses longitudinal bill length variation. Previous investigations suggested that genetic structure may occur within Semipalmated Sandpipers and that three subspecies corresponding to western, central, and eastern breeding groups exist. In this study, mitochondrial control region sequences and nuclear microsatellite loci were used to analyze DNA of birds (microsatellites: n = 120; mtDNA: n = 114) sampled from seven North American locations. Analyses designed to quantify genetic structure and diversity patterns, evaluate genetic evidence for population size changes, and determine if genetic data support the existence of Semipalmated Sandpiper subspecies were performed. Genetic structure based only on the mtDNA data was observed, whereas the microsatellite loci provided no evidence of genetic differentiation. Differentiation among locations and regions reflected allele frequency differences rather than separate phylogenetic groups, and similar levels of genetic diversity were noted. Combined, the two data sets provided no evidence to support the existence of subspecies and were not useful for determining migratory connectivity between breeding sites and wintering grounds. Birds from western and central groups displayed signatures of population expansions, whereas the eastern group was more consistent with a stable overall population. Results of this analysis suggest that the eastern group was the source of individuals that colonized the central and western regions currently utilized by Semipalmated Sandpipers.

Curbing the declining trends of King Rails (Rallus elegans) that occupy freshwater emergent marshes requires an understanding of their ecology and response to management practices. King Rails were surveyed during the breeding season (March-June) at Back Bay and Mackay Island National Wildlife Refuges, Virginia and North Carolina, in 2009 and 2010. Twenty-two plots were surveyed in 2009 and 41 in 2010. Annual occupancy estimates were based on pooled data encompassing both refuges. In 2010, occupancy and abundance of King Rails were also estimated for each refuge and assessed with respect to fire management. Plots in 2010 were classified as recently burned (0–1 years-since-burn [YSB]) or ≥ 2 YSB. Occupancy probability was similar between 2009 (0.68 ± 0.14) and 2010 (0.62 ± 0.08). In 2010, occupancy probability was higher at Mackay Island (0.95 ± 0.06) than Back Bay (0.69 ± 0.13). Mean plot abundance (Mackay Island = 1.47 ± 0.38; Back Bay = 0.66 ± 0.22) was also higher. The probability of occupying 0–1 YSB plots was higher at both refuges (Mackay Island = 0.95 ± 0.06; Back Bay = 0.72 ± 0.20) when compared to ≥ 2 YSB plots (Mackay Island = 0.69 ± 0.13; Back Bay = 0.25 ± 0.12). Location strongly influenced occupancy of King Rails. It is plausible that the marsh composition (natural vs. created) accounted for the observed differences in occupancy. Natural marshes may provide higher quality habitat (e.g., resource availability) for King Rails than created marshes.

Previous theory to explain pairing behavior in waterfowl suggested that timing of pairing was constrained by costs to males of being paired and assumed that males incur most of the cost of defense after a pair bond is formed. An alternative hypothesis predicts that male and female partners will mutually defend their pair bond and that an individual will assume a greater share of defense when paired to a relatively high than low quality partner. Behavior of wintering Harlequin Duck (Histrionicus histrionicus) pairs was consistent with the latter hypothesis. Females and males shared equally in pair-bond defense in new pairs involving young females, while males assumed a greater share of defense when paired to an older female. Overall, males performed more aggressive displays in defense of the pair bond than females, but displays by females were more frequently of higher intensity than those of their mate. The relative share of pair-bond defense also varied between females and males depending on the target of the aggressive display. In some pairs, females performed virtually all defensive displays and bore the primary cost of pair-bond defense. Even when sex ratios are male-biased, differences in male quality probably make females willing to protect a pair bond with a high-quality male. Mutual mate choice and shared defense of a pair bond indicated that “pair-bond defense” would be a more appropriate label than “mate-defense” for the mating system of Harlequin Ducks and likely most monogamous avian species.

The Yellow Rail (Coturnicops noveboracensis) is a focal species of concern associated with shallowly flooded emergent wetlands, most commonly sedge (Carex spp.) meadows. Their populations are believed to be limited by loss or degradation of wetland habitat due to drainage, altered hydrology, and fire suppression, factors that have often resulted in encroachment of shrubs into sedge meadows and change in vegetative cover. Nocturnal call-playback surveys for Yellow Rails were conducted over 3 years at Seney National Wildlife Refuge in the Upper Peninsula of Michigan. Effects of habitat structure and landscape variables on the probability of use by Yellow Rails were assessed at two scales, representing a range of home range sizes, using generalized linear mixed models. At the 163-m (8-ha) scale, year with quadratic models of maximum and mean water depths best explained the data. At the 300-m (28-ha) scale, the best model contained year and time since last fire (≤ 1, 2–5, and > 10 years). The probability of use by Yellow Rails was 0.285 ± 0.132 (SE) for points burned 2–5 years ago, 0.253 ± 0.097 for points burned ≤ 1 year ago, and 0.028 ± 0.019 for points burned > 10 years ago. Habitat differences relative to fire history and comparisons between sites with and without Yellow Rails indicated that Yellow Rails used areas with the deepest litter and highest ground cover, and relatively low shrub cover and heights, as well as landscapes having greater sedge-grass cover and less lowland woody or upland cover types. Burning every 2–5 years appears to provide the litter, ground-level cover, and woody conditions attractive to Yellow Rails. Managers seeking to restore and sustain these wetland systems would benefit from further investigations into how flooding and fire create habitat conditions attractive to breeding Yellow Rails.

Male-biased collision mortality of Whooping Cranes (Grus americana) in Florida may be associated with the tendency of males to lead flocks. The sex of Whooping Cranes was recorded for individuals leading flocks while flying and walking (n = 255). Males were more likely to lead than females both while walking and especially when flying. These observations support anecdotal reports that males tend to lead flocks. This flock behavior may partly explain male-biased mortality from collisions observed in Florida. Collision with power lines is the greatest known source of mortality for fledged Whooping Cranes. Our findings have implications for reintroductions and for the single existing self-sustaining population, which numbers > 250 individuals.

Snowy Plovers (Charadrius nivosus) have recently expanded their breeding range into the northern Great Plains. We studied the nest success and survival of Snowy Plovers nesting on the Missouri River between Nebraska and South Dakota from 2008–2011 by monitoring nests every 2–3 days and banding adults and chicks. We used the logistic exposure method to estimate nest success and capture-recapture models in Program MARK to estimate adult and chick survival. Snowy Plover nests had a daily survival rate of 0.978 ± 0.008, and annual adult apparent survival rate was 0.588 ± 0.119. In addition, we estimated that 0.63 ± 0.12 of Snowy Plover chicks survived to fledging (30 days) during our study. The results for Snowy Plovers were similar to results for Piping Plovers (Charadrius melodus) breeding in the same area, and the demographic rates in this study were similar to those reported from established portions of the species' range. Recent breeding range expansion may be due to spring flooding on established breeding grounds coupled with the drying of lakes and reservoirs in the northern Great Plains. Continued monitoring of breeding populations in this region should determine if expansion of the breeding area described in this study will persist, offering a rare opportunity to learn about population dynamics at the forefront of a species' range expansion.

In late fall and early winter > 2,000 Common Coots (Fulica atra) may gather on the small, shallow Lake Krankesjön in southern Sweden, where they dive for submerged plants. Casual observations indicated that intraspecific kleptoparasitism was common throughout these flocks. Kleptoparasitic attacks mostly occurred shortly after a Common Coot surfaced with food and before it had ingested much of it. Attacked birds rarely resisted, and kleptoparasitic individuals had a success rate of 85% (n = 290), including cases when the victim managed to keep part of the food. Kleptoparasitic Common Coots used a mixed strategy, alternating between parasitism and self-feeding.

Despite being listed as endangered, substantial morphological and behavioral variation exists within Black-capped Petrel (Pterodroma hasitata) populations. To examine the population genetic structure of the Black-capped Petrel, we amplified Cytochrome Oxidase 1 sequences from museum specimens collected during 1970–1980 off the coast of North Carolina, USA. These sequences revealed a 1.2% fixed genetic difference between dark and light morphs. Individuals with intermediate plumage all grouped phylogenetically with the light morph. Combined with significant differences in body size and phenology, our genetic results suggest breeding isolation of the dark and light morphs. Consistent with other Pterodroma species, our results imply that the Black-capped Petrel may comprise two distinct, reproductively isolated taxa. Further knowledge about the genetic identity of birds at specific nesting colonies will be valuable for geographic delineation of populations.

In a study of adult Common Eider (Somateria mollissima) females in northeastern England, the annual mortality rate increased by 1 percentage point every 4 years and doubled over the study period (1962–1995). All age classes of adult females experienced years of low mortality, but in years when the overall mortality was high, the oldest age groups suffered three times the mortality rate incurred by the younger females. Over 58% (n = 95) of all deaths of adult females each year occurred in a 60-day period starting in late May, just after the majority had hatched their eggs. Some of this mortality could be linked to the failure to build up large enough food reserves to meet both the costs of producing the eggs and then the stress of starving during the 26-day incubation period. However, this “capital” breeding strategy and variations in the availability of food in the period before laying did not totally explained the large year-to-year fluctuations in mortality, which varied by up to 33% between consecutive years; it also did not explain the variation in age-related deaths. The causes of variations in the mortality rates of Common Eiders may be related to compromised immunity developed during incubation, increasing the risk of death from viruses and helminth parasite infections.

The absence of juvenile sexual dimorphism in birds often impedes sex determination using external morphology. We examined sex ratio variation in Scopoli's Shearwater (Calonectris diomedea) fledglings (n = 135) on a Strofades island (southern Ionian Sea) between 2007 and 2011. We determined sex by using a polymerase chain reaction-based methodology on blood samples. The molecular technique revealed a slightly male-biased sex ratio (52.6% ) during the five consecutive breeding seasons. In addition, morphological analysis using six morphometric variables (bill length, bill width, nalospi, bill-head length, head length, tarsus length) and body weight indicated that males were significantly larger than females for all the tested variables. The combined use of those variables correctly classified 81.2% of known-sex fledglings, and the stepwise discriminant analysis pointed out that bill length was the most discriminating variable followed by bill depth, head length, and body weight.