Maternally derived hormones are known to influence the growth and development of offspring. The differential deposition of these maternally derived hormones into egg yolk is one way by which females can alter their chicks' growth or survival. Yolk constituents, especially testosterone, have been described for a wide variety of species. However, few studies have focused on multiple maternally derived hormones regulated by independent axes in the endocrine system, and those studies that have, mainly focus on corticosterone and testosterone. In this study, within and among female variation in testosterone and triiodothyronine concentrations in egg yolks were measured in three free-living Franklin's Gull (Leucophaeus pipixcan) populations. Testosterone (T), but not triiodothyronine (T3), concentrations increase within a female's clutch such that eggs laid later in the clutch have increasingly higher concentrations (from a mean of 1.97 log pg T/mg yolk for the first egg to 2.98 log pg T/mg yolk for the third egg compared to a mean of 0.14 log pg T3/mg yolk for the first egg to 0.31 log pg T3/mg yolk for the third egg). Both testosterone and triiodothyronine concentrations increase among females across the breeding season such that eggs laid later in the season have significantly higher hormone concentrations (mean of 2.37 log pg T/mg yolk and mean of -0.03 log pg T3/mg yolk) than eggs laid early in the season (mean of 1.95 log pg T/mg yolk and mean of -0.17 log pg T3/mg yolk).

The Black-necked Stilt (Himantopus mexicanus) is a migratory shorebird of temperate and tropical America. Declining wetland quality and associated declines in hydrological integrity may contribute to widespread habitat loss for stilts nesting on the upper Texas Gulf of Mexico coast of the USA, as both fresh and brackish marshes are converting to open water and saline marsh. Nests (n = 356) were monitored in three wetland types on the upper Texas coast from 21 April-30 June 2011-2012. Of these 356 nests, 151 were located in managed freshwater wetlands (16 in 2011 and 135 in 2012), 128 were located in managed intermediate wetlands (75 in 2011 and 53 in 2012), and 77 were located in rice fields (all in 2012). Collectively, nest success was 0.2% (0 in rice fields and as high as 4.3% in freshwater wetlands in 2012), among the lowest ever reported for the species. The most frequent cause of nest failure was predation by mammalian and avian predators (∼50%). Daily nest survival rate was positively related to mudflat nesting substrates and negatively related to colony size, rice field, and brackish coastal wetland habitats. Future efforts to minimize edge effects in managed wetlands may prove valuable to improve nest success of stilts and other species that nest in similar wetland types.

Piping Plovers (Charadrius melodus) and American Oystercatchers (Haematopus palliatus) are shorebird species of conservation concern that breed sympatrically along the U.S. Atlantic coast, facing substantial anthropogenic habitat loss and disturbance. Interspecific aggression has been increasingly observed in overlapping habitat, potentially resulting in diverting time and energy that would be available for breeding activities. Because nests are camouflaged against the substrate, nest site habitat is important to fitness. Understanding habitat selection disparities could inform management of both species while ameliorating agonistic interactions. Nest sites in New Jersey were compared with paired random sites based on median proportions of substrate covered by rock, shell, wrack, plant, and other items (including peat and plastic litter). Both American Oystercatchers (n = 37 nests) and Piping Plovers (n = 42 nests) selected certain substrate features in amounts disproportionate to their availability, and interspecific differences were present. For American Oystercatchers, wrack constituted 17.7% of the substrate at nest sites versus 2.0% at paired sites. Piping Plover nest sites had greater proportions of shells, and medium fragments (2-64 mm) alone represented 18.9% of nest substrate versus 6.3% at paired sites. Results indicate that substrate management may be effective in creating ecological separation between these species.

Diet of the Brandt's Cormorant (Phalacrocorax penicillatus) breeding population on Alcatraz Island, California, USA was determined for 2014-2016 using two sampling methods. Regurgitated pellets and complete nests were collected, once all chicks had left colonies, to reduce disturbance to nesting birds. Results identified 25 prey taxa including 23 teleost fishes and two cephalopods. Diet was dominated by northern anchovy (Engraulis mordax) and speckled sanddab (Citharichthys stigmaeus), with plainfin midshipman (Porichthys notatus), sole spp. (Pleuronectidae), and sculpin spp. (Cottidae) rounding out the top five abundant species. Comparison of diet by sample type yielded similar results in terms of prey species composition, but total diet differed between the two samples due to rare prey items being more prevalent in nest samples. Determining cormorant diet using a combination of pellet and nest samples is a novel approach with the potential to provide a better representation of prey consumed during the full breeding period (up to 6 months for cormorants), and similar methods may be informative for other seabirds that produce pellets. In contrast, diet determined from pellets alone may only represent a short time period just prior to collection, as pellets are often blown away by strong winds or disintegrate through trampling and/or exposure to the elements in open seabird breeding colonies.

Winter conditions impose hardships on waterfowl, impacting how they apportion energy and time. Human disturbances may affect this energetic balance, influence lipid reserves, and potentially survival. Objectives of this study were to determine effects of environmental and anthropogenic factors on energetic expenditure (kcal/day) of Northern Pintails (Anas acuta) in behaviors commonly associated with a disturbance response (alert, locomotion, and flight) during winter 2008-2009 and 2009-2010 at Bosque del Apache National Wildlife Refuge in central New Mexico, USA. The refuge is a frequently visited ecotourism destination with over 170,000 visitors each winter. Thermoregulatory cost, time-of-winter, amount of natural and anthropogenic disturbances, and forage availability were examined to determine their influence on pintail energetic response (e.g., flight, locomotion, alert behavior). Average number of pintails ranged from 7,524-15,769. Using Akaike Information Criteria, the top-ranked model indicated that increased thermoregulatory cost, and by association decreased temperature, may cause a decline in energetic response of pintails to disturbances. Modeled values for energetic response had a mean (± SE) of 175 ± 11.5 kcal/day in year 1, and 111.7 ± 7.22 kcal/day in year 2. Neither the amount of disturbance nor forage availability strongly influenced energetic response. Results of this study raise questions about the efficacy of using behavior or energy expenditure data, alone, to assess anthropogenic disturbance effects on waterfowl.

In long-lived species, such as seabirds, immature survival is the most important life history parameter after adult survival. The assessment of immature survival has often been difficult due to extended periods in which young birds remain unobservable at sea. This study presents results on survival of immature Common Murre (Uria aalge) obtained from an extensive mark-recapture study of a large colony at Stora Karlsö in the Baltic Sea, Sweden. This colony, in contrast with other colonies, has the unique feature that many 1-year-old birds return to the colony (12%). Between 2006 and 2016, 28,930 chicks were marked at fledging, of which 5,493 individuals were later resighted in the colony. Annual survival and recapture probabilities were estimated using Bayesian Cormack-Jolly-Seber models with four age classes for survival probability, and recapture probability being age and time dependent. Informative prior distributions were used to correct partial observability problems in older age classes (observed at breeding ledges). The estimated survival probability of 1-year-old birds was 0.53 (95% CI = 0.49-0.58), 2-year-old birds was 0.87 (0.79-0.96), 3-year-old birds was 0.96 (0.90-0.99), and 4-to-10-year old bird survival probability was 0.63 (0.61-0.64). Survival estimates for younger age classes were consistent with previous studies. Several biological factors may contribute to the observed decline in survival for older age classes.

The global population of Black-bellied Tern (Sterna acuticauda) is declining, and insufficient information is available on its breeding ecology. The aim of this study was to record its breeding ecology and factors affecting breeding success along the Mahanadi River in Odisha, eastern India. Breeding was observed during January-April 2018, with peak activity in March. Among 24 nests recorded on seven sandy islands, only 11 nests successfully produced chicks. Factors affecting survival of nests were flooding due to anthropogenic changes in water levels (54%), predation (31%), and trampling (15%). Dredging of canals that use water from the river is recommended to reduce fluctuations in water levels. Targeted long-term studies along the entire length of the Mahanadi River and other large rivers can aid in identifying other breeding sites and ongoing threats to this rare and endangered species. Outreach in communities near breeding sites and recruiting of local residents as nest guardians can also help in protection of nesting sites.

The White-breasted Waterhen (Amaurornis phoenicurus) is the only bird species known to breed on Pratas Island, Taiwan, for the past few decades. Since they are secretive and very difficult to observe, responses to different call playbacks were tested experimentally in the field to determine if call type affects response of birds to improve future surveys. Playbacks of two different call types (advertising call and aggressive call) were carried out at 26 stations in the east region of the island in April, June, July, and August 2016. The frequency of response and behavioral reaction of waterhens to playbacks were recorded within a 6-min test period at each station. Playbacks of the advertising call elicited more responses at stations than did aggressive calls. Two-way Repeated Measures ANOVA revealed a significant difference in response frequencies for the main effect of call type, but no difference was found for monthly effect and an interaction term for call type and month. This study provides evidence that playback experiments of the advertising call during the courtship period can be an effective way to monitor the population size of a secretive species such as the White-breasted Waterhen.

Investigating the breeding ecology of waterbirds in the Mediterranean is essential for understanding their population dynamics and for conservation purposes. Here, the reproductive parameters of the Little Egret (Egretta garzetta) were investigated in Boughrara Lagoon, a poorly known breeding area in southeastern Tunisia. In total, 152 nests were monitored April-July 2014 from egg-laying to hatching. The nesting period extended from late April to late June, showing three distinct peaks. All nests were constructed < 2 m from the ground in nitre shrubs (Nitraria retusa). Clutch size ranged from 2 to 5 eggs, with a modal clutch of 4 eggs. Average egg volume (± SE) was 25.11 ± 0.08 cm³, which is within the range of known values for the species studied. Using the Mayfield method, hatching rate was estimated at 71%. Our results showed that clutch size and hatching success decreased as the breeding season progressed. This seasonal decrease in breeding performance is in agreement with the general trend in waterbirds and could be explained by the poorer quality of late breeders compared to early ones, or alternatively to the deterioration of environmental conditions late in the breeding season.

First sighting records of rare occurrences may become increasingly important for recognizing changes in distribution, changes in migratory strategies, or increases in hybridization. We documented the first record of a Tundra Bean Goose in the Mississippi Alluvial Valley, the outlet and historic floodplain for much of North America and one of the most important waterfowl wintering areas on the continent. We also document the first genetically confirmed record in the contiguous USA. Bean Goose (Anser fabalis and A. serrirostris) occurrences in North America are rare, especially outside of Alaska. On 24 January 2018, a Tundra Bean Goose (A. s. serrirostris) was harvested by a hunter in a winter-flooded rice field in Desha County, Arkansas, USA, near Dumas. The goose was mixed with a flock of 50 Greater White-Fronted Geese (A. albifrons). Because this individual was legally, albeit accidentally shot, we had the rare and exciting opportunity to obtain morphometric measurements and biological samples. As a result, we were able to verify the species and subspecies through genetic and morphological analysis. We determined the goose was an adult female Tundra Bean Goose, and mitochondrial DNA control region sequence data indicated this specimen was the subspecies A. s. serrirostris.

Roseate Spoonbill (Platalea ajaja) feather samples were collected from nestlings in breeding colonies in the Birama Swamp (n = 34 individuals) and Sabana-Camagüey Archipelago (n = 38 individuals) of Cuba. Genetic diversity and structure were determined from nestling feather samples using five microsatellite loci, and sibling relationships and mating system were inferred. The number of alleles per locus ranged from two to eight, with an average of 5.6 alleles per locus and a total of 28 alleles, and no genetic structure was found between the Cuban colonies. Sibship determined from 52 dyads (nestling-pairs) showed deviation from genetic monogamy, with seven of 24 nests presenting evidence of extra-pair paternity (EPP) and five nests presenting evidence of conspecific brood parasitism (CBP). Genetic diversity was similar to that reported for colonies from the United States and Brazil, and EPP was more frequent than CBP as an alternative to monogamy.