Belief that most seabirds return to breed where they had been reared as chicks and exhibit high levels of philopatry and, by implication, have low levels of gene flow, is untenable. In the past, estimates of philopatry have been exaggerated because of the comparative ease of finding individuals returning to their natal area and the difficulty in locating those that have moved away. Measures of philopatry in seabirds obtained from unbiased data show wide between-species variation, and overall it is much lower than was formerly believed. While philopatry is obviously low in species that nest in and move between temporary habitats, it can also be low in colonial species that use the same nesting sites for many years (e.g., cliff-nesting species). Comparisons of the extent of philopatry in other waterbird species show similar variation to those found in seabirds. The expression of philopatry is probably variable within a species and is influenced by environmental conditions and population pressures and so should not be considered a constant for individual species.

The King Rail (Rallus elegans) is a secretive marsh bird of conservation concern. Reproductive success is thought to be a limiting factor for the inland migratory population. Reproductive effort of King Rails was studied in southeastern Oklahoma, USA, from 2010–2012 using surveys, radio-telemetry, nest searching and brood observations. During 2011–2012, 27–29 King Rail territories were documented. Ten nests were located between the first week in April and the first week in July with a mean clutch size of 10.3 (SE = 0.80). Water depth at nests was shallow (< 15 cm), and nest sites were in locations with more visual obstruction, more microtopographic variation, and more woody stems, while open water cover was less than at random sites. Nine broods were followed and were found to use rearing sites that were in deeper water and had a greater percent of tall emergent vegetation and more woody vegetation than random sites. Brood size dropped from an average of nine to two chicks by the second week. Weekly brood survival rate was 0.87 (SE = 0.045), which resulted in a 29% probability of greater than one chick surviving to fledge at 9 weeks. Increasing reproductive success is a management concern for this inland migratory population of King Rails.

Wetland connectivity provides migratory shorebirds varying options to meet energy requirements to survive and complete their annual cycle. Multiple factors mediate movement and residency of spatially segregated wetlands. Information on these factors is lacking in the tropics, yet such information is invaluable for conservation design. The influence of seven biotic and abiotic factors on local movement and residency rates of Semipalmated Sandpipers (Calidris pusilla) among three major wetlands in southwestern Puerto Rico in 2013–2014 was assessed using multi-state models. The model with highest support (AIC_c w_i= 0.78) indicated that weekly residency rates increased seasonally, and were positively influenced by bird abundance and the interaction of prey density and rainfall. Movement rates were negatively influenced by inter-wetland distance, which varied annually, ranging from 0.01 ± 0.004 to 0.33 ± 0.08. Age class (adult, juvenile), extent of shoreline habitat (km), and body condition (estimated percent fat) did not influence residency rates (95% CIs overlapped Betas). Our findings indicated that coastal wetlands in southwestern Puerto Rico were connected, pointing at the joint value of salt flats and mangroves for overwintering Semipalmated Sandpipers. Connectivity between different types of wetlands likely widens resource diversity, which is essential for coping with unpredictable environments. Additional work is needed to generalize our understanding of inter-wetland dynamics and their potential benefits to inform shorebird conservation strategies in the Caribbean.

In numerous avian species, egg size is correlated to female body condition, hatchling size and nestling growth. Recent demography studies of Interior Double-crested Cormorants (Phalacrocorax auritus) suggest a migratory divide across the Great Lakes; western populations winter in the Gulf of Mexico region of the southeastern United States (Alabama, Arkansas, Louisiana, and Mississippi) with extensive catfish (Ictalurus punctatus) aquaculture, and eastern populations winter in Florida, where catfish aquaculture is not pervasive. If Double-crested Cormorants have improved their overall body condition through catfish exploitation, then egg and chick sizes should also be affected. Three breeding areas in Ontario (east, central, and west) were selected for empirical measures of size variation. During the breeding seasons of 2006 and 2007, egg, naked young, fledgling, and adult morphometric data were collected. Eggs in eastern areas (volume = 465.8 ± 3.9 cm³) were on average larger than eggs in central (volume = 458.1 ± 3.5 cm³) and western (volume = 451.7 ± 3.5 cm³) areas. However, chicks in eastern areas (culmen = 54.9 ± 0.6 mm) were smaller than chicks in central (culmen = 57.6 ± 0.4 mm) and western (culmen = 59.3 ± 0.3 mm) areas, not only at hatching, but throughout development and fledging. A comprehensive Double-crested Cormorant morphometric gradient that may suggest a potential reproductive advantage for birds exploiting aquaculture facilities is presented.

Breeding King Rails (Rallus elegans) have become more reliant on coastal marshes, but these are prone to variation in water level influenced by estuarine effluent and storm surge. Nest-building behavior in King Rails was studied in a natural coastal marsh subjected to a wind-driven tide system, where rapid water level rise from storm surge has led to nest inundation. To determine whether breeders exhibited plasticity in nest building in response to water level variation, nest height and water level were monitored at 2- to 3-day intervals, and video was used to quantify building behavior. Average height varied substantially among King Rail nests, indicating plasticity in overall building effort. King Rails constructed significantly taller nests at sites with greater variation in water level. Parents spent a greater proportion of time nest building when the water level was closer to the nest rim. The majority of nest accumulation occurred before laying ceased. Though King Rails continue to build through the nesting cycle, which is likely to counteract settling and improve the structural integrity of nests, they may not be able to increase nest height quickly enough to avoid flooding when faced with rapidly rising water.

Waterbird survival rates are a key component of demographic modeling used for effective conservation of long-lived threatened species. The Swan Goose (Anser cygnoides) is globally threatened and the most vulnerable goose species endemic to East Asia due to its small and rapidly declining population. To address a current knowledge gap in demographic parameters of the Swan Goose, available datasets were compiled from neck-collar resighting and telemetry studies, and two different models were used to estimate their survival rates. Results of a mark-resighting model using 15 years of neck-collar data (2001–2015) provided age-dependent survival rates and season-dependent encounter rates with a constant neck-collar retention rate. Annual survival rate was 0.638 (95% CI: 0.378–0.803) for adults and 0.122 (95% CI: 0.028–0.286) for first-year juveniles. Known-fate models were applied to the single season of telemetry data (autumn 2014) and estimated a mean annual survival rate of 0.408 (95% CI: 0.152–0.670) with higher but non-significant differences for adults (0.477) vs. juveniles (0.306). Our findings indicate that Swan Goose survival rates are comparable to the lowest rates reported for European or North American goose species. Poor survival may be a key demographic parameter contributing to their declining trend. Quantitative threat assessments and associated conservation measures, such as restricting hunting, may be a key step to mitigate for their low survival rates and maintain or enhance their population.

Satellite telemetry was used to investigate summer and winter home ranges for resident and migrant American White Pelicans (Pelecanus erythrorhynchos) captured in the southeastern United States between 2002 and 2007. Home range utilization distributions were calculated using 50% and 95% kernel density estimators with the plug-in bandwidth selector. Mean summer home ranges (95%) varied from 177 to 4,710 km² and mean winter home ranges (95%) ranged from 185 to 916 km². Mean 50% and 95% home ranges of adult American White Pelicans during summer tended to be larger than those during winter, whereas mean 50% and 95% home ranges of immature pelicans during summer tended to be smaller than those during winter. Home ranges for all American White Pelicans encompassed the latitude range of 24°–55° N, including wintering, stop over, and nesting habitat. These data provide baseline movement and home range data for future studies of American White Pelican ecology.

To provide an easy and reliable work tool to identify the sex of individuals, adult Black-browed Albatrosses (Thalassarche melanophrys) (n = 31) were weighed and measured, and the sex determined using DNA analyses. Stepwise discriminant analysis showed upper bill depth and weight to be the best predictor variables for sex determination. This model classified correctly 95.0% of the males and 81.8% of the females (overall success was 90.3%). Additionally, a single measure discriminant analysis of upper bill depth was developed that is able to separate sexes using a threshold upper bill depth of 29.87 mm, with values above this point being males and values below it being females.

The breeding biology of Australian Pelicans (Pelecanus conspicillatus) was studied on the coast of South Australia between 2002 and 2004. This study aimed to compare breeding on the coast with previous studies of inland breeding Australian Pelicans and to test whether this species exhibits siblicidal brood reduction. Nests were generally constructed on the ground in spatially and temporally discrete colonies. Nests within colonies were 1.3 ± 0.5 m apart (Range = 0.6–4.5; n = 327), whereas colonies were 329 m apart (Range = 21–1,136; n = 63). Within colonies, 80% of nests were initiated within 10 days of each other. Colonies contained 41.0 ± 37.6 nests (Range = 1–148; n = 63). Most colonies were initiated during the austral winter and spring (June–September) in contrast to opportunistic breeding in inland areas. Clutch size averaged 1.92 ± 0.36 eggs (Range = 1–4; n = 2,297), and incubation lasted 32 days (Range = 28–38; n = 57). Hatching success averaged 41.5 ± 38.6% (Range = 0–99; n = 24 colonies), the number of nestlings that survived to join a crèche was 20.3 ± 22.4% (Range = 0–66; n = 24 colonies), and fledging success averaged 15.3 ± 18.3% (Range = 0–61; n = 24 colonies). Aggression among nestlings and resulting wounds were observed in 48% of broods (n = 64). Mortality during the 10-day nestling period was high (5.5 ± 2.2%/day; Range = 2.5–10.0; n = 45) and was the major determinant of overall breeding success. These findings suggest that Australian Pelicans exhibit siblicidal brood reduction.

Identifying parasitized nests and eggs is a prerequisite for studying conspecific brood parasitism. Previous studies on the effectiveness of egg morphology to identify parasitic eggs of different species have produced mixed results. Brood parasitism and egg measurements (length, width and weight) were monitored in Common Coot (Fulica atra; n = 85) nests. Maximum Euclidean distance was calculated for each nest. Results indicated that maximum Euclidean distance values of non-parasitized and parasitized nests were significantly different (t₈₃ = 9.747, P < 0.01). The optimal split value of recursive partitioning analysis for Common Coot nests was 2.98 (R² = 0.65), which can identify 93.3% non-parasitized and 88.0% parasitized nests successfully. However the most dissimilar egg in parasitized nests calculated by maximum average Euclidean distance only identified 39.3% of the parasitic eggs correctly. Egg morphology is effective for detecting conspecific brood parasitism of Common Coot nests, but is not accurate enough to determine parasitic eggs. As a result, this method should be used with caution and combined with observational or molecular biology methods.

Collisions with power lines are a widely documented cause of avian mortality. Estimating total mortalities from counts of carcasses is usually accomplished by quantifying biasing factors, but neither crippling nor nocturnal biases are well understood. From 4 March through 13 April 2009, data were collected on Sandhill Crane (Grus canadensis) collisions involving a 69-kV transmission line crossing the Platte River in Nebraska, USA, at a major migration stopover area. The line was marked with devices designed to increase visibility to Sandhill Cranes, and thus reduce collisions. Numbers of carcasses detected via traditional searches that involved walking slowly in a zigzag pattern beneath the line were compared to numbers of collisions visually observed through binoculars and night vision spotting scopes and numbers of collisions detected by electronic Bird Strike Indicators (BSI). Seventeen carcasses were found during traditional surveys, 117 collisions were observed visually, and 321 collisions were recorded by BSIs. Most collisions occurred at night, with crippled Sandhill Cranes departing survey transects. Total mortality, including crippling and nocturnal biases, was 2.8 to 3.7 times greater than indicated by a traditional corrected-count mortality estimator. Neither crippling bias nor nocturnal bias were adequately considered by the traditional estimator. Consistent with other studies of avian collision, line marking was only partially successful in reducing collisions.

The diet of the Little Tern (Sternula albifrons), an estuarine seabird species breeding in southern Portugal, was determined by separately identifying fish otoliths and scales found in pellets. Using both fish otoliths and scales showed that the diet of Little Terns was mainly composed of sand-smelts (Atherina spp.), but there were differences in secondary prey items. Species such as sardine (Sardina pilchardus), with very small and easily degraded otoliths, showed a higher percentage of occurrence in the diet using scale analysis. This study suggests that both methods should be used together to evaluate the diet of small estuarine seabird species.

Semipalmated Sandpipers (Calidris pusilla) and Lapland Longspurs (Calcarius lapponicus) share similar nesting habitat preferences on small islands in the Mackenzie River Delta, Northwest Territories, Canada. A Semipalmated Sandpiper was observed incubating a mixed clutch of its own eggs with two smaller eggs presumed to be from a Lapland Longspur. This is a unique combination of a precocial and an altricial species' eggs in the same nest. Possible explanations for the occurrence of this interspecific mixed clutch include nest parasitism, accidental laying, opportunistic egg dumping, or nest usurpation.