The Reddish Egret (Egretta rufescens) inhabits Cuban coastal saline habitats, although the number of individuals and specific breeding and foraging locations are largely unknown. Unpublished fieldwork data, as well as data coming from scientific literature, zoological collections and eBird, were collated to assess the Reddish Egret breeding population and number of foraging individuals in Cuba. A total of 155 breeding pairs, which represent 3% of the estimated global population and 22% of the estimated regional population (i.e., Eastern Management Unit), were confirmed. Most of the breeding reports were distributed within the Sabana-Camagüey archipelago (54%, n = 13 breeding areas). Foraging Reddish Egrets were common throughout Cuba's coastal saline habitats and were documented in most of the localities referred to in published and unpublished sources (88%, n = 65 sites). These observations accounted for a maximum of 544 birds (n = 20 sites), which represent 7–10% of the global population estimate. Four of the foraging sites accounted for 69% (n = 544) of the overall foraging population. The evidence suggests that Cuba should be considered an area of great importance for Reddish Egret conservation.

In birds where males and females are similar in size and plumage, sex determination by alternative means is necessary. Discriminant function analysis based on external morphometrics was used to distinguish males from females in two closely related species: Western Grebe (Aechmophorus occidentalis) and Clark's Grebe (A. clarkii). Additionally, discriminant function analysis was used to evaluate morphometric divergence between Western and Clark's grebe adults and eggs. Aechmophorus grebe adults (n = 576) and eggs (n = 130) were sampled across 29 lakes and reservoirs throughout California, USA, and adult sex was determined using molecular analysis. Both Western and Clark's grebes exhibited considerable sexual size dimorphism. Males averaged 6–26% larger than females among seven morphological measurements, with the greatest sexual size dimorphism occurring for bill morphometrics. Discriminant functions based on bill length, bill depth, and short tarsus length correctly assigned sex to 98% of Western Grebes, and a function based on bill length and bill depth correctly assigned sex to 99% of Clark's Grebes. Further, a simplified discriminant function based only on bill depth correctly assigned sex to 96% of Western Grebes and 98% of Clark's Grebes. In contrast, external morphometrics were not suitable for differentiating between Western and Clark's grebe adults or their eggs, with correct classification rates of discriminant functions of only 60%, 63%, and 61% for adult males, adult females, and eggs, respectively. Our results indicate little divergence in external morphology between species of Aechmophorus grebes, and instead separation is much greater between males and females.

Male and female Dunlin (Calidris alpina) exhibit slight plumage and structural differences. Discriminant function analysis based on morphological characteristics can effectively differentiate between sexes in several subspecies of Dunlin. We assessed the level of sexual size dimorphism in a subspecies that breeds in sub-Arctic Canada (C. a. hudsonia), and used discriminant function analysis to create equations to classify individuals to sex using five body measurements (body mass, head length, culmen length, tarsus length, and flattened wing chord). Females were significantly larger than males for all body measurements. Discriminant function analysis using tarsus length, head length, and body mass correctly classified 87.1% of molecularly sexed females (n = 31) and 92.6% of males (n = 27). The classification of an independent sample (n = 12) resulted in 100.0% correct assignment of sex with 33.3% of individuals falling within the undetermined range. A discriminant function analysis equation is provided for use with non-breeding populations using only structural characteristics with classification accuracies of 83.9% for females and 81.5% for males. The resulting equations from this study have classification accuracies comparable to those equations developed for other Dunlin subspecies and can be used to reliably differentiate sexes of C. a. hudsonia using body measurements collected in the field.

Allometric scaling law predicts that herbivores respond differently to the availability of resources, mediated by body size. However, studies of allometric responses have often focused on animals with a relatively large difference in body size. Here, using a correlative field study, habitat use by two herbivorous species, the Bean Goose (Anser fabalis) and the Greater White-fronted Goose (A. albifrons), with a relatively small difference in body size was investigated during the wintering period. Both a generalized linear mixed model and a mixed logistic regression model showed that both species selected lower lying areas that were recently exposed, and, as expected, the smaller Greater White-fronted Goose showed a stronger selection of foraging habitat than the larger Bean Goose. Sward height also influenced habitat selection by both species, and the smaller species selected shorter swards than the larger species. In terms of forage quality, both models failed to detect a significant effect of nitrogen content on goose habitat selection. A logistic regression model showed that structural heterogeneity of the sward negatively correlated with the patch selection of the smaller species, but for the larger species such a correlation was not found. In agreement with our hypotheses, our results provide some preliminary indication that coexistence of the two goose species studied here might be mediated by an allometric response even if the difference in body size is relatively small.

Coastal Louisiana has suffered from dramatic coastal land loss. Following translocations to Louisiana in the late 1960s, Brown Pelican (Pelecanus occidentalis) colonies were annually surveyed between 1971 and 2010 using aerial methods. The goals of this study were to describe long-term Brown Pelican colony dynamics, investigate physical changes to nesting islands via satellite imagery, and relate colony dynamics to physical island changes. Thirty Brown Pelican colonies were found, with a mean colony persistence of 5.5 years. Following exponential growth up to 2000, nesting plateaued, declined sharply in 2006 primarily due to land losses following the intense 2005 hurricane season, and stabilized at lower levels until 2010. From 1998 to 2010, island size decreased by a mean of 68.7%, with 10 of the islands vanishing entirely. Colony size was positively correlated to island size. Colonies did not shift between State regions, but appeared to shift within regions. To persist in Louisiana, Brown Pelicans will need to continue adjusting to a changing coastline, as well as planned coastal restoration projects. Future monitoring of Brown Pelicans in Louisiana may provide insight into their adaptive responses to changing availability and suitability of nesting island habitat.

The Isles Dernieres Barrier Island Refuge in Louisiana, USA, constitutes a major colonial waterbird breeding site, and several restoration projects have been undertaken to sustain waterbird populations on the refuge. However, very little is known about food resources that colonial waterbirds depend on in the Gulf of Mexico. Royal (Thalasseus maximus) and Sandwich (T. sandvicensis) tern diet composition was investigated to determine important food resources during the breeding period. Regurgitated prey items in the 2013 and 2014 breeding seasons were used to compare diet composition, prey item frequency, and prey item mass among four groups: Royal Tern adults, Royal Tern chicks, Sandwich Tern adults, and Sandwich Tern chicks. The two most frequent prey items were Atlantic croaker (Micropogonias undulatus) and bay anchovy (Anchoa mitchilli). Royal Tern adults consumed significantly more Sciaenids than any other tern group, and Sandwich Tern adults consumed more Engraulids than any other tern group. Royal and Sandwich tern adults partitioned food resources by prey species and prey size, while chick diet showed more overlap in prey species composition. Royal and Sandwich tern diet closely reflected the species composition of trawls from nearby waters, suggesting opportunistic prey selection. The diets of both tern species contained a variety of demersal prey items indicating use of discards from local fisheries activities. Interactions between breeding waterbirds and fisheries in coastal Louisiana may be an important conservation consideration with profound implications on breeding abundance and breeding success of waterbirds.

The Gray Gull (Leucophaeus modestus) has the unique habit among gulls of nesting in the interior Atacama Desert, up to 100 km from the coast. During the 2014–2015 austral breeding season, two breeding colonies were recorded on the coast within 90 m of the shoreline in the Antofagasta Region, northern Chile. The new colonies ranged in size from 40 (Playa Grande) to 150 (Playa Brava) nests. Egg laying was synchronous in both colonies and most likely occurred in late November 2014, coinciding with egg laying in desert colonies. The colony at Playa Brava was successful, but the one at Playa Grande was deserted due to feral dog (Canis familiaris) attacks. The habitat used by Gray Gulls resembled that reported for desert colonies, with flat plains covered with small rocks, which provide protection to chicks from intense solar radiation. This unusual coastal nesting behavior could result in the modification of certain life history and behavioral traits in the Gray Gull (e.g., chick growth rates, energy expenditure, and foraging ranges), which have evolved to breed in severe desert conditions. We suggest that coastal breeding is adopted by Gray Gulls during El Niño years in response to reduced food supply. During El Niño years, Gray Gulls would move to the coast where access to food is better and thermoregulatory costs are lower, but predation is higher. During non-El Niño years, Gray Gulls would resume their ancestral desert-nesting strategy in which traveling distances between the coast and nesting grounds are considerable and thermoregulatory costs are higher, but predation risks are lower. Future observations should confirm if Gray Gulls continue breeding at coastal sites during El Niño years or if this becomes a regular behavior independent of oceanographic conditions.

Shelterbelts are long rows of trees planted in the Great Plains of North America to reduce wind erosion of soil. Shelterbelts alter airflow, creating updrafts on the windward side (updraft zone), slow winds immediately on the leeward side (calm zone), and increased turbulence farther downwind of the shelterbelt (turbulent zone). They also provide hunting perches for avian predators and serve as corridors for mammalian predators. By determining the fate of 247 duck nests located in 27 Waterfowl Production Areas during 2006 and 2007, this study tested the hypothesis that duck nests located close to shelterbelts are more likely to be depredated than nests located in open fields and that nest densities are lower near shelterbelts than in open fields. Nest density in a shelterbelt's calm zone (0.22 nests/ha) was lower than in open fields (1.02 nest/ha). Shelterbelt orientation and porosity to airflow did not affect nest success or nest density. Shelterbelt height did not influence nest density, but nest success decreased as shelterbelts increased in height. Depredation rates were higher for nests near isolated structures (e.g., isolated trees, snags, and utility poles) than for nests near shelterbelts or in open fields.

Double-crested Cormorants (Phalacrocorax auritus) are intensely managed through culling in North America to reduce presumed damage to commercial and natural resources. To evaluate this management, there is a critical need to understand the reproductive biology of Double-crested Cormorants. Gonadal development, reproductive potential and breeding status were determined by necropsy for 1,781 Double-crested Cormorants salvaged each month of the year from control programs in their wintering and breeding ranges in seven States in the USA. Gonadal development of males peaked earlier in the year than females. Mean and maximum reproductive potential was five and 13 ovum, respectively. The average proportion of non-breeding female Double-crested Cormorants culled from breeding colonies was 14.9% (n = 202) and from foraging flocks on the breeding grounds was 22.1% (n = 358). This demographic information should be considered when evaluating and modeling effects of Double-crested Cormorant management in North America.

Small sized, man-made, perennial and primarily rain-fed ponds occur widely in the rural landscape of India. These wetlands provide suitable habitats and food resources for a wide variety of resident and migratory wetland birds. Wetland birds in six rural ponds of Kurukshetra District, Haryana, in northern India were surveyed from April 2011 to May 2014 to determine status. Point counts and direct observations were used to record bird species. Sixty-nine species of wetland birds belonging to 47 genera and 20 families were identified. Family Anatidae dominated the avifauna with 20% (n = 14) of the species found. Of the species documented, 54% (n = 37) were winter migrants, 7% (n = 5) were summer migrants and 39% (n = 27) were residents. Among recorded species, Darter (Anhinga melanogaster), Painted Stork (Mycteria leucocephala), Oriental White Ibis (Threskiornis melanocephalus) and River Tern (Sterna aurantia) are considered as near threatened; Comb Duck (Sarkidiornis melanotos), Brahminy Kite (Haliastur indus) and Eurasian Spoonbill (Platalea leucorodia) are listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. The occurrence of migrants and special-status species documents the importance of these rural ponds as habitats for wetland birds in India. However, anthropogenic and developmental activities in and around these ponds are posing significant threats. The present study provides baseline information on wetland birds of these ponds for future monitoring, conservation planning and the development of pertinent management interventions.

This study was carried out at Ichkeul National Park, Tunisia, during 2009 and 2010. The influence of environmental variables on the foraging behavior of three Ardeid species was studied. Grey Herons (Ardea cinerea) were the least active of the three species, having the greatest resting percentages in 2009 (55.0%) and 2010 (64.9%); they primarily used the “standing and wait” hunting behavior (68.5%). Great Egrets (A. alba) (93.6%) and Little Egrets (Egretta garzetta) (86.5%) primarily adopted a “walking slowly” strategy. Little Egrets also frequently used the “walking quickly” behavior, a more active hunting technique. Both Little and Great egrets varied their hunting behaviors according to water depth. In shallows, they used the “walking quickly” behavior, while in deeper waters they used the “standing and wait” behavior (Little Egret: r = -0.26, P < 0.001; Great Egret: r = -0.44, P < 0.01). For Little Egrets only, high temperature (F = 42.77, df = 1, P < 0.001) and high wind velocity (F = 63.81, df = 1, P < 0.001) promoted an active “walking quickly” hunting behavior, while high light intensity frequently promoted the “standing and wait” and “walking slowly” behaviors (F = 5.48, df = 1, P < 0.05).

Breeding of Wood Storks (Mycteria americana) in western Mexico is limited to a few known sites from Guerrero to Chiapas. However, except for nesting at one Oaxaca site in 2005, all the colonies were reported over 35 years ago, while more recently published bird surveys in coastal wetlands of western Mexico have not reported any nesting Wood Storks. During April 2014, a newly established colony at Mogote Prieto, a mangrove-fringed island in Laguna Cuyutlán's Basin III, Colima, was documented. This colony was visited on seven occasions during the spring and summer of 2014 and 2015. Maximum numbers in 2014 were 300 adult Wood Storks, including 36 clearly on nests and four carrying nesting materials (15 April 2014); 17 large, feathered chicks (12 June 2014); and 15 fledglings (12 July 2014). During 2015, there were fewer adults and nests, but more fledglings (n = 25 on 20 July 2015). Although the source of the nesting adults cannot be established, attention should be given to the conservation of this Wood Stork colony in western Mexico.

Vigilance is a behavior in birds that is used to detect predators and monitor rivals, and it can be affected by several environmental and social factors, including group size. Here, Black-necked Cranes (Grus nigricollis) were observed in winter in the Yarlung Zangbo Nature Reserve, Tibet, China, to examine the effect of group size on vigilance behavior at both the individual and group levels. At the individual level, individual Black-necked Cranes in large social groups spent less time in vigilant behavior than when in small family groups. At the social group level, the proportion of vigilant individuals decreased, while the proportion of intervals that at least one individual was vigilant increased, with increasing group size. There was a significant group size effect on vigilance behavior in wintering Black-necked Cranes at both of these levels.