The Yellow Rail (Coturnicops noveboracensis) is a migratory bird with many aspects of its ecology poorly understood. The objective of this study was to examine effects of fire, vegetation structure, and landscape variables on site occupancy and detection probabilities for Yellow Rails overwintering in coastal pine savannas of Mississippi and Alabama. Between December and April, 2012–2013, dragline surveys for Yellow Rail were conducted at three conservation areas: two in Jackson County, Mississippi, and one in Mobile County, Alabama, USA. Site occupancy for Yellow Rail was 0.81 ± 0.06 (SD) with detection probabilities of 0.79 ± 0.09 (SD). Yellow Rail occupancy related negatively with time since fire, indicating fire provides conditions attractive to Yellow Rail overwintering throughout the study area. Yellow Rail use of wetland and fire-maintained habitats within coastal Mississippi during winter, coupled with continued loss of open grasslands and inadequate management of fire-dependent pine savanna habitats throughout the southeastern USA highlights the continued need to prioritize the conservation and effective management of herbaceous-dominated ecosystems.

Contrasting the general trend of declining Afro-Palearctic migratory bird populations, the Whiskered Tern (Chlidonias hybrida hybrida) has recently exhibited spectacular demographic expansion and range shifts across its patchy European breeding distribution. To explore population connectivity of this species, individuals sampled from four sites in France, Poland, and Ukraine (n = 78) were genotyped at six microsatellite DNA loci and one partial mitochondrial cytochrome-b gene. Genetic variation was generally high (H_E = 0.47-0.67; π = 1.29-2.26). Contrasting the historical absence of significant genetic structure (Φ_ST = 0.061-0.027), the microsatellite data indicated strong differentiation between France and the Eastern European sites (F_ST = 0.067-0.098). This, coupled with evidence of two distinct genetic clusters (K = 2; ΔK = 2) corresponding to little subdivision between Poland and Ukraine, has confirmed the presence of two European Whiskered Tern subpopulations (western and eastern) characterized by stark differences in wintering distribution and seasonal migratory routes.

Plasma biochemistries provide a complementary method for assessing physiological and nutritional status of free-ranging wild birds. Triglycerides, total protein and alkaline phosphatase were determined in 110 free-living Imperial Cormorant (Phalacrocorax atriceps) chicks aged 16-35 days, at Punta León (Argentina) during 2010 and 2011. Body mass at 30 days of age (“pre-fledging body condition”, 2010 only) and body mass corrected by tarsus length at the time of blood sampling (“current body condition”, 2011 only) were also determined. Variability of parameters by sex, hatching order, survival, age and breeding season was assessed, and the relationship between biochemical and morphometric indices was also explored. Morphometric indices were higher in A-chicks (pre-fledging body condition also varied with sex), and explained 35-55% of B-chick survival. Biochemistries differed significantly between breeding seasons, being higher in 2011. Alkaline phosphatase increased with age, and total protein was higher in A-chicks. Triglycerides and total protein accounted for 26% and 30%, respectively, of variation in current body condition; however, they did not forecast pre-fledging body condition. Lastly, total protein levels predicted B-chick survival (higher levels in surviving B-chicks), but their prognostic value was relatively low. The results suggest that unlike morphometric indices, the biochemistries chosen are valuable to assess individual body condition at the time of sampling, yet their applicability for predicting chick survival requires further evaluation.

The diversity and abundance of wetland birds have been threatened by increasing anthropogenic activities during recent decades. The objective of this study was to determine the effect of human-induced disturbance on bird species richness and abundance of natural wetlands in southwest Ethiopia. Bird surveys were performed at 56 locations during both the wet and dry seasons in 2010 and 2011. Generalized linear modeling (G) was used to correlate species richness with environmental variables. It was found that wetlands with low human disturbance were characterized by a higher richness (n > 10) of wetland dependent specialist birds (depending completely on wetlands for food and nesting) than the highly disturbed wetlands. However, for wetland-associated birds (those able to nest and feed in wetlands as well as in other habitats), there was no significant difference (P = 0.31) in species richness between disturbed and non-disturbed wetlands. The abundance of wetland dependent specialist birds was significantly affected (P < 0.001) by human disturbance, whereas the abundance of wetland associated birds was not (P = 0.39). Fifty-three percent of the variation in species richness of wetland dependent birds was explained by a combination of water depth, sludge depth, conductivity, chlorophyll a, total phosphorus, human disturbance and vegetation cover. It is recommended that anthropogenic activities should be minimized and controlled in and around these wetlands to conserve biodiversity.

Sexual size dimorphism and geographic variability in external measurements of the Grey-faced Petrel (Pterodroma gouldi) were investigated on the west and east coasts of the North Island of New Zealand. The applicability of morphometrics to distinguish the sex of individuals in the two geographic areas and assign a geographic origin to individuals was evaluated. Low geographic variation in morphometry was found, with discriminant function analysis failing to develop an efficient function to assign a geographic origin (55.9% accuracy). In contrast, sexual size dimorphism was marked (up to 6.6% different), with males being significantly larger than females in all measurements but wing length. A discriminant function combining bill depth at nostrils and head length correctly predicted sex of adult breeders with 80.9% accuracy (78.9% for males, 82.7% for females). Despite its apparent applicability across the entire range of the species, this discriminant function was not sufficiently accurate on its own. Alternatively, the use of bill depth at the base or a bill size index increased sexing accuracy to 92.1% when both mates of pairs were considered. Thus, Grey-faced Petrels can be reliably sexed by taking only one measurement on both mates of a pair.

Cormorants and shags (Phalacrocoracidae) are sexually monomorphic in plumage but dimorphic in size with males larger and heavier than females. Such size dimorphism has been capitalized upon for several species in the family to sex adults by using discriminant analysis applied on the morphometric measurements. Despite that, few studies have analyzed the development of sexual size dimorphism during chick growth. In this study, sexspecific growth was assessed in chicks of the Imperial Cormorant (Phalacrocorax atriceps) by analyzing the development of body mass, bill length, head length, tarsus length and wing length measured on 80 chicks sexed by DNA-based technics. Fieldwork was performed during the 2004 breeding season at Punta León, Patagonia, Argentina. In addition, discriminant analyses were performed to obtain functions to determine the sex of fledglings. Males had higher asymptotic values and growth rates than females for all measurements considered, even though the arising of dimorphism varied among morphometric characteristics (10-40 days). Discriminant functions to determine the sex of chicks at 30, 35 and 40 days of age were obtained. All functions included tarsus length and head length as variables, correctly classifying 88-94% of chicks. Our findings show the Imperial Cormorant to be an interesting model for evaluating the potential consequences of sexual size dimorphism on chick survival and fledging condition depending on brood sex composition.

Several studies have applied induced regurgitations to characterize the diet of cormorants, but none have presented quantitative information indicating complete stomach contents were obtained. Our goal was to test the value of induced regurgitations for the assessment and monitoring of Imperial Cormorant (Phalacrocorax atriceps) diet. Stomach samples were obtained from male and female breeding adults bringing food back to the colony during the chick rearing stage (n = 22) at Isla Arce, Argentina. Samples were obtained through induced regurgitation, and immediately afterward each individual was flushed with sea water. The diet of the Imperial Cormorant consisted of at least 23 prey taxa, mostly fish complemented by crustaceans, cephalopods and polychaetes. However, only Argentine anchovy (Engraulis anchoita) and rockcods (Patagonotothen spp.) showed a significant contribution by mass (70.7% and 25.3%, respectively). Analysis of similarity indicated that prey composition between samples obtained by induced regurgitation and those obtained by combining regurgitation followed by stomach flushing were similar in both the numerical frequency of all prey taxa recorded and the contribution by mass of the main prey. Our results show that induced regurgitation provides complete stomach contents, and thus validates the use of this technique for quantifying Imperial Cormorant diet composition.

Aechmophorus grebes are socially monogamous and copulate only on floating nests. Motion-activated cameras were used to study the copulation behavior of Aechmophorus grebes at Clear Lake, Lake County, California, USA, during 2015–2016. The sex of both partners was determined in 226 of 435 copulations; of these, 8.0% were female mounting male (reverse mountings), including 6.4% by Western Grebe (A. occidentalis; n = 171), 0% by Clark's Grebe (A. clarkii; n = 31), and 42.9% by mixed pairs (n = 14). One copulation comprised two Western Grebes mounting a third individual on a nest; the sexes could not be determined, but most likely consisted of two males mounting a female. Another copulation comprised a male-male mounting by Western Grebes. These records provide the first documentation of simultaneous extra-pair copulation and male-male mounting in the Western Grebe.

White-eared Night-Herons (Gorsachius magnificus) have been observed throughout their range, but their life history is still poorly understood, especially breeding parameters prior to 2007. This study was conducted on the breeding parameters of White-eared Night-Herons, from April 2009 to July 2015, in two artificial forests of southern China. All nests were located on two crossing branches of Masson's pine (Pinus massoniana) with altitudes ranging from 123–248 m. Most (88.9%; n = 18) White-eared Night-Heron pairs began breeding in March and completed breeding in July. They consistently laid three eggs, hatching on average 2.88 ± 0.49 (n = 17; Range = 1–3) nestlings and fledging on average of 2.17 ± 1.38 (n = 18; Range = 0–3) fledglings per nest. Tree felling and human disturbance were the two most important factors influencing the breeding success of White-eared Night-Herons in the artificial forests. These results suggest that White-eared Night-Herons have a strong adaptability in breeding behavior in pine trees of artificial forests.

Many bird species of conservation concern have behavioral or morphological traits that make it difficult for researchers to determine if the birds have been uniquely marked. Those traits can also increase the difficulty for researchers to decipher those markers. As a result, it is a priority for field biologists to develop time- and cost-efficient methods to resight uniquely marked individuals, especially when efforts are spread across multiple States and study areas. The Interior Least Tern (Sternula antillarum athalassos) is one such difficult-to-resight species; its tendency to mob perceived threats, such as observing researchers, makes resighting marked individuals difficult without physical recapture. During 2015, uniquely marked adult Interior Least Terns were resighted and identified by small, inexpensive, high-definition portable video cameras deployed for 29-min periods adjacent to nests. Interior Least Tern individuals were uniquely identified 84% (n = 277) of the time. This method also provided the ability to link individually marked adults to a specific nest, which can aid in generational studies and understanding heritability for difficult-to-resight species. Mark-recapture studies on such species may be prone to sparse encounter data that can result in imprecise or biased demographic estimates and ultimately flawed inferences. High-definition video cameras may prove to be a robust method for generating reliable demographic estimates.

Predation of vertebrates by Mallards (Anas platyrhynchos) has rarely been documented and only in relation to fish and amphibians. Mallard foraging behavior was observed at a reservoir bordering Semenic-Caras Gorges National Park in southwest Romania. A group of Mallards comprising one adult female and 10 subadults was recorded hunting, killing and consuming hatching year passerine birds of two species, a Grey Wagtail (Motacilla cinerea) and a Black Redstart (Phoenicuros ochruros). These are the first records of hunting of birds by wild Mallards. This extraordinary new behavior represents substantial diet expansion for this widespread and abundant duck species.