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The objective of this study was to develop tools for distinguishing between sexes of the two Black-crowned Night-Heron (Nycticorax nycticorax) subspecies (N. n. obscurus and N. n. hoactli) using discriminant function analysis. Significant differences were found in length of the culmen, length of the bill from the gape, and length of the wing chord between the sexes of each subspecies, with males being larger than females. The resulting discriminant functions were able to differentiate between the sexes of each studied subspecies and between subspecies after determining the sex of the individuals (with a correct classification of 77.8% for females and 97.8% for males). In females, all morphometrics were greater for N. n. obscurus than N. n. hoactli; this was also the case for males, except for bill width, which was greater in N. n. hoactli. Wing chord length was the most useful measurement for constructing the discriminant functions. External morphometrics are a valuable tool not only for discriminating between N.n. hoactli and N. n. obscurus but also for sexing these subspecies.

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.

During 2011, four separate instances of indirect filial cannibalism, whereby adults consumed their young that died from unknown causes, were observed using video-monitoring techniques in a nesting colony of Black-crowned Night-Herons (Nycticorax nycticorax) on Alcatraz Island. Though they were not observed actively killing their young, in all four observations adult Black-crowned Night-Herons consumed their young following death (i.e., indirect filial cannibalism). We could not determine cause of chick mortality, but parental neglect was likely a contributing factor in at least two instances. Indirect filial cannibalism is not commonly documented among birds, and understanding how cannibalism contributes to nest failure can help researchers better understand factors that limit nesting populations.

Black-crowned night heron ( Nycticorax nycticorax ) eggs have been identified as useful indicators for biomonitoring the environmental pollution in China. In this study, we investigated thirty eggs of black-crowned night heron collected from the upper Yangtze River (Changjiang) Basin, Southwest China, for the occurrence of legacy persistent organic pollutants (POPs), including polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/Fs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). Our results showed a general presence of POPs in night heron eggs with OCPs being the dominant contaminants, having a geometric mean concentration of 22.2 ng g −1 wet weight (ww), followed by PCBs (1.36 ng g −1 ww), PBDEs (0.215 ng g −1 ww), and PCDD/Fs (23.0 pg g −1 ww). The concentration levels were found to be significantly higher in night heron eggs than in poultry eggs by one or two magnitude orders. Among OCP congeners, p,p′-DDE was found to be predominant in night heron eggs, with a geometric mean concentration of 15.1 ng g −1 ww. Furthermore, species-specific congener patterns in eggs suggested similar or different sources for different POPs, possibly associated with contaminated soil and parental dietary sources. Additionally, estimated daily intakes (EDIs) were used to evaluate non-carcinogenic and carcinogenic risk associated with consumption of bird eggs. Our results revealed non-negligible non-cancer and cancer risk for humans who consume wild bird eggs as a regular diet instead of poultry eggs.

The White-eared Night Heron ( Gorsachius magnificus ) is an endangered species facing increasing threats from human activities and ecological changes throughout its fragmented habitat. In this study, we integrate decade-long news data (2015–2024) and systematic field monitoring (2013–2024) to assess the species' distribution, local population trends and conservation challenges in China. Our analysis of 36 verified new reports revealed 14 new distribution sites across 11 provinces. Moreover, there were 17 reports of injuries to the White-eared Night Heron, including five wing injuries, four leg injuries, three eye injuries and five unspecified injuries. Our results suggest that discarded fishing lines, fishhooks and plastic contamination are the main causes of injuries to the species. For the local population, we recorded 12 breeding pairs of this species in Junwu Forest Park, Guangxi, China. However, our data showed a persistent decline in the number of adult individuals, nests and nestlings. The fragmented distribution pattern, combined with the threats it faces, means that, even if more and more of its distribution sites are detected, if adequate protective measures are not taken, its population may still face the danger of local extinction and further reduction. Our study highlights the role of social media data in assessing the population size and distribution of endangered species. From the perspective of species conservation, long-term monitoring programmes should be established in multiple sites across the species' range to provide a comprehensive understanding of population size trends and the effectiveness of conservation efforts.

Objectives A genome sequence of a threatened species can provide valuable genetic information that is important for improving the conservation strategies. The white-eared night heron ( Gorsachius magnificus ) is an endangered and poorly known ardeid bird. In order to support future studies on conservation genetics and evolutionary adaptation of this species, we have reported a de novo assembled and annotated whole-genome sequence of the G. magnificus . Data description The final draft genome assembly of the G. magnificus was 1.19 Gb in size, with a contig N50 of 187.69 kb and a scaffold N50 of 7,338.28 kb. According to BUSCO analysis, the genome assembly contained 97.49% of the 8,338 genes in the Aves (odb10) dataset. Approximately 10.52% of the genome assembly was composed of repetitive sequences. A total of 14,613 protein-coding genes were predicted in the genome assembly, with functional annotations available for 14,611 genes. The genome assembly exhibited a heterozygosity rate of 0.49 heterozygosity per kilobase pair. This draft genome of G. magnificus provides valuable genomic resources for future studies on conservation and evolution.

The nestling diets of four heron species breeding on a small forestry islet in Anzali, Iran, were investigated to determine the dietary segregation among sympatric breeders. Regurgitated samples from Black-crowned Night-Herons (Nycticorax nycticorax), Little Egrets (Egretta garzetta), Cattle Egrets (Bubulcus ibis) and Squacco Herons (Ardeola ralloides) were collected during the breeding season from 23 May to 16 August 2016. A total of 1,606 prey items were identified representing 39 prey categories from nine different classes. Differences were detected among these four ardeid species for the percentage of each prey category. Fish dominated the regurgitates of the Blackcrowned Night-Heron (67%; n = 43 samples), Little Egret (45%; n = 33 samples) and Squacco Heron (53%; n = 10 samples), whereas arachnids and insects combined (53% and 40%, respectively, based on total number of individuals) and insects (61.9% based on weight) were the most common prey items for the Cattle Egret. Although fish items were dominant in Black-crowned Night-Herons, Little Egrets and Squacco Herons, their weight (χ23 = 318, P < 0.001) and length (χ23 = 225.2, P < 0.001) differed significantly. There was some overlap in the diet of all four heron species, especially between Black-crowned Night-Herons and Squacco Herons, with a Pianka Overlap Index equaling 0.92. There was sufficient dietary segregation in terms of number, weight and length of prey items that could contribute to a reduction in competition for limited food resources.

Four cases of interspecific mixed broods between Little Egrets (Egretta garzetta; n = 175), Cattle Egrets (Bubulcus ibis; n = 125), Squacco Herons (Ardeola ralloides; n = 25) and Black-crowned Night-Herons (Nycticoraxnycticorax; n = 199) were recorded from 7 April to 16 August 2016 at two colonies in Iran. The rare occurrence of mixed broods and the low survival of the parasite chicks suggest that brood parasitism is not adaptive in the Ardeidae.

In northwestern Italy, traditional rice cultivation using permanent flooding has been replaced by cultivation that uses a reduced water depth and a shortened submersion period. Prey availability for the numerous herons and egrets using this intensive rice cultivation region changed as well, with a diminution of amphibians and an increase of crayfish (Procambarus clarkii) and oriental weatherfish (Misgurnus anguillicaudatus). The prey intake in 2014 was compared with data available for 1987 for the three most common species of waterbirds that forage in the paddies. Total biomass intake by Grey Herons (Ardea cinerea) feeding in the paddies decreased from 28 g dry mass/min in 1987 to 7 g in 2014, and by Black-crowned Night-Herons (Nycticorax nycticorax) from 8 g to 5 g, while the intake by Little Egrets (Egretta garzetta) remained similar (12 and 13 g in 1987 and 2014, respectively). The observed levels of prey intake allowed breeding Grey Herons to meet their energy needs by feeding exclusively in the rice paddies in 1987, but not in 2014. The other two study species could not meet their daily requirements for successful breeding by feeding in the paddies only, either in 1987 or 2014. Yet the three species bred successfully in the study area, and their reproductive output remained stable both in 1987 and 2014. Successful breeding was probable by the three species foraging in other habitats, such as rivers, small natural wetlands and irrigation canals, in the region.

Nest failure of most pairs of Roseate Terns (Sterna dougallii) at Falkner Island, Connecticut, in 2002–2003 (due mainly to predation by Black-crowned Night-herons [Nycticorax nycticorax]) was followed by the rapid departure of many of the failed individuals in both years. Nine failed pairs (16.7%) stayed while 40 (74.1%) of 54 unsuccessful pairs left within 2 d following nest failure in 2002, and 7 pairs (21.9%) stayed while 25 (78.1%) of 32 unsuccessful pairs left within 2 d in 2003. Individuals that departed this colony site by the end of June likely had time to prospect and renest at another colony site in the same year, and individuals that successfully renested at another colony site could have shown reduced colony-site fidelity to Falkner Island in subsequent years.