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Avian responses to high environmental temperatures include retreating to cooler microsites and/or increasing rates of evaporative heat dissipation via panting, both of which may affect foraging success. We hypothesized that behavioural trade-offs constrain the maintenance of avian body condition in hot environments, and tested predictions arising from this hypothesis for male Southern Yellow-billed Hornbills (Tockus leucomelas) breeding in the Kalahari Desert. Operative temperatures experienced by the hornbills varied by up to 13 °C among four microsite categories used by foraging males. Lower prey capture rates while panting and reductions associated with the occupancy of off-ground microsites, resulted in sharp declines in foraging efficiency during hot weather. Consequently, male body mass (M b) gain between sunrise and sunset decreased with increasing daily maximum air temperature (T max), from ~ 5% when T max < 25 °C to zero when T max = 38.4 °C. Overnight M b loss averaged ~ 4.5% irrespective of T max, creating a situation where nett 24-h M b loss approached 5% on extremely hot days. These findings support the notion that temperature is a major determinant of body condition for arid-zone birds. Moreover, the strong temperature dependence of foraging success and body condition among male hornbills provisioning nests raises the possibility that male behavioural trade-offs translate into equally strong effects of hot weather on female condition and nest success. Our results also reveal how rapid anthropogenic climate change is likely to substantially decrease the probability of arid-zone birds like hornbills being able to successfully provision nests while maintaining their own condition.

The Brown Hornbill ( Anorrhinus austeni ), a Near Threatened frugivore, reaches the northern edge of its distribution in southern Yunnan, China, yet breeding had not been previously documented with site‐attributed nests in the country. In April and May 2025, we documented two active nests in the Mengman sector of the Shangyong Protected Area, separated by ~3.5 km. Both involved sealed incubation or brooding by females attended by multiple males, providing the first definitive evidence of cooperative breeding in the species in China. One cavity occurred in a tall Choerospondias axillaris tree and was provisioned with Dysoxylum gotadhora and D. binectariferum fruits, together with insect prey such as mantis and cicadas. The other was in a tall Terminalia myriocarpa tree beside a stream gully, with food deliveries including Ormosia hosiei and Pometia tomentosa fruits. Taken together, these observations establish that A. austeni breeds in China, broaden knowledge of nest tree substrates and diet in this frontier population, and confirm that cooperative social systems persist at the species' northern range limit. Alongside recent records of Oriental Pied ( Anthracoceros albirostris ) and Great Hornbills ( Buceros bicornis ), these findings demonstrate that Shangyong sustains a multi‐species hornbill guild. Safeguarding cavity‐bearing trees, strengthening systematic monitoring, and enhancing transboundary cooperation with Laos are essential to secure these disturbance‐sensitive frugivores at the landscape scale. 白喉犀鸟 ( Anorrhinus austeni ) 是一种近危的食果鸟类, 其分布北缘延伸至中国云南南部。然而, 迄今为止, 国内尚未通过明确的巢址记录确认该物种的繁殖情况。2025年4月至5月, 我们在尚勇保护区勐满片区发现了两处白喉犀鸟的繁殖巢, 两个巢之间相距约3.5公里。通过观察, 我们发现这两个巢穴中, 正处于孵卵或育雏阶段的雌鸟均会将巢穴入口进行密封, 并由多只雄鸟共同负责喂食, 这一发现首次明确证实了白喉犀鸟在中国境内存在合作繁殖行为。其中一个巢穴位于高大的南酸枣 ( Choerospondias axillaris ) 树上, 雄鸟提供的食物包括假广子 ( Dysoxylum gotadhora ) 、假黄皮 ( D. binectariferum ) 的果实, 以及螳螂、蝉等动物性猎物；另一个巢穴位于溪谷旁的千果榄仁 ( Terminalia myriocarpa ) 树上, 食物则包括海红豆 ( Ormosia hosiei ) 、大肉实树 ( Pometia tomentosa ) 的果实。上述观察结果不仅证实了白喉犀鸟在中国境内存在繁殖种群, 丰富了该边境种群的巢树选择和食谱信息, 还确认了其合作繁殖体系在物种分布北缘依然稳定存在。结合近期在该区域记录到的冠斑犀鸟 ( Anthracoceros albirostris ) 与双角犀鸟 ( Buceros bicornis ), 更突显了尚勇保护区已成为这三种犀鸟的重要栖息地。作为犀鸟科物种在中国分布北缘的关键区域, 这种多物种共存的格局不仅直接反映了区域生物多样性的丰富, 也彰显了该区域在跨境生态廊道中的核心保护价值。因此, 保护拥有天然洞穴的高大树木、加强系统性监测, 以及深化与老挝的跨境合作, 成为在景观尺度上保护这些对干扰敏感的食果鸟类的关键措施。 In April and May 2025, two active Brown Hornbill ( Anorrhinus austeni ) nests were documented within the Mengman sector of the Shangyong Protected Area, Yunnan, approximately 3.5 km apart. Both involved sealed females provisioned by multiple males, establishing the first definitive breeding evidence of the species in China. The two nests differed in cavity tree species ( Choerospondias axillaris and Terminalia myriocarpa ) and in food items delivered ( Dysoxylum , Ormosia hosiei , Pometia tomentosa , plus arthropods), demonstrating reliance on large canopy cavities while tracking diverse fruit resources. Although the fate of both nests remains unknown due to the absence of continuous monitoring, these records confirm cooperative male attendance at the northern limit of the species’ range. Together with recent records of Oriental Pied and Great Hornbills, these findings highlight Shangyong as a stronghold of hornbill diversity at the Sino–Lao frontier, where strict protection has preserved habitat integrity. Safeguarding cavity‐bearing trees, enhancing systematic monitoring, and strengthening bilateral conservation with Laos are priorities to secure this disturbance‐sensitive guild. Two active nests confirm that Anorrhinus austeni breeds in China, establishing a resident population rather than sporadic visitors. Breeding relies on large cavity‐bearing trees and diverse fruiting species, underscoring the need to protect mature forest structure. The presence of multiple hornbill species demonstrates Shangyong's role as a guild‐level refuge, highlighting the value of strict reserve management. Cross‐border coordination with Laos is essential to mitigate hunting pressure and maintain canopy connectivity across the frontier. 2025年4月至5月, 研究团队在云南尚勇保护区勐满片区发现了两个繁殖活跃的白喉犀鸟巢穴, 巢与巢之间相距约3.5公里。白喉犀鸟的繁殖行为表现出独特的特点:雌鸟会将巢穴入口密封, 仅留下窄缝接收食物, 而多只雄鸟共同参与投喂食物。这是中国首次明确观察到白喉犀鸟的合作繁殖行为。 这两个巢穴位于不同的树种上, 分别是南酸枣树和千果榄仁树；雄鸟投喂的食物也有所不同, 除了假广子、假黄皮、海红豆和大肉实树等果实, 还包括螳螂、蝉等动物性食物。虽然由于缺乏持续监测, 目前无法确定两个巢穴的最终繁殖成功率, 但可以确认的是:在白喉犀鸟分布的北缘区域——中国云南, 该物种依然维持着合作繁殖的行为模式。 此外, 近期在该区域还记录到冠斑犀鸟与双角犀鸟的活动, 表明尚勇保护区已成为中老边境重要的犀鸟栖息地。该地区的保护措施为犀鸟提供了适宜的生存环境。未来, 需重点保护拥有天然树洞的高大树木, 加强对其繁殖动态的监测, 并推动与老挝的跨境保护合作, 为这些对干扰敏感的犀鸟提供长期的栖息保障。 两个繁殖巢的发现确认了白喉犀鸟在中国繁殖, 建立了稳定的种群, 而非偶尔迁入的个体。 白喉犀鸟繁殖依赖天然洞穴树木和多样化果树, 凸显保护成熟森林结构的重要性。 多种犀鸟共存展示了尚勇保护区作为物种群落庇护所的重要性, 突显了严格保护区管理的核心价值。 加强与老挝的跨境合作, 推动联合巡护以减轻狩猎压力, 加强森林保护以维持边境生态连通。

Gut microbiota plays an important role in animals and are considered microbial organs. Hornbill and toucan are birds of the same ecotypes with high appreciative value. In this study, we characterized and compared the gut microbiota of toco toucan (Ramphastos toco), great hornbill (Buceros bicornis) and wreathed hornbill (Rhyticeros undulatus) using 16S rRNA high‐throughput sequencing technology, and further discussed the influence of host bird genetics on its gut microbiota. We identified 10,847 operational taxonomic units (OTUs) from the hyper‐variable V4–V5 region, representing 14 phyla that were dominated by the Firmicutes, Proteobacteria, Cyanobacteria, Fusobacteria, Actinobacteria, and Bacteroidetes. Alpha diversity indices showed no significant difference among the three species (p > 0.1). However, great hornbill and toco toucan shared a high number of OTUs. Principal component analysis also revealed highly similar gut microbiotas between the two distant species. Therefore, environmental factors might dominate over host genetics in shaping the gut microbiotas of hornbill and toucan. Our study would contribute in elucidating adaptation of the hornbill and toucan to environmental change. We characterized and compared the gut microbiota in toco toucan (Ramphastos toco), great hornbill (Buceros bicornis), and wreathed hornbill (Rhyticeros undulatus) using 16S rRNA high‐throughput sequencing technology, and further discussed the influence of host genetics on bird gut microbiotas.

Hornbills living in tropical forests are predominantly frugivorous, but some species incorporate small animals into their diets, and bats have only been anecdotally recorded among their prey. However, it is not well known how they are captured and how often. We observed bushy‐crested hornbills (Anorrhinus galeritus) capturing wrinkle‐lipped free‐tailed bats (Mops plicatus) in flight as thousands of them emerged from a large cave‐roost in Bornean Malaysia. At least eight individuals successfully hunted flying bats by perching on dry branches hanging from the main entrance of the cave, using two tactics: (1) by jumping and making short flights until catching the flying bats (i.e., hawking), and (2) perching, waiting for bats that fly by at short distances, catching them with quick movements of the beak (i.e., snatching). This does not appear to be an anecdotal behavior, but rather one that has gone unnoticed until now. The number of hornbills hunting was greater than that of bat hawks (Machaeramphus alcinus), a diurnal raptor specialized in hunting bats. Further systematic monitoring of these and other diurnal avian predators is necessary to fully understand the pressure they exert on bats. We observed a group of bushy‐crested hornbills (Anorrhinus galeritus) surprisingly hunting bats as they fly out of a large roosting cave in Bornean Malaysia, but not when they are roosting inside the easily accessible cave. The frequency and skill with which they captured bats in flight suggest that this is not just anecdotal evidence, but rather an underreported, commonly used hunting strategy.

Oceanic islands, due to their evolutionary history and isolation, play a dual role of having high endemicity and being vulnerable to extinctions, with most known extinctions occurring on islands. Plant–animal interactions are particularly important on islands, as island systems generally have low redundancy and are more vulnerable to disruption either via extinction or by invasive species. Here, we examined the fruit removal and seed predation of a keystone palm, Caryota mitis, on Narcondam, a remote oceanic island. The island endemic Narcondam Hornbill (Rhyticeros narcondami) was the sole seed disperser of the palm (90 hours; N = 15 trees), with mean (± SE) visitation rate being 0.23 (± 0.06) individuals per hour and fruit removal rates of 3.5 (± 1.5; range: 0–16) fruits per visit, indicating a lack of redundancy in seed dispersal of the palm on this island. Whereas the invasive rodent, Rattus cf. tiomanicus, was the sole predator of palm seeds (N = 15 individual fruiting palms, 416 trap nights). Overall, 17.1% of the seeds placed (N = 375 seeds) were removed. Seeds placed under and away from the canopy, and at different densities (2 plots with 10 seeds each; 1 plot with 5 seeds, respectively), showed similar removal rates. This indicates density-independent seed predation and the lack of safe regeneration sites for Caryota mitis, with potential deleterious effects on subsequent stages of the ‘seed dispersal cycle’. Here, from a data-deficient site, we provide baseline information on the plant–frugivore interaction of a keystone palm and the potential impacts of an invasive rodent.

A \"visitor effect\" on zoo-housed species has been documented since the 1970s, with research focused on mammals (specifically primates). To broaden our understanding of the \"visitor effect\" in a non-mammal, we conducted a case study on a pair of hornbills, recording behavior and aviary use alongside of visitor and keeper presence. Temperature and humidity were significant predictors of visitor number, and temperature was a better predictor of hornbill exhibit use than visitor presence. Behavior was significantly affected by the presence of keepers and individual variation in behavior was noted too. Visitor number mediated any interest in a keeper by birds: high visitor number decreased a bird's interest in its keeper. Whilst only a case study on a pair of birds, our research shows that any \"visitor effect\" is heavily influenced by other environmental variables and that different categories of human (i.e., visitor, keeper) affect how zoo animals utilize their environment.

Despite the importance of seed dispersal for survival of plant species in fragmented landscapes, data on seed dispersal at landscape scales remain sparse. Effective seed dispersal among fragments determines recolonization and plant species persistence in such landscapes. We present the first large-scale (216-km2) direct estimates of realized seed dispersal of a high-value timber tree (Dysoxylum malabaricum) across an agro-forest landscape in the Western Ghats, India. Based upon an exhaustive inventory of adult trees and a sample of 488 seedlings all genotyped at 10 microsatellite loci, we estimated realized seed dispersal using parentage analysis and the neighbourhood model. Our estimates found that most realized seed dispersal was within 200 m, which is insufficient to effectively bridge the distances between forest patches. We conclude that using mobility of putative animal dispersers can be misleading when estimating tropical tree species vulnerability to habitat fragmentation. This raises serious concerns about the potential of many tropical trees to recolonize isolated forest patches where high-value tree species have already been removed.

While large avian frugivores are known to be key dispersers for large‐seeded tree species, their role in community‐wide plant‐disperser networks is still poorly known. Large avian frugivores are also among the most threatened due to anthropogenic impacts. We evaluated the role of large avian frugivores in a plant‐disperser community by (a) determining whether the plant‐disperser community was modular, with a distinct community of large frugivores (thereby highlighting their importance), (b) determining relative qualitative and quantitative roles played by large‐bodied frugivores vis‐à‐vis other frugivores and (c) determining impacts of large‐bodied frugivore loss on the plant‐disperser community. The study was carried out at a tropical forest site in north‐east India, which is part of the Eastern Himalaya Biodiversity Hotspot. We collected tree watch data (20:55 hr) from 46 tree species, which represented 85% of tree species that are predominantly bird‐dispersed in the area. We found that the plant‐disperser community was modular, with a distinct module of large‐seeded tree species and large frugivores. Intermediate‐sized frugivores such as barbets and bulbuls were the most connected, while large‐sized frugivores, such as hornbills and imperial pigeons, were moderately well connected. Qualitative and quantitative roles played by different dispersers varied across the gradient of frugivore body size. Hornbills, the largest avian frugivores, consumed a significantly greater number of fruits and swallowed larger proportions of fruits compared with other avian groups. In comparison with similar‐sized frugivores, imperial pigeons fed on larger‐sized fruits, highlighting their importance for dispersal of large‐seeded plants. Under simulated extinction scenarios, larger extinction cascades were not necessarily caused by larger frugivores; however, extinctions of certain large‐bodied frugivores (hornbills, imperial pigeons) caused extinction cascades. Integrating information from networks and seed dispersal effectiveness approaches enabled a better understanding of large frugivore role in a plant‐disperser community. While large‐bodied frugivores may not be playing a central role in plant‐disperser communities, they are crucial as seed dispersal service providers for large‐seeded plants. In conjunction with the reported local extinctions of large frugivores like hornbills from the south Asian region, this study’s findings highlight the irreplaceable quantitative and qualitative impacts that tropical plant communities are likely to experience in the future. This study integrates network and seed dispersal effectiveness approaches and demonstrates the importance of large avian frugivores (especially hornbills) in plant‐disperser communities in a poorly represented Asian region. These large frugivores, which are often targeted by hunting, play a critical role, especially in seed dispersal of large‐seeded plants.

The advent of new technologies in medical imaging and 3D printing in recent years has made customization of surgical tools and implants more accessible, revolutionizing many surgical fields. In many human diseases, these implants have led to superior surgical outcomes and greatly improved patients' quality of life. Thus, it is of great interest to apply these technologies to the treatment of animal diseases. In this study, we report the use of computed tomography (CT) and 3D printing for the treatment of a Great Hornbill at Jurong Bird Park that was diagnosed with squamous cell carcinoma of the casque. A 3D printed prosthesis that perfectly fitted the subject was implanted to replace its resected casque. The subject exhibited natural eating behaviour with no post-operative complications. Using this case as an example, the positive outcomes suggest a great potential in applying these technologies to the treatment of other wildlife diseases.

The microbiome of the uropygial gland and integuments where birds spread the uropygial secretion may play crucial roles for their hosts, but it has been poorly studied, especially in wild species. Exploring bacterial communities associated with the uropygial secretion of birds is particularly interesting in species under strong selection pressures due to pathogenic infection. Here, by high‐throughput 16S rRNA amplicon sequencing, we characterized and compared the bacterial communities of the uropygial gland surface of three African hornbill species (Family Bucerotidae), as well as the bill and feathers of females from two of these species and the nestlings of the other one. In accordance with previous knowledge of avian microbiomes, we expected to find differences associated with species identity, age and the sampled integument. Overall, we found that: 1) the microbiome was similar among species, 2) but there were slight differences associated with the sampled body regions. Moreover, 3) we observed no consistent variation in the microbiota with age, and 4) females and nestlings sharing a nest harboured more similar gland surface microbiota compared to females and nestlings that did not share a nest. These species often reuse nest cavities, sealing them with a plug made from diverse material. Once sealed, they remain enclosed in the nest for a long period. This behaviour opens the possibility that the nest environment is key shaping the microbiota of these species and might serve as a reservoir of the sampled bacterial communities. Moreover, behavioural mechanisms such as preening may contribute to the transmission of bacteria from the uropygial gland to other body regions, enhancing bacterial similarities. This study contributes to our understanding of the role of the nest environment in structuring bacterial communities in wild birds and provides the first thorough characterization of the microbiome inhabiting different body integuments of southern African hornbills.