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The present study deals with the observation of avifauna in the aquatic habitat and their adjoining areas of Ramnagar, Uttarakhand, India. The present study was carried out from January 2020 to December 2020. We have recorded a total of 145 avian species belonging to the 54 families during the study period. Among this, a total of 113 residents and 32 winter visitor species were identified. The percentage of resident and winter visitor avian species was 78.08% and 21.91%. During the study period, we also reported the four avian species viz., River Lapwing, River tern, Great Hornbill, and Alexandrine Parakeet are under the Near Threatened (NT) category and one species, namely Red-headed vulture is critically endangered according to IUCN Red data book. Thus, the findings of this study suggest that the selected study area has avifauna diversity of utmost importance which should be conserved by implementing specific strategies.

Loss of mature tropical forests to agricultural expansion often creates landscapes with forest fragments embedded within a matrix of human-modified habitats and land uses. Such habitat fragmentation may be detrimental to species with specialized habitat and foraging requirements and their ability to persist in such landscapes may depend on their adaptability to habitat modification. Great Hornbills Buceros bicornis, among the largest birds in Asian tropical rainforests, depend on large trees for nesting and a diverse array of patchily distributed fruiting trees. In the human-modified landscape of the Anamalai Hills, India, we compared the breeding biology and nesting behaviour of Great Hornbills in contiguous rainforest (N=3 nests) and in modified habitat consisting of coffee plantations and rainforest fragments (N=5 nests). The nesting cycle of seven of the eight nests monitored varied between 114 and 130 days. Nest provisioning behaviour was similar in contiguous forest and modified habitat in terms of visitation and food delivery rates, but visitation tended to be higher and food delivery rate lower during the nestling phase than during incubation. As expected, tree density and native food plant diversity were lower in modified habitat than in continuous forest. The diversity of food provisioned was lower in modified habitat with a 57.5% dietary overlap with contiguous forest. Hornbills in the modified habitat of coffee plantations used non-native tree species for nesting and foraging, indicating their adaptability to modified landscapes.

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.

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.

Two major bile acids were isolated from the gallbladder bile of two hornbill species from the Bucerotidae family of the avian order Bucerotiformes Buceros bicornis (great hornbill) and Penelopides panini (Visayan tarictic hornbill). Their structures were determined to be 3α,7α,24-dihydroxy-5β-cholestan-27-oic acid and its 12α-hydroxy derivative, 3α,7α,12α,24-tetrahydroxy-5β-cholestan-27-oic acid (varanic acid, VA), both present in bile as their corresponding taurine amidates. The four diastereomers of varanic acid were synthesized and their assigned structures were confirmed by X-ray crystallographic analysis. VA and its 12-deoxy derivative were found to have a (24R,25S)-configuration. 13 additional hornbill species were also analyzed by HPLC and showed similar bile acid patterns to B. bicornis and P. panini. The previous stereochemical assignment for (24R,25S)-VA isolated from the bile of varanid lizards and the Gila monster should now be revised to the (24S,25S)-configuration.

The fruit-tracking hypothesis predicts a positive association between frugivores and fruit abundance over space and time. We documented hornbill diets and examined the relationship between fruit abundance and abundance of three hornbill species (Buceros bicornis, Rhyticeros undulatus and Aceros nipalensis) in the Eastern Himalaya from 2009–2012. The study was carried out at three scales: at the largest scale of the study area (15 km2), at the intermediate scale – eight 3-ha patches within the study area and at the smallest scale of individual fruiting trees. Ninety-one per cent of the 64 foraging sightings of the great hornbill were on figs while more than 50% of the foraging sightings of the wreathed (83) and rufous-necked hornbills (87) were on non-fig fruits. At the largest scale, wreathed hornbill abundance and ripe fruit abundance peaked in the non-breeding season. At the intermediate scale, wreathed hornbill abundance was positively associated with non-fig fruit availability while rufous-necked hornbill abundance was negatively associated with non-fig fruit availability. At the smallest scale, great and rufous-necked hornbill abundances were correlated with fig and non-fig fruit crop sizes, respectively. The three hornbill species track fruit availability at different scales based on diet, which has implications for their role in seed dispersal.

Great hornbills (Buceros bicornis) are a long-lived, monogamous species that forms strong pair-bonds, and mate compatibility is thought to be important for successful reproduction. Within AZA, great hornbills are listed as a red SSP. The population consists of a limited number of individuals that do not breed reliably, and improving reproduction is a top priority for the Coraciiformes TAG. To better understand mating behavior and evaluate mate compatibility, this study documented the behavior of pairs of great hornbills during and immediately after courtship. Using live observations, the study followed one female, an experienced and successful breeder, as she was paired with four successive males over 11 breeding seasons. Initially, males frequently vocalized, investigated the nest, and approached the female. As the female spent more time in the nest, these behaviors were replaced by regurgitation and food offering. The female was most often observed plastering and vocalizing. Behavioral differences between successful and unsuccessful pairs, possibly indicative of pair compatibility, included rates of approaching, billing, and biting. Numerous behaviors occurred more frequently during years that a chick hatched, including pseudoregurgitation, regurgitation, offering food items, and nest investigation. Males also spent more time in proximity to both the female and the nest during years that a chick hatched. Together, these results suggest that the amount of time pairs spend in proximity, the amount of time a male spends near the nest, and the frequency of certain behaviors may help evaluate compatibility and the likelihood of successful reproduction for pairs of great hornbills.

The loss of tropical forests and associated biodiversity is a global concern. Conservation efforts in tropical countries such as India have mostly focused on state-administered protected areas despite the existence of vast tracts of forest outside these areas. We studied hornbills (Bucerotidae), an ecologically important vertebrate group and a flagship for tropical forest conservation, to assess the importance of forests outside protected areas in Arunachal Pradesh, north-east India. We conducted a state-wide survey to record encounters with hornbills in seven protected areas, six state-managed reserved forests and six community-managed unclassed forests. We estimated the density of hornbills in one protected area, four reserved forests and two unclassed forests in eastern Arunachal Pradesh. The state-wide survey showed that the mean rate of encounter of rufous-necked hornbills Aceros nipalensis was four times higher in protected areas than in reserved forests and 22 times higher in protected areas than in unclassed forests. The mean rate of encounter of wreathed hornbills Rhyticeros undulatus was twice as high in protected areas as in reserved forests and eight times higher in protected areas than in unclassed forests. The densities of rufous-necked hornbill were higher inside protected areas, whereas the densities of great hornbill Buceros bicornis and wreathed hornbill were similar inside and outside protected areas. Key informant surveys revealed possible extirpation of some hornbill species at sites in two protected areas and three unclassed forests. These results highlight a paradoxical situation where individual populations of hornbills are being lost even in some legally protected habitat, whereas they continue to persist over most of the landscape. Better protection within protected areas and creative community-based conservation efforts elsewhere are necessary to maintain hornbill populations in this biodiversity-rich region.

Anecdotal evidence suggests the endangered Great Hornbill (Buceros bicornis) needs mature, large old-growth trees for nesting. We tested this hypothesis by measuring vegetation characteristics at 24 nest sites in southern India and compared these data with that obtained from equal numbers of unused forest sites. Characteristics significantly different from surrounding forest at hornbill nesting sites were several properties related to size of trees. The nesting habitat characteristics of the species stress the importance of mature forests with emergent trees for nests of the Great Hornbill. Trees used by Great Hornbills for nests, compared to unused trees, averaged 18.5 m taller, 0.85 m greater in diameter, and emerged more above the forest canopy by 12.7 m. Canopy height, canopy cover, and number of large trees >75 cm DBH were greater at nest sites than at unused sites by 5.79 m, 3.15%, and 1.63 trees, respectively.

Ranges of individual males of three hornbill species were determined by radio telemetry during the breeding and non-breeding seasons in Khao Yai National Park, Thailand. Two Great Hornbills Buceros bicornis and two Brown Hornbills Ptilolaemus tickelli were studied in both 1988 and 1989, and two Wreathed Hornbills Rhyticeros undulatus were studied in 1989, 1990 and 1991. In the breeding season, the home range of the Great Hornbill was 3.7 km2, similar to that of the Brown Hornbill (4.3 km2), while the Wreathed Hornbill occupied the largest home range (10.0 km2). In the non-breeding season, the range size of the Wreathed Hornbill (28.0 km2) was greater than that of the Great Hornbill (14.7 km2). Differences in range sizes of different species may be related to differences in diet and breeding strategy. Ranges overlapped within and between the species, and this has implications for the estimation of the minimum area required for the conservation of hornbills within the Khao Yai National Park.

The literature pertaining to nesting of the Great Hornbill (Buceros bicornis) is ambiguous regarding whether the birds use mud as plaster material to seal their nest cavity entrances. We studied the breeding biology of the species in southern India and detected no evidence of mud delivery or usage in 183 hrs of nest observations. Chemical analysis of plaster material showed that it was composed exclusively of fecal material and not mud.

Asian hornbills are primarily frugivorous. We studied the characteristics of fruits consumed by four sympatric hornbill species in Thailand: Great Hornbill (Buceros bicornis), Wreathed Hornbill (Aceros undulatus), Austin's Brown Hornbill (Anorrhinus austeni) and Oriental Pied Hornbill (Anthracoceros albirostris). We compared the frequency of distribution of 11 variables for all fruit species collected in the study area (n = 259) and fruit species consumed by hornbills (n = 73). Our analysis revealed that fruits consumed by hornbills are: (1) large, (2) easily accessible within the canopy, (3) red, purple or black and (4) dehiscent or indehiscent with a thin husk. The range of fruit sizes eaten by hornbills in our study is comparable to that reported from other sites in Southeast Asia and Africa. The large gape width of hornbills enables them to consume large fruits that small frugivores would find difficult to consume.

Internal security problems from the 1960s up until 1998 prevented any fieldwork in Cambodia. Since then, the situation has improved greatly and the Royal Government of Cambodia, in collaboration with international conservation NGOs, has been conducting general biological surveys across the country. Survey reports were used to investigate current occurrence of hornbills. Historically, three hornbill species — Great Hornbill Buceros bicornis, Wreathed Hornbill Aceros undulatus and Oriental Pied Hornbill Anthracoceros albirostris — were known from Cambodia. Recent surveys show that populations of Great and Wreathed Hornbills have declined significantly since the 1960s, while Oriental Pied is still common. A fourth hornbill species, Brown Hornbill Anorrhinus tickelli, was reported in 1998 in Kirirom National Park spanning the border of Koh Kong and Kompong Speu provinces in south-west Cambodia. Conservation priorities and priorities for future surveys are being developed.

Nest-site selection by the sympatric Great Hornbill Buceros bicornis, Wreathed Hornbill Aceros undulatus and Oriental Pied Hornbill Anthracoceros albirostris was investigated in a lowland tropical forest in Arunachal Pradesh, north-east India during 1997–2000. Information on two nests of Rufous-necked Hornbill Aceros nipalensis in higher-elevation forests is also presented. All species nested in live trees of three tree genera, 83% (n = 36) in Tetrameles nudiflora, an emergent deciduous softwood, relatively common in lowland foothill forests. No difference was recorded in nest-tree species or nesting habitats of sympatric hornbills, but there were a few differences in structural characteristics of nest-trees. Cavity size was the main variable separating the three species. Great Hornbills used larger cavities while Oriental Pied Hornbills used smaller cavities closer to riverine areas. Nesting was attempted at 64% of known sites and successful fledging of chicks was 80% overall (n = 72 nests, pooled over 4 years). Nest-trees in disturbed habitats near human habitation were used but were often abandoned or unsuccessful and 50% of all nest-trees were inactive by the end of the study. Potential large nest-trees had a density of 5.9/ha, that of the two most used species was 1.3/ha, and minimum nest densities of all three species was about 1 pair/km2. Interference competition for nest-sites was not observed, despite similarity in nest-tree characteristics, low nest density and high loss of nest-trees. Nest-site availability may naturally limit hornbill populations in the area, and additional loss of nesting habitat to human activities may exacerbate limited availability of breeding sites.

Hornbills are omnivorous and the breeding male delivers all food required by the nest-confined female and chicks. The contributions of different food types, in terms of breeding nutrition, have not previously been documented. In Khao Yai Na- tional Park, Thailand, we sampled the identity and number of food items delivered daily to the nest, during each week of the nesting cycle, by two small and two large sympatric species of hornbills. We then recorded the mass and estimated the nutrient content of each food type from analyses of protein, fat, carbohydrate, calcium, and energy. The overall pattern of nutrient delivery during the nesting cycle was the same for each of the four hornbill species, and was related to sequential demands for egg, feather, and chick development. The two larger species delivered mainly carbohy- drates (Great Buceros bicornis 50%, Wreathed Aceros undulatus 57%) and less fat and protein. The smallest, Oriental Pied Hornbill Anthracoceros albirostris, also de- livered mostly carbohydrate (45%), but the small White-throated Brown Hornbill An- orrhinus austeni delivered equivalent proportions of protein (32%), fat (30%), and carbohydrate (37%). Comparison of the incubation and nestling phases showed that more protein was delivered during the nestling phase for all species, except for Great Hornbill where the compression of egg production, incubation, and molt had to be completed by midway through the nestling phase and so high levels of fat and protein were delivered during incubation. We confirmed that fruits are an important source of all nutrients, especially fat, for all four hornbill species, but suggest that delivery of animal protein may be linked, in some way, to breeding success. Oriental Pied Horn- bill broods, that received protein at about 1.05% of brood mass per day, had the high- est breeding success (96%) whereas Wreathed Hornbills received only 0.57% protein and had only 67% success, while the other two species delivered intermediate amounts of protein and had intermediate breeding success.

The distribution and abundance patterns of Malabar Grey Hornbill Ocyceros griseus and Great Hornbill Buceros bicornis were studied in one undisturbed and one heavily altered rainforest landscape in the southern Western Ghats, India. The Agasthyamalai hills (Kalakad-Mundanthurai Tiger Reserve, KMTR) contained over 400 km2 of continuous rainforest, whereas the Anamalai hills (now Indira Gandhi Wildlife Sanctuary, IGWS) contained fragments of rainforest in a matrix of tea and coffee plantations. A comparison of point-count and line transect census techniques for Malabar Grey Hornbill at one site indicated much higher density estimates in point-counts (118.4/km2) than in line transects (51.5/km2), probably due to cumulative count over time in the former technique. Although line transects appeared more suitable for long-term monitoring of hornbill populations, point-counts may be useful for large-scale surveys, especially where forests are fragmented and terrain is unsuitable for line transects. A standard fixed radius point-count method was used to sample different altitude zones (600–1,500 m) in the undisturbed site (342 point-counts) and fragments ranging in size from 0.5 to 2,500 ha in the Anamalais (389 point-counts). In the fragmented landscape, Malabar Grey Hornbill was found in higher altitudes than in KMTR, extending to nearly all the disturbed fragments at mid-elevations (1,000–1,200 m). Great Hornbill persisted in the fragmented landscape using all three large fragments (> 200 ha). It was also recorded in four of five medium-sized fragments (25–200 ha) and one of five small fragments (< 25 ha), which was adjacent to shade coffee plantations. Abundance of Malabar Grey Hornbill declined with altitude and increased with food-tree species richness. Great Hornbill abundance increased with food-tree species richness, suggesting that maintenance of high diversity of hornbill food species in fragments is important for their persistence. It is likely that the smaller and less specialized Malabar Grey Hornbill will survive in disturbed and fragmented forest landscapes, while Great Hornbill is more vulnerable to habitat alteration. Protection and restoration of rainforest fragments and food-tree resources, besides protection of existing large fragments, will aid the conservation of hornbills in the region.

The diet and food resource partitioning of three sympatric hornbills (Great Hornbill Buceros bicornis, Wreathed Hornbill Aceros undulatus, and Oriental Pied Hornbill Anthracoceros albirostris) during the nonbreeding season were studied relative to fruit availability in a foothill semievergreen forest of Arunachal Pradesh, northeast India. Hornbills fed on fruits of 49 plant species that comprised over 95 percent of their diet. Hornbill species partitioned food resources by varying the relative contribution of figs and non-fig fruits in the diet. Similarity in non-fig fruit diet was low. Ten species contributed to over 90 percent of the non-fig diet. The availability of non-fig fruits was much lower in the nonbreeding season than in the breeding season; however, despite lower fruit availability during the nonbreeding season, hornbills had a wide diet breadth and indirect evidence suggests that Wreathed Hornbills foraged widely in this season for fruit. Great Hornbills relied more on figs that were available year-round. The diverse diet breadth that included rare and patchy fruit resources underscores the importance of conserving large forest tracts for hornbills.

The population of great hornbills (Buceros bicornis) in the United States is rapidly aging, and captive breeding efforts have not met population managers’ expectations for a sustainable captive group. Little is known about the reproductive physiology of these birds. This study reports the first data on the reproductive endocrinology of the great hornbill. The hormone profiles of the only pair of these birds that hatched a chick in the 1999–2000 breeding season are compared to the profiles of six other pairs of hornbills, from different institutions in the United States, that did not reproduce successfully that season. The study investigates the estradiol, corticosterone, and testosterone profiles of these seven pairs of birds, establishing a base of knowledge from which endocrine data may be used to improve the success of captive breeding programs. The estradiol profiles from this study indicate a difference in hormonal patterns between laying and non-laying female great hornbills. Egg-laying females had significantly higher estradiol concentrations during the breeding season than the non-laying females (Po0.003). Testosterone concentrations of the males were not significantly different between the mates of egg-laying and non-egg-laying females. The corticosterone concentrations tended to be lower in the females that laid eggs vs. the non-egg-laying group. The males of the egg-laying pairs showed a significantly lower (Po0.036) corticosterone concentration than the non-egg-laying male pairs. This, combined with the extremely low corticosterone levels (compared to the other birds in the study) of the pair of hornbills that hatched a chick in the 1999–2000 breeding season, suggests that adrenal activity may play a role in the reproductive failure of some captive great hornbills. Zoo Biol 22:135–145, 2003. � c 2003 Wiley-Liss, Inc.

A 33-year-old male great hornbill (Buceros bicornis) presented with a roughened fis- sured rostral casque. Physical examination revealed a softened rostral casque and diagnostic tests indicated a squamous cell carcinoma. A course of photodynamic therapy was begun in which cytotoxic oxygen radicals were generated to destroy tumor cells. Two courses of photodynamic therapy reduced the size and spread of the tumor initially but failed to eliminate the cancer. Upon physical deterioration and progression of the neoplasia, the bird was euthanized.

Thirteen polymorphic microsatellite markers were isolated and characterized from the great hornbill, Buceros bicornis. In analyses of 20 individuals, the numbers of alleles per locus varied from two to 11. The expected and observed heterozygosities ranged from 0.22 to 0.88 and from 0.20 to 1.00, respectively. The mean polymorphic information content was 0.62. Among these, three loci deviated from the Hardy-Weinberg equilibrium. However, no significant genotypic disequilibrium was detected between any pair of loci. These microsatellite markers are useful for the population genetic study of the great hornbill.

Ranganathan et al. (1) conclude that arecanut plantations in south India are useful for bird conservation based on a comparison of species richness with intact forest. Consideration of abundance data might provide different insights. The supporting information (SI) shows that typical forest species such as Irena puella, Hypothymis azurea, and Alcippe poioicephala were present in both forests and arecanut plantations but were detected 6, 3, and 8 times, respectively, more often in forests. In my experience in the Western Ghats, I find that most forest bird species, including Great Hornbill, are occasionally found even in bird-unfriendly land uses such as tea plantations, possibly during movement between forest patches; but they are detected much more often in intact forests. Information on population densities and breeding success of species are required before we can decide on the suitability of a particular land use for conservation.

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