Grey-faced Buzzard Butastur Indicus Research Articles

Raptor migration at Guantouling, south-west China: phenology, weather influence and persecution pressure

Summary South-west China, particularly between the Himalayas and the Beibu Gulf, constitutes an important corridor for migratory raptors along the East-Asian continental flyway. However, a lack of ornithological assessment and the common practice of illegal hunting in this region emphasize the need for research and conservation actions. To investigate the ecology of migration and scale of persecution, we launched one of the first citizen-science projects in mainland China to record southward-migrating raptors and hunting gunshots from 2015 to 2019 on Guantouling, a well-known raptor site in South-west China. A total of 42,891 raptors were recorded, belonging to 30 diurnal raptor species. Grey-faced Buzzard Butastur indicus, Oriental Honey Buzzard Pernis ptilorhynchus and Amur Falcon Falco amurensis were the three most abundant species recorded. The bulk of Grey-faced Buzzard and Amur Falcon migrated through Guantouling from mid-October till early November, while Oriental Honey Buzzard migrated throughout October and early November. Precipitation slowed down migration significantly while increasing cloud cover was favoured by the three most abundant species. We found hunting mostly occurred in the afternoon, coinciding with an increasing number of Oriental Honey Buzzard, which may become a major victim of hunting. It is thus suggested to prioritize peak raptor migration period for law enforcement actions, especially on cloudy days and after passage of cold fronts, when Oriental Honey Buzzards and other species are likely to migrate. The annual counting scheme on Guantouling is not only an ecological survey, but also an effective way of engaging the public to counter raptor persecution.

Raptor migration in an oceanic flyway: wind and geography shape the migratory route of grey-faced buzzards in East Asia.

Flapping flight is relatively costly for soaring birds such as raptors. To avoid costly flight, migrating raptors generally avoid flying over water. As a result, all but one of the global raptor migration flyways are largely over land. The East Asian oceanic flyway for raptors is the exception. Raptor species using this flyway migrate by island-hopping, flying over open ocean for distances of up to 300 km between islands. We used satellite telemetry data for grey-faced buzzards Butastur indicus, a species that dominates the southern part of the flyway, to investigate the geographical and atmospheric factors responsible for the suitability of this flyway for raptor migration. Using a combination of least-cost path analysis and a step selection function, we found that the occurrence of numerous islands and also suitable wind support along the oceanic flyway are responsible for route selection in grey-faced buzzards. These results confirm the role of islands, but also wind, in shaping the East Asian oceanic flyway of long-distance raptor migration.

Porrocaecum parvum n. sp. and P. reticulatum (Linstow, 1899) (Nematoda: Ascaridoidea) from birds in China.

Porrocaecum parvum n. sp. is described from the grey-faced buzzard Butastur indicus (Gmelin) (Accipitriformes: Accipitridae) in China. The new species differs from its congeners in having well-developed cervical alae, small interlabia and very short intestinal caecum (0.34 mm long, representing 11.9% of oesophageal length) and in the number and arrangement of the caudal papillae (29 pairs in total, arranged as follows: 21 pairs precloacal, single double pair paracloacal and seven pairs postcloacal) and in the morphology of the male tail. In addition, Porrocaecum reticulatum (Linstow, 1899), collected from the purple heron Ardea purpurea L., the grey heron A. cinerea L. and the little egret Egretta garzetta (L.) (Pelecaniformes: Ardeidae) in China, was also studied using light and, for the first time, scanning electron microscopy. Previously unreported and erroneous morphological features of taxonomic significance are revealed, including the presence of narrow cervical alae, single pair of small, submedial pores and single, short medial ditch on each lip, interlabia with very pointed anterior prolongation, single medio-ventral precloacal papilla on anterior cloacal lip and double paracloacal papillae slightly posterior to cloaca.

Route and site fidelity of two migratory raptors: Grey-faced Buzzards Butastur indicus and Honey-buzzards Pernis apivorus

In order to examine fidelity to migration route, breeding, wintering, and stopover sites, we analyzed the migration of two adult Grey-faced Buzzards Butastur indicus and an adult Honey-buzzard Pernis apivorus that were satellite-tracked in East Asia for more than two migration seasons. The Grey-faced Buzzards showed a high degree of route fidelity across seasons and years. On the other hand, the migration routes of the Honey-buzzard were distinctly different between fall and spring seasons, whereas, within each season they were roughly similar between years. All three raptors were strictly faithful to their breeding and wintering sites. They also showed fidelity to several stopover sites in which the raptors stayed for relatively long periods to replenish energy. Our findings have important implications for the conservation of the migratory raptors.

What landscape elements are correlated with the distribution of wintering Grey-faced Buzzards Butastur indicus in the Sakishima Islands, southwestern Japan?

The Grey-faced Buzzard (Butastur indicus) is a typical migratory raptor species in East Asia, and has suffered a population decline recently. In southern Japan, the wintering buzzards are widely distributed to the Sakishima Islands. The mainly human activity on these islands is agriculture, and the natural environments are fragmented by such exploitative land-use that produces a characteristic landscape pattern. In this study, we describe the distribution pattern and habitat selection of the buzzards wintering in the Sakishima Islands, and focus on landscape elements in order to give a basic reference for further conservation study. Ten islands were investigated during January to March 2005. We used the generalized linear mixed model (GLMM) on a set of landscape elements to model buzzard distribution in the 1×1 km grid cell within each island, and studied the relationships between the numbers of buzzard and landscape elements among islands by using the generalized linear model (GLM). The results were similar on two spatial scales, and they both suggested that the area of farmlands (sugar cane, pasture, and rice paddy), and the perimeter of forests have significant correlation with the distribution and the numbers of the wintering buzzards. Different from breeding sites where distribution was limited by critical nest resource, distribution of Grey-faced Buzzards in wintering sites was simply related to foraging habitats. We suggest that further study should focus on measuring quantitatively the relationships of different farmland types with buzzard distributions in order to make more realistic predictions about distribution when habitat is lost or shifted from one category to another.

Route and site fidelity of two migratory raptors: Grey-faced Buzzards Butastur indicus and Honey-buzzards Pernis apivorus

In order to examine fidelity to migration route, breeding, wintering, and stopover sites, we analyzed the migration of two adult Grey-faced Buzzards Butastur indicus and an adult Honey-buzzard Pernis apivorus that were satellite-tracked in East Asia for more than two migration seasons. The Grey-faced Buzzards showed a high degree of route fidelity across seasons and years. On the other hand, the migration routes of the Honey-buzzard were distinctly different between fall and spring seasons, whereas, within each season they were roughly similar between years. All three raptors were strictly faithful to their breeding and wintering sites. They also showed fidelity to several stopover sites in which the raptors stayed for relatively long periods to replenish energy. Our findings have important implications for the conservation of the migratory raptors.

What landscape elements are correlated with the distribution of wintering Grey-faced Buzzards Butastur indicus in the Sakishima Islands, southwestern Japan?

What landscape elements are correlated with the distribution of wintering Grey-faced Buzzards Butastur indicus in the Sakishima Islands, southwestern Japan?

Population Trend Estimation of Three Threatened Bird Species in Japanese Rural Forests: the Japanese Night Heron Gorsachius goisagi, Goshawk Accipiter gentilis and Grey-faced Buzzard Butastur indicus

The population trends of the Japanese Night Heron Gorsachius goisagi, the Goshawk Accipiter gentilis and the Grey-faced Buzzard Butastur indicus were estimated based on records of the number of individuals kept in Japanese zoos since the 1960s. Because no special effort is made to collect these species, and because they seldom breed in captivity, their population changes in zoos were assumed to reflect that of the wild populations. In order to reinforce the zoo data, we collected local records of the population trends of these three species in Niigata Prefecture, Tochigi Prefecture, Cape Irago of Aichi Prefecture and the Miyako Islands of Okinawa Prefecture. The results indicated that at all investigated localities, except Tochigi Prefecture, the Japanese Night Heron and the Grey-faced Buzzard had decreased in numbers since the 1960s, whereas the Goshawk had increased in number nationwide. There is, however, a possibility that the increase in the Goshawk population is an overestimation, and it is necessary to investigate its wild population trend in detail. The most likely cause of the declines of the Japanese Night Heron and the Grey-faced Buzzard is habitat degradation, both in quality and in quantity. To date, these two species have not been the targets of any concerted conservation effort, but they must henceforth be accorded this status.

Nest Site Characteristics of the Grey-faced Buzzard Butastur indicus

The habitat of 52 nest sites of the Grey-faced Buzzard Butastur indicus was examined in a low mountain region of central Japan. Most (90-100%)of nest trees were within 600 m of a stream and paddy field on the valley bottom. Therefore, the availability of wet areas which offer food (e.g.frogs and snakes) may be an important factor affecting the nest site selection. Eighty-eight percent of nest trees were on the middle or lower portions of steep slopes, irrespective of the direction of the slope aspect.Sixty-nine percent of nest trees were either trees at the forest edge or prominent trees within the forest. So, the accessibility for birds approaching the nest may also be an important factor.

Predation on Nymphs of the Evening Cicada Tanna japonensis by the Grey-faced Buzzard Butastur indicus

At least 11 final instar nymphs of the evening cicada Tanna japonensis were found in the crop of a dead Grey-faced Buzzard Butastur indicus collected from Ogane, Minaminasu-machi, Nasu-gun, Tochigi Prefecture on September 13, 1987. This is the first record of the predation on cicadid nymphs by B. indicus.