Butastur Indicus Research Articles

Field validation of effects of species and flock size on echoes in avian radar surveys

Radar is a powerful technology for surveys of avian movements. Validating the accuracy of radar detection is essential when establishing quantitative criteria for tracking bird trajectories and counting bird flocks. This study clarifies the positional and biological factors influencing the probability of detection (POD) and echo size on X-band marine radar. The bird trajectory for validation was obtained by ornithodolite at the same time as the radar scan. Distance was found to have a negative effect on POD and echo size, while elevation angle positively affected POD. Body mass and flock size positively affected POD and echo size. In predicting detection performance, the survey distance required to achieve 50% POD was 750 m or less for Grey-faced Buzzard, the lightest target species, but up to 1800 m for a pair of Bewick’s Swan. Our study provides survey and analysis procedures that allow for efficient validation using ornithodolites. Then, we identify the range settings that should be considered for target species and contribute to establishing criteria for quantitative radar bird surveys.

Night Landing of Grey-Faced Buzzards (Butastur indicus) on a Ship During Migration

Night Landing of Grey-Faced Buzzards (Butastur indicus) on a Ship During Migration

Spring Migration of Diurnal Raptors in Northern Luzon, Philippines, along the Oceanic Flyway in 2015 and 2016

ABSTRACT Little is known about the spatiotemporal distribution of raptor migration in the Philippines. Located at the center of the East-Asian Oceanic Flyway, the archipelago is an ideal site to conduct raptor migration surveys. To augment knowledge of raptor migration in the region, we identified two watch sites and conducted surveys in spring 2015 and 2016 to determine the timing and abundance of raptors migrating through northern Luzon. We recorded 62,088 raptors in 2015 at Pagudpud, Ilocos Norte, over 34 survey d, and 36,443 raptors in 2016 at Sanchez Mira, Cagayan over 25 d. Grey-faced Buzzards (Butastur indicus) and Chinese Sparrowhawks (Accipiter soloensis) dominated the counts. The relatively low abundance of migrants compared to other sites along the flyway, and variation between our two count sites/years partly reflected the influence of variable and relatively limited survey periods and effort. Despite this limitation, we gained important insights about migration routes and timing in this part of the East-Asian Oceanic Flyway. Preliminary data on migration patterns are important to understand migration strategies. With additional data, we can build models of route and habitat suitability and use them for species and habitat conservation.

Migratory Daily Departure Times of Chinese Sparrowhawks (Accipiter soloensis) and Gray-Faced Buzzards (Butastur indicus) in Taiwan

ABSTRACT The strategies that migratory raptors adopt during migration reveal their long-term adaptations to different environments along their migration routes and of their stopover sites. We recorded the daily departure time of Chinese Sparrowhawks (Accipiter soloensis) and Gray-faced Buzzards (Butastur indicus) during their southward migration in autumn 2019 at Kenting National Park, southern Taiwan, and 2020 in Yushan National Park, central Taiwan. At both watchsites, Gray-faced Buzzards started their migration journey about 1 hr earlier than Chinese Sparrowhawks. After adjusting for the local sunrise time, the first daily appearance time of Gray-faced Buzzards (–2.5 ± 9.3 min) was significantly earlier than that of Chinese Sparrowhawks (47.0 ± 29.3 min) by about 50 min at Kenting National Park. Though they initiated migration later in morning at montane stopover sites in Yushan National Park, the same trend was observed and with even greater difference, about 70 min. These results indicate that these two species migrate in different daily periods and suggest that Chinese Sparrowhawks might choose to exploit stronger thermal uplifts in September before leaving the island, as they started migration later in the morning. In contrast, Gray-faced Buzzards, a species more dependent on soaring-gliding flight, set off earlier in the day, probably to take advantage of stronger northeastern tailwinds that begin in October. We conclude that the prevailing monthly wind conditions, particularly influenced by the northeast monsoons, shape the different diurnal migration times of these two raptors migrating along the East-Asian Oceanic Flyway.

Historical – Biographical Study on Grey-Faced Buzzard (Butastur indicus) from the Perspectives of the Old Folks in Sanchez Mira , Cagayan, Philippines

Background/Objectives: Grey-faced buzzard (Butastur indicus), locally known as Sawi, is a migratory raptor that pauses for stopover in the country during its trans–equatorial flight across the Pacific. Recent reports showed a gradual decline in the number of bird species as they transverse the Philippine archipelago especially in the northern part of Luzon. In this study, the researchers took into account the biographical information of the Greyface buzzard and its historical significance to the people. Methods/Statistical analysis: The study employed the Historical – Biographical research design and selected informants for interview through purposive sampling technique. Interview protocol was the main tool in gathering the needed data. The study covered the barangays frequented by the Grey-faced buzzard (Butastur indicus) in the municipality of Sanchez Mira, Cagayan, Philippines. In particular, these are barangay Callungan, Pukel, Santiago, Marzan, and Dacal, Cagayan, Philippines. There were 80 informants included in the data collection process. Mean and percentage were applied in dealing with the statistical computation of data gathered. Findings: Results showed that the old folks from Sanchez Mira, Cagayan, Philippines know significant biographical and historical information about the Grey-faced buzzard (Butastur indicus) and the most common of which is that there was no distinct difference in the color of a male and female Grey-faced buzzard. The Grey-faced buzzards usually inhabit the dense forest areas in the municipality consuming insects living on trees as their main diet. It was commonly observed by the old folks that these raptors usually arrive in Sanchez Mira, Cagayan, Philippines during the months of March and April, and this had been consistent every year hence making Sanchez Mira as one of their frequent stopover sites during their migration periods. Different contributions of the birds such as its role in the pest control management and its potential to attract tourists were highlighted. A gradual decline in the cases of hunting were observed by the interviewees. Novelty/Applications: The locale of the study makes it unique since historical – biographical information of grey-faced buzzard in this area is under studied. Keywords: Greyfaced buzzard; historical; biographical; conservation; Philippines

The significance of region-specific habitat models as revealed by habitat shifts of grey-faced buzzard in response to different agricultural schedules

To determine large scales habitat suitability for focal species, habitat models derived from one region are often extrapolated to others. However, extrapolation can be inappropriate due to regional variation of habitat selection. Accounting for the ecological mechanisms causing such variation is necessary to resolve this problem. We focused on grey-faced buzzards in agricultural landscapes of Japan, which show geographically different habitat selection. To determine whether this variation is caused by the difference in climatic conditions at geographical scales or the difference in agricultural practices at smaller regional scales, we surveyed distributions of buzzards and their major prey (frogs/orthopterans) in regions differing in rice-transplanting schedules within the same climatic zone. We found that buzzards preferred paddy-forest landscapes in the early transplanting regions, but grassland-forest landscapes in the late transplanting regions. Frogs were more abundant in the early transplanting regions due to flooded paddies, while the abundance of orthopterans did not differ. The regional variation in habitat selection of buzzards may be due to different prey availabilities caused by different agricultural schedules. We propose that habitat suitability assessments of organisms inhabiting agricultural landscapes should consider differences in production systems at regional scales and such regional partitioning is effective for accurate assessments.

Autumn Migration of Diurnal Raptors across Kenting National Park, Taiwan, along the East-Asian Oceanic Flyway

ABSTRACT Diurnal raptors were counted during their southward migration in autumn of 2019 at Kenting National Park, southern Taiwan, an important hawkwatch site along the East-Asian Oceanic Flyway. Observations were conducted from 1 September to 31 October 2019 in the morning hours, but the observation period was extended to 1400 H whenever large numbers of raptors passed the site before noon. A total of 329,559 individuals of 14 migratory raptor species was recorded. The Chinese Sparrowhawk (Accipiter soloensis) and Gray-faced Buzzard (Butastur indicus) made up 78.3% (257,971 birds) and 21.6% (71,045 birds) of the total, respectively. The number of Chinese Sparrowhawks increased significantly when we extended the survey duration from 1200 H to 1400 H (paired t-test, t = 2.44, P = 0.04), but the number of Gray-faced Buzzards did not (t = 1.94, P = 0.09). Thus, Chinese Sparrowhawks may continue passing the site en route to the Philippine Islands in the afternoon hours, whereas Gray-faced Buzzards usually stop migrating in early afternoon, at least under certain conditions. How prevailing wind conditions along the East-Asian Oceanic Flyway in autumn shape the different migratory strategies of these two hawk species requires further study.

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.

Measurement of Grey-faced Buzzard <i>Butastur indicus </i>wingspan during flight, using a laser rangefinder

猛禽類の飛行高度と位置を地図上に図示することは，地形と関連した渡りルート選択の理解や風力発電所計画地点における影響評価などにおいて有益である．これまで，サシバButastur indicusを対象に翼開長の画像寸法から飛行高度位置の図化を試みているが，この手法では翼開長105 cmとしてサシバまでの距離を求めている．しかしながら，翼開長105 cmは飛翔時の計測値ではないため，測定結果に曖昧さがあった．そこで，レーザー距離計を組み合わせた被写体と距離の同時撮影装置を用いて，サシバの飛翔時翼開長の実寸を測定した．その結果，飛翔時翼開長は平均98.9±3.6 cm（標準偏差）であった．今後，本測定結果を用いて，サシバの飛行高度位置測定法の精度向上を図りたい．

Use of Tail Feather Traits to Determine Sex of Adult Grey-faced Buzzards (Butastur indicus)

ABSTRACT Sex identification is an important research topic in avian ecology because easy and accurate sex identification is useful for studies of evolution, behavior, and population dynamics. We used field photographs to measure the markings on the tail feathers of adult Grey-faced Buzzards (Butastur indicus) breeding in Japan to elucidate the attributes that allow individual sex determination. We labeled the dark, horizontal bands B1, B2, and B3, starting from the tip of the tail feathers and proceeding toward the base; we designated the light, horizontal band between B1 and B2 as W1, and the light, horizontal band between B2 and B3 as W2. To clarify the difference between the tail feathers of the sexes, we measured the ratio of W2 to W1 (W2/W1) of the right tail feather 3, right tail feather 4, left tail feather 3, and left tail feather 4, and calculated the average of these four values (average W2/W1). We tested these ratios using the Brunner-Munzel test to determine whether they discriminated the sexes. We found that the four individual feather ratios differed significantly between males and females. In addition, males and females could be reliably distinguished using the average W2/W1. This method can be widely used for fast, non-invasive sexing of Grey-faced Buzzards because it does not require sophisticated techniques.

GIS-Modeling of Island Hopping Through the Philippines Demonstrates Trade-Offs Migrant Grey-Faced Buzzards During Oceanic Crossings

Migration can be costly with consequences that can influence population trajectories. These costs and consequences are especially heightened during over-water travels, which can be high-risk events for birds. We created spatial models to evaluate potential migratory responses of “oceanic”, island-hopping grey-faced buzzards that encounter variation in landscape parameters and weather as they move through and out of the Philippine archipelago. We constrained the modeled routes to enter the island chain at Basco and to use one of four potential exit points in the south of the country, either Balabac, Bongao, Balut Island, or Cape San Agustin. We used all possible combinations of our three external parameters (stopover sites, water crossings and wind direction) to model alternative migratory routes for each of the four exit points (n = 20 migratory routes). Modeled grey-faced buzzard routes were between 1,582 and 2,970 km. Routes overlapped over eastern and central Luzon, along a leading line created by the Sierra Madre Mountains. Routes also overlapped and suggested unavoidable over-water crossings between Mindoro and Palawan, Negros and Zamboanga del Norte, and Leyte and Surigao. Our models suggest that the optimal migratory strategy for these birds is to find the shortest route to an exit point with the greatest possible access to stopover habitats and fewest open-water crossings under wind resistance. Understanding how each of these external factors affected the geography and characteristics of the migratory routes helps us to understand the context for different migratory strategies of birds that face dangerous open-water crossings on migration.

Analysis of the Genetic Diversity and Structure of the Grey-Faced Buzzard (Butastur indicus) in Japan, Based on mtDNA.

The grey-faced buzzard (Butastur indicus) is a raptor that inhabits East Asia, including Japan. Because the number of individuals has decreased by 75% over the last 40 years, this species is classified as vulnerable (VU) in Japan. In the present study, wesought to reveal the genetic structure of the Japanese grey-faced buzzard population at several breeding sites, and to assess the levels of genetic diversity within the Japanese population. We sequenced 555 bp of the mitochondrial DNA of 96 individuals sampled during the breeding season at 18 sites, and 11 individuals sampled during the winter season at one site. In total, 21 variable sites were found in the control region, and we detected 26 haplotypes among the 107 individuals. Fukuoka represented the core breeding area for grey-faced buzzards, as half of all haplotypes were detected there. Four unique haplotypes were detected in the overwintering area. The results of the network and mismatch distribution analyses indicated that the grey-faced buzzard has not experienced a genetic bottleneck in the past, but did experience recent population expansion. In addition, comparisons with other raptors revealed rich genetic diversity in the grey-faced buzzard population. Our results indicate that conservation of both breeding and wintering areas is important for the protection of the grey-faced buzzard.

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.

Identification of Aves, Herpetofauna and Arthropods in Miangas Island (Indonesia), the borderline of Wallacea ecoregion

Suryawan A, Yuliantoro I, Mayasari A, Christita M. 2016. Identification of Aves, Herpetofauna and Arthropods in Miangas Island (Indonesia), the borderline of Wallacea ecoregion. Biodiversitas 18: 1528-1537. Miangas Island is located on the northeast of Wallacea and bordered by the Philippines and it belongs to Talaud archipelago. This study aims to identify the species of terrestrial wildlife in Miangas Island. Observations used the direct encounter method starting at 7:00 to 17:00 pm and they were conducted through four times visits in October and December 2015, April and May 2016. Some species were found, such as 15 species of birds, 3 species of lizards, 1 snake and 1 species of Arthropods. Hirundapus caudacutus and Butastur indicus are migrant bird species. Lamprolepis smaragdina is green and classified as tree climber type. It is included to hybrid lizard type of the Pacific and the Philippines. Based on IUCN database, Eos histrio is classified as endangered group (E), Ducula pickeringii as vulnerable (V) Todirhamphus enigma enigma is classified as near threatened group (NT), Birgus latro is classified as Data deficient (DD), while Butastur indicus, Lanius Schach, Nectarinia jugular plateni, Todirhamphus chloris, Hirundo tahitica, Hirundapus caudacutus, Egretta sacra, Ardea alba, Anthus cervinus, Motacilla cinerea, Cuculus saturatus, Passer Montanus, Ducula pickeringii, Eutropis multicarinata multicarinata, Lamprolepis smaragdina, Emoia caeruleocauda and Laticauda laticauda are classified as low risk (LC).

福岡県におけるサシバ<i>Butastur indicus</i>の営巣環境─地域によって異なる特性─

福岡県におけるサシバ<i>Butastur indicus</i>の営巣環境─地域によって異なる特性─

Species Composition, Timing, and Weather Correlates of Autumn Open-Water Crossings By Raptors Migrating Along the East-Asian Oceanic Flyway

Abstract Raptor migration rarely involves long-distance movements across open oceans. One exception occurs along the East-Asian Oceanic Flyway. We collected migration data at two terrestrial hawkwatch sites along this flyway to better understand open-ocean movements along this largely overwater corridor. At the northern end of the Philippines, at Basco on the island of Batan, we recorded 7587 migratory raptors in autumn 2014. Near the southern end of the Philippines, at Cape San Agustin on the island of Mindanao, we recorded 27,399 raptors migrating in autumn 2012. Chinese Sparrowhawks (Accipiter soloensis) were the most common raptors observed, making up approximately 89% and 92% of total records for Basco and Cape San Agustin, respectively. The Grey-faced Buzzard (Butastur indicus) was the second most common raptor migrant, accounting for 8% of the total counts at both watch sites. The migration period was about 1–2 wk earlier at Basco, the more northerly site, than at Cape San Agustin. Overwater flight...

The Feather Structure of Oriental Honey Buzzards (Pernis ptilorhynchus) and Other Hawk Species in Relation to Their Foraging Behavior.

The basic structure of a bird feather may be adapted to suit a variety of functions on different parts of the body and in different species. In Oriental honey buzzards (Pernis ptilorhynchus), a species which often preys on the larvae of bees and wasps, it is thought that the bird's integument may provide protection against the stings of these insects. We investigated the structure of Oriental honey buzzard feathers from the face, head, and neck using light and scanning electron microscopy. The structure and appearance of the feathers were compared with those of two other hawk species which live in similar habitats but have different diets: the grey-faced buzzard (Butastur indicus) and the black kite (Milvus migrans). All feathers of Oriental honey buzzards that were examined were smaller than feathers from the same regions of the body of other species and had a reduced number of plumulaceous barbs; barbs were also closer together at the feather tip and had a high barbule density. The small 'scale feathers' on the face had deep barbules with a curved, armor-like appearance, which may help prevent stings from reaching the skin. A unique filamentous substance was observed on all the honey buzzard feathers, particularly those from around the eye of a male bird. It is possible that this may be related to a chemical defense mechanism to deter bees and wasps.

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.

Modernization of drainage systems decreases gray-faced buzzard occurrence by reducing frog densities in paddy-dominated landscapes

Modernization of drainage systems is suspected of causing a deterioration in the biodiversity of paddy-dominated landscapes that are substitutes for natural wetlands. Here, we focused on the gray-faced buzzard (Butastur indicus), a top predator that inhabits agricultural landscapes in East Asia. We evaluated the impacts of drainage system modernization on buzzards by measuring reductions in paddy-dwelling frogs, a major prey for buzzards that are common in rice fields. Field surveys were conducted in yatsu valleys (“yatsu” refers to small, narrow valleys in which rice cultivation often dominates the valley bottom) in Shimane prefecture, western Japan. We found that the distribution of buzzards was positively correlated with the densities of black-spotted pond frogs (Pelophylax nigromaculatus) and forest green tree frogs (Rhacophorus arboreus), although the relationship between buzzards and pond frogs was stronger. In addition, pond frog density was negatively correlated with modern drainage systems, whereas tree frog density did not show such a pattern. Therefore, modern drainage systems may reduce the buzzard population indirectly by reducing pond frog densities.

Grey-faced Buzzard <I>Butastur Indicus</I>: First Record from India

Grey-faced Buzzard <I>Butastur Indicus</I>: First Record from India