Oriental White-backed Vulture Gyps Bengalensis Research Articles

Population and spatial breeding dynamics of a Critically Endangered Oriental White-backed Vulture Gyps bengalensis colony in Sindh Province, Pakistan

SummaryThe Critically Endangered Oriental White-backed Vulture Gyps bengalensis has declined across most of its range by over 95% since the mid-1990s. The primary cause of the decline and an ongoing threat is the ingestion by vultures of livestock carcasses containing residues of non-steroidal anti-inflammatory drugs, principally diclofenac. Recent surveys in Pakistan during 2010 and 2011 revealed very few vultures or nests, particularly of White-backed Vultures. From 2011 in the Tharparkar District of Sindh Province we monitored a colony of Oriental White-backed Vultures. Between 2011 and 2014 the number of active nests in this colony increased from 11 to 34 while nest density decreased from 13.7 to 9.2 nests km-2, suggesting that the colony is expanding. We conclude that the rate of increase is being subsidised by immigration, as the population demographics do not support the observed rate of increase in nests. We present the first analysis of spatial breeding dynamics for the Oriental White-backed Vulture and describe how a clustered pattern of nest trees in colonies supports a highly clustered pattern of nests. The spatial pattern of nests relies on both the distribution of trees and the ability of trees to support more than one nest. These results highlight that the preservation of larger nest trees and the sustainable management of timber resources are essential components for the conservation management of this species. We emphasise the high importance of this colony and a nearby Long-billed Vulture Gyps indicus colony in this area of Pakistan. Recommended conservation management actions include the continuation of a Vulture Safe Zone established in 2012, measuring breeding success, assessing dispersal and determining the impact of mortality on these populations.

Population trends of Critically Endangered Gyps vultures in the lowlands of Nepal

SummaryThree species of resident Gyps vulture are threatened with extinction in South Asia due to the contamination of domestic ungulate carcasses with the drug diclofenac. Observed rates of population decrease are among the highest recorded for any bird species, leading to total declines in excess of 99.9% for the Oriental White-backed Vulture Gyps bengalensis in India between 1992 and 2007. Vultures have declined in Nepal, but quantitative information on the rate and scale of decreases is unavailable. Road transect surveys for vultures, following the same route, methodology and timing, were undertaken in lowland areas of Nepal for seven years from 2002 to 2011. The seven survey transects followed Nepal’s East-West highway and covered 1,010 km in three years of the survey, and 638 km in the remaining four years. Slender-billed Vultures G. tenuirostris were very scarce, with a maximum of five individuals in 2002 and none recorded in 2010 and 2011. Oriental White-backed Vultures were most commonly recorded, but decreased from 205 to 68 birds over the survey period, with an estimated annual rate of decline of 14% a year. If population decreases commenced in Nepal in the same year as in India, then White-backed Vultures in Nepal have declined by 91% since the mid-1990s. Few resident Gyps vultures remained in Eastern and Central regions of Nepal, with just one, nine and six birds recorded in the three surveys that covered these regions. The majority of threatened Gyps vultures in lowland Nepal are now found in Western and Mid Western regions, where conservation efforts have been focused in the last six years. Removing veterinary diclofenac from across the country and continuing to manage effective “vulture safe zones” are essential to conserve Nepal’s remaining vulture populations.

Behavioural and virological studies on a rescued Oriental White-backed Vulture Gyps bengalensis from western Maharashtra, India

An exhausted Indian White-backed Vulture Gyps bengalensis was rescued in Maharashtra State, India. Examination revealed that it was not injured but was emaciated due to starvation. The vulture was fed in captivity by the Forest Department. To rule out the possibility of viral infections, cloacal, tracheal and serum samples were collected from the vulture. They were negative for Avian Influenza (AI) viruses, Newcastle Disease Virus (NDV), Infectious Bursal Disease Virus by virus isolation. We observed neck drooping behavior by vulture when approached by humans. The vulture flew away but after two days, was found dead 60km away, due to electrocution. Our report suggests that electrocution may also be an explanation for the decreasing numbers of vultures in India.

Vulture restaurants and their role in reducing diclofenac exposure in Asian vultures

The provision of supplementary food at vulture restaurants is a well-established tool in the conservation of vulture species. Among their many applications, vulture restaurants are used to provide a safe food source in areas where carcasses are commonly baited with poisons. Rapid and extensive declines of vultures in the Indian subcontinent have been attributed to the toxic effects of diclofenac, a pharmaceutical used in the treatment of livestock, to which vultures are exposed while feeding on the carcasses of treated animals. A vulture restaurant was established at the Oriental White-backed Vulture Gyps bengalensis colony at Toawala, in Punjab province Pakistan, to test the effectiveness of the technique in modifying ranging behaviour and mortality at the colony. Six male vultures were fitted with satellite transmitters to describe variation in movement and home-range during periods when safe food was alternately available and withheld at the vulture restaurant. There was considerable variation in individual home-range size (minimum convex polygons, MCP, of 1,824 km2 to 68,930 km2), with birds occupying smaller home-ranges centred closer to the restaurant being more successful in locating the reliable source of food. Fixes showed that 3 of the tagged vultures fed at the vulture restaurant and the home-range of each bird declined following their initial visit, with a 23–59% reduction in MCP. Mean daily mortality during provisioning was 0.072 birds per day (8 birds in 111 days), compared with 0.387 birds per day (41 birds in 106 days) during non-provisioning control periods. Vultures tended to occupy greater home-ranges, cover greater distances each day and spend proportionately more time in the air during the late brooding and post-breeding seasons. Attendance at the vulture restaurant also declined during this period with fewer birds visiting less often and no tagged vultures visiting the vulture restaurant at all. These findings indicate that vulture restaurants can reduce, but not eliminate, vulture mortality through diclofenac exposure and represent a valuable interim measure in slowing vulture population decline locally until diclofenac can be withdrawn from veterinary use.

Rapid population declines and mortality clusters in three Oriental white-backed vulture Gyps bengalensis colonies in Pakistan due to diclofenac poisoning

The population declines affecting Asian Gyps vultures are among the most rapid and geographically widespread recorded for any species. This paper describes the rates and patterns of mortality and population change over 4 years at three Oriental white-backed vulture Gyps bengalensis colonies in Pakistan: Dholewala (initially 421 pairs), Toawala (initially 445 pairs) and Changa Manga (initially 758 pairs). Vulture mortality led to the extirpation of two of these colonies (Changa Manga and Dholewala) in 3 years, and a decline of 54.3% in the third. Visceral gout, indicative of diclofenac poisoning, was the largest single cause of death in vultures examined. Annual adult mortality from diclofenac poisoning was significantly positively correlated with annual population declines at each colony indicating a direct causal relationship. Visceral gout occurred in temporal and spatial clusters suggesting multiple point sources of diclofenac exposure. The spatial and temporal distribution of dead vultures and approximate time since death were used to estimate minimum rates at which colonies encountered carcasses with sufficient diclofenac to cause mortality of 1.26–1.88 carcasses per colony per month. By estimating total carcass consumption at each colony, the percentage of carcasses contaminated with diclofenac was calculated as 1.41–3.02%, exceeding the minimum required to have caused the observed population decline. With populations declining by approximately 50% annually, the long term survival of Gyps vultures in South Asia will require the removal of diclofenac from vulture food and establishment of captive populations for future restoration once the environment is free from contamination.

Raillietiella trachea n. sp., a pentastomid from the trachea of an oriental white-backed vulture Gyps bengalensis taken in Pakistan, with speculation about its life-cycle

A cephalobaenid pentastomid, Raillietiella trachea n. sp., from the trachea of a fledgling oriental white-backed vulture Gyps bengalensis taken in Punjab Province, Pakistan, is described. This is the first record of a pentastomid from a fully terrestrial bird. Overall, gross morphology was typical of Raillietiella Sambon, 1910 in most respects. However, the hooks of R. trachea were of equal size, whereas in other members of the genus anterior hooks are smaller than the posterior hooks. The diagnosis of R. trachea was made on the basis of four near-patent females, all of which contained relatively few eggs (c.570), all at the same stage of maturity. Comparison with the only other genus known to infect birds (two species of Reighardia Ward, 1899 from the air-sacs of marine birds) revealed striking parallels in this aspect of the functional anatomy of the female reproductive tract. As far as we know, this mode of egg-production is not found in other raillietiellids. Extrapolating primarily from the experimental life-cycle studies of Reighardia sternae (Diesing, 1864) Ward, 1899, we surmise that the life-cycle of R. trachea has to be direct and that parasite behaviour is an integral part of parasite transmission. The evidence suggests that transmission is from vulture-to-vulture, per os.

Breeding and mortality of Oriental White-backed Vulture Gyps bengalensis in Punjab Province, Pakistan

Populations of Oriental White-backed Vulture Gyps bengalensis and Long-billed Vulture G. indicus declined in India between the mid 1980s and late 1990s. Regional reports from India described declines of 95–100% across a wide area. This study was conducted to investigate the breeding success and pattern of mortality in two vulture colonies (Dholewala and Changa Manga) within Punjab Province, Pakistan between December 2000 and June 2001. Breeding success was found to be 62% in Dholewala and 59% in Changa Manga. A total of 668 sick and dead vultures were collected of which 591 were less than one month post mortem. No significant variation was found in the weekly mortality rate of adult and subadult vultures during the study period spanning winter through summer. A peak in mortality rate was observed during late April and early May that corresponded to mortality of newly fledged juveniles. Minimum annual mortality rate in the adult breeding population was calculated to be 11.4% and 18.6% in Dholewala and Changa Manga respectively. In a subsample of dead vultures (n = 185) visceral gout was found in 80% of adults, 63% of subadults, 19% of juveniles and 13% of nestlings. These mortality rates were consistent with a rapid population decline. Results imply that the mortality factor responsible for the decline in Gyps vultures described in India is also present in Pakistan and will potentially lead to a population decline of a comparable magnitude.