Removing the threat of diclofenac to critically endangered Asian vultures.
(9/97)
Veterinary use of the nonsteroidal anti-inflammatory (NSAID) drug diclofenac in South Asia has resulted in the collapse of populations of three vulture species of the genus Gyps to the most severe category of global extinction risk. Vultures are exposed to diclofenac when scavenging on livestock treated with the drug shortly before death. Diclofenac causes kidney damage, increased serum uric acid concentrations, visceral gout, and death. Concern about this issue led the Indian Government to announce its intention to ban the veterinary use of diclofenac by September 2005. Implementation of a ban is still in progress late in 2005, and to facilitate this we sought potential alternative NSAIDs by obtaining information from captive bird collections worldwide. We found that the NSAID meloxicam had been administered to 35 captive Gyps vultures with no apparent ill effects. We then undertook a phased programme of safety testing of meloxicam on the African white-backed vulture Gyps africanus, which we had previously established to be as susceptible to diclofenac poisoning as the endangered Asian Gyps vultures. We estimated the likely maximum level of exposure (MLE) of wild vultures and dosed birds by gavage (oral administration) with increasing quantities of the drug until the likely MLE was exceeded in a sample of 40 G. africanus. Subsequently, six G. africanus were fed tissues from cattle which had been treated with a higher than standard veterinary course of meloxicam prior to death. In the final phase, ten Asian vultures of two of the endangered species (Gyps bengalensis, Gyps indicus) were dosed with meloxicam by gavage; five of them at more than the likely MLE dosage. All meloxicam-treated birds survived all treatments, and none suffered any obvious clinical effects. Serum uric acid concentrations remained within the normal limits throughout, and were significantly lower than those from birds treated with diclofenac in other studies. We conclude that meloxicam is of low toxicity to Gyps vultures and that its use in place of diclofenac would reduce vulture mortality substantially in the Indian subcontinent. Meloxicam is already available for veterinary use in India. (+info)
Falcon adenovirus infection in breeding Taita falcons (Falco fasciinucha).
(10/97)
Four female and 3 male Taita falcons (Falco fasciinucha) out of a breeding colony of 14 Taita falcons (7 pairs) died during the breeding season after showing lethargy and anorexia for 1 to 2 days. All animals were submitted for necropsy. Gross lesions in the female falcons were characterized by anemia secondary to marked hemorrhage into the ovary and oviduct, serofibrinous effusion into the cardioabdominal cavity and serosal petechiae. In addition, marked necrotizing splenitis and pulmonary hemorrhage were present. Histologically, the female falcons had mild necrotizing hepatitis with numerous intranuclear inclusion bodies and necrotizing splenitis with rare inclusion bodies. There were no gross lesions in the male falcons, and the histological lesions were characterized by urate deposition and rare intranuclear inclusion bodies in the renal tubular epithelial cells. Adenoviral particles were found by electron microscopy in the cloacal contents of the female Taita falcons but not in the male falcons. DNA in situ hybridization revealed widespread aviadenoviral nucleic acid within the nuclei of hepatocytes, renal tubular epithelial cells, and adrenal cells in the female falcons but no aviadenoviral nucleic acid in 1 male falcon and only a low quantity of adenoviral nucleic acid in the liver and kidney of another male Taita falcon. PCR amplified aviadenoviral DNA in the liver and intestine of all Taita falcons. The amplicons were sequenced, and the virus was identified as falcon adenovirus. The deaths of the female and male birds were attributed to the aviadenovirus infection. (+info)
Food-limitation in a generalist predator.
(11/97)
Investigating food-limitation in generalist predators is difficult, because they can switch to alternative prey, when one of their staple prey becomes scarce. Apart from data on the dynamics of the predator population, a robust study requires: (i) a documentation of the predator's entire prey base; and (ii) an experimental or natural situation, where profitable dietary shifts are impossible, because several preferred prey species decline simultaneously. Here, we provide a detailed description of how food-supply has limited a generalist avian top predator, the northern goshawk Accipiter gentilis. In our study area, populations of several principal goshawk prey species crashed simultaneously during 1975-2000, whereas other extrinsic factors remained essentially unchanged. The breeding and non-breeding segments of the local goshawk population declined markedly, associated with a significant increase in nest failures. Brood size of successful pairs remained unaffected by changes in prey availability. Breeding recruitment ceased at a time when potential replacement birds ('floaters') were still present, providing a rare empirical demonstration of an 'acceptance threshold' in raptor territory choice. To investigate how goshawk diet changed in response to varying food-supplies, we make novel use of an analytical tool from biodiversity research-'abundance-biomass-comparison curves' (ABC curves). With increasing levels of food-stress, the dominance of principal prey species in the diet decreased, and the number of small-bodied prey species increased, as did intra-guild predation. Our finding that breeder and non-breeder segments declined in concert is unexpected. Our results carry the management implication that, in food-limited raptor populations, externally induced breeder mortality can rapidly depress population size, as losses are no longer buffered when floaters reject breeding opportunities. (+info)
Linking ecology, behaviour and conservation: does habitat saturation change the mating system of bearded vultures?
(12/97)
The social organization of a population is the consequence of the decisions made by individuals to maximize their fitness, so differences in social systems may arise from differences in ecological conditions. Here, we show how a long-lived species that used to breed monogamously, and at low densities, can change its mating system in response to habitat saturation. We found that a significant proportion of unpaired birds become potential breeders by entering high-quality territories, or by forming polyandrous trios as a strategy to increase their individual performance. However, productivity of territories was reduced when those occupied by breeding pairs changed to trios, suggesting that the third individual was costly. The decision of some individuals to enter into breeding trios as subordinates also had clear negative consequences to population demography. This unusual mating behaviour is thus compromising the conservation effort directed to this endangered species; management to encourage floaters to settle in other suitable but unoccupied areas may be beneficial. (+info)
Ultraviolet reflectance by the cere of raptors.
(13/97)
Ultraviolet (UV) signals have been shown to play key roles in social and sexual signalling in birds. Using a spectrophotometer, we analysed the colour of the cere (skin above the beak) of a diurnal raptor, the Montagu's harrier (Circus pygargus), and show that it reflects in the UV part of the spectrum. The cere is a well-known sexual signal in raptors, with carotenoid based pigmentation being indicative of quality. We thus hypothesized that UV reflectance also signals quality. Accordingly, we found that in our sample of wild males, the location of the UV peak was related to the orangeness of cere and correlated with male body mass and condition (mass corrected for size). Also, males with brighter UV were mated to females that laid earlier, as expected if UV reflectance relates to a male's quality and attractiveness. Future studies should investigate the relationships between UV reflectance and carotenoid pigmentation of cere, and test how UV reflectance influences mate choice. (+info)
Toxicity of diclofenac to Gyps vultures.
(14/97)
Three endemic vulture species Gyps bengalensis, Gyps indicus and Gyps tenuirostris are critically endangered following dramatic declines in South Asia resulting from exposure to diclofenac, a veterinary drug present in the livestock carcasses that they scavenge. Diclofenac is widely used globally and could present a risk to Gyps species from other regions. In this study, we test the toxicity of diclofenac to a Eurasian (Gyps fulvus) and an African (Gyps africanus) species, neither of which is threatened. A dose of 0.8 mg kg(-1) of diclofenac was highly toxic to both species, indicating that they are at least as sensitive to diclofenac as G. bengalensis, for which we estimate an LD50 of 0.1-0.2 mg kg(-1). We suggest that diclofenac is likely to be toxic to all eight Gyps species, and that G. africanus, which is phylogenetically close to G. bengalensis, would be a suitable surrogate for the safety testing of alternative drugs to diclofenac. (+info)
Can predatory bird feathers be used as a non-destructive biomonitoring tool of organic pollutants?
(15/97)
The monitoring of different types of pollutants that are released into the environment and that present risks for both humans and wildlife has become increasingly important. In this study, we examined whether feathers of predatory birds can be used as a non-destructive biomonitor of organic pollutants. We demonstrate that polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and polybrominated diphenyl ethers (PBDEs) are measurable in one single tail feather of common buzzards (Buteo buteo) and that levels in this feather and internal tissues are significantly related to each other (0.35 < r < 0.76 for all 43 buzzards; 0.46 < r < 0.84 when excluding 17 starved birds). Our findings provide the first indication that feathers of predatory birds could be useful in non-destructive biomonitoring of organic pollutants, although further validation may be necessary. (+info)
Mallophaga species on long-legged buzzards (Buteo rufinus): new records from Turkey.
(16/97)
This study was carried out on two long-legged buzzards that were brought for treatment to the surgery clinic of the Veterinary Faculty, University of Selcuk. A few lice were observed on the body surfaces of the birds. Forty-seven lice were collected from the buzzards. The lice were preserved in a tube containing 70% ethanol. They were mounted on slides separately after being cleared in lactophenol. Four species of lice (Laemobothrion maximum, Degeeriella fulva, Craspedorrynchus platystomus, and Colpocephalum sp.) were identified by microscopical examination. The specimens of Colpocephalum could not be identified at the species level because of poor conditions of some morphological characteristics such as chaetotaxy of the body or male genitalia. (+info)