Animal mortality

About: Animal mortality is a research topic. Over the lifetime, 526 publications have been published within this topic receiving 14887 citations.

An Attack by a Polar Bear on a Juvenile Beluga

Abstract: Cunningham Inlet, Somerset Island, in the Canadian Arctic is frequented each summer by large numbers of beluga ( Delphinapterus leucas ). They migrate to the head of the inlet, and then invade the mouths of the two streams which drain into it. … On 26 July 1974, a sexually-immature female beluga was discovered stranded on a gravel bar at the head of the inlet. Because it could not be manhandled back to water, and would have died from suffocating and dehydration, the whale was shot. The brown colour, shape of head and length (271 cm) of the animal suggested that it was between three and four years old, while the five to six growth layers present in the teeth indicated an age of 2½-3 years. The stomach was found to contain a few amphipods and some seaweed. The carcass carried deep but well-healed scars on the left dorso-lateral aspect caudal to the dorsal ridge. Their depth, and the fact that they were parallel in three cases, strongly suggested that the animal had been attacked by a large-clawed animal, probably a polar bear (Ursus maritimus ). … To our knowledge this paper constitutes only the third documented account of an attack on a beluga by a polar bear in the Canadian Arctic …. [All previously reported attacks, including an attack of captive belugas near Churchill, are also discussed in this article.]

A study of the activity of 2-(alkylamino)-1-phenyl-1-ethanethiosulfuric acids against infection by Schistosoma mansoni in a murine model.

Abstract: The schistosomicidal activities of seven 2-(alkylamino)-1-phenyl-1-ethanethiosulfuric acids (1a-g) (R=propyl, isopropyl, butyl, isobutyl, t-butyl, sec-butyl, cyclohexyl, respectively) were determined in female Swiss mice infected with Schistosoma mansoni. The compounds were administered in a single oral dose of 800 mg/kg to groups of 15 mice infected with 50 cercariae each. All the compounds were found to be active, a high animal mortality being observed with 1e. These compounds have a high specificity against female worms (64-100% reduction vs. 33-61% reduction in male worms). The test was repeated, a 400-mg/kg sub-dose of 1f also being tested, and similar results were observed. A 94% reduction in the number of female worms was observed when compound 1c was administered in a single 800-mg/kg dose to animals infected with 80 cercariae. Finally, the test was repeated with single 800 mg/kg oral doses of compounds 1e (highly purified) and 1f and a 400-mg/kg sub-dose of 1c. The toxicity of 1e was confirmed, while the animals that received 1c and 1f presented reductions in the worm loads corresponding to 45.9% (male worms) and 84.8% (female worms) for 1c and 50.4% (male worms) and 94.2% (female worms) for 1f.

Predator-prey spatial game as a tool to understand the effects of protected areas on harvester-wildlife interactions.

Abstract: No-take reserves are sometimes implemented for sustainable population harvesting because they offer opportunities for animals to spatially avoid harvesters, whereas harvesters can benefit in return from the reserve spillover. Here, we used the framework of predator-prey spatial games to understand how protected areas shape spatial interactions between harvesters and target species and determine animal mortality. In these spatial games, the "predator" searches for "prey" and matches their habitat use, unless it meets spatial constraints offering the opportunity for prey to avoid the mortality source. However, such prey refuges could attract predators in the surroundings, which questions the potential benefits for prey. We located, in the Geneva Basin (France), hunting dogs and wild boar Sus scrofa L. during hunting seasons with global positioning systems and very-high-frequency collars. We quantified how the proximity of the reserve shaped the matching between both habitat uses using multivariate analyses and linked these patterns to animals' mortality with a Cox regression analysis. Results showed that habitat uses by both protagonists disassociated only when hunters were spatially constrained by the reserve. In response, hunters increased hunting efforts near the reserve boundary, which induced a higher risk exposure for animals settled over the reserve. The mortality of adult wild boar decreased near the reserve as the mismatch between both habitat uses increased. However the opposite pattern was determined for younger individuals that suffered from the high level of hunting close to the reserve. The predator-prey analogy was an accurate prediction of how the protected area modified spatial relationships between harvesters and target species. Prey-searching strategies adopted by hunters around reserves strongly impacted animal mortality and the efficiency of the protected area for this harvested species. Increasing reserve sizes and/or implementing buffer areas with harvesting limitations can dampen this edge effect and helps harvesters to benefit durably from source populations of reserves. Predator-prey spatial games therefore provide a powerful theoretical background for understanding wildlife-harvester spatial interactions and developing substantial application for sustainable harvesting.

Seasonal Variation in Wildlife Roadkills in Plantations and Tropical Rainforest in the Anamalai Hills, Western Ghats, India

Abstract: Wildlife–vehicle collisions on the roads lead to mortality of a range of animal taxa both within and around wildlife reserves. Quantifying and understanding impacts of roads on wildlife mortality are essential for identifying vulnerable taxa and suitable mitigation measures. We studied animal mortality on roads in relation to habitat and season in the Anamalai Tiger Reserve and adjoining Valparai plateau in the Western Ghats, India. Habitats were broadly classified as forest, monoculture plantations (tea, coffee, eucalyptus) and mixed. Eleven road transects of 3–12 km length were surveyed between 9 and 12 times each during monsoon (2011) and summer (2012). We recorded 2969 roadkills (mean = 2.01/km) during the 1473.4 km of road surveys carried out. The overall roadkill rate was 21.2 (± 3.87 SE) individual kills/10 km. Amphibians were most frequent in roadkills (overall roadkill rate of 9.3 ± 2.17 SE kills/10 km, n = 1307), followed by invertebrates and unidentified taxa (7.6 ± 1.81 SE kills/10 km, n = 1066). Roadkill rate was 2.4 times higher in monsoon than summer, with amphibians particularly averaging higher kill rate during monsoon. Frequency of roadkills of various animal groups differed between seasons in different habitats. In both the seasons, most roadkills were recorded mainly in tea, forest, and forest–tea habitats. Relative to length of roads through forest, a disproportionately large number of roadkills of herpetofauna and mammals were recorded in forest habitat. Higher vehicular movements, including tourist traffic, road widening, removal of native plants along roads and construction of sidewalls without breaks obstruct animal movements and may be responsible for roadkills. Designing roads to be more permeable for safe animal movement, particularly where roads pass through forest, and sensitizing highways authorities are essential to reduce animal mortality and make roads more wildlife-friendly in this region.

Enhancement of liver size by stimulation of intact rat liver with exogenous hepatotrophic factors

Abstract: In mammals, liver size is related to animal body weight at the 2.5 to 3% proportion, a ratio mediated by the afflux of hepatotrophic factors. Formulas capable of modifying this ratio have been developed in previous studies on the rat, with enhancement of liver size brought about by intraperitoneal (portal) infusion of exogenous factors such as glucose, amino acids, insulin, glucagon, vitamins, electrolytes, and triiodothyronine. However, the efficacy of these formulations was accompanied by increased animal mortality (PARRA et al.19,20 ). The present study, which was carried out with small methodological modifications on a larger number of rats using daily intraperitoneal injections of a solution of exogenous hepatotrophic factors (40 ml/kg) for seven days, confirms the previous findings, with a 114.16 ± 7.90% enhancement of liver size beyond the expected value for the body weight of the animal. However, the problem of animal mortality was not fully resolved.