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Variation in demography, condition and dietary quality of hares Lepus europaeus from high-density and low-density populations

Jennings, Nancy, Smith, Rebecca K., Hackläänder, Klaus, Harris, Stephen, White, Piran C. L.
Wildlife biology 2006 v.12 no.2 pp. 179-189
Lepus, adults, blood serum, body condition, body size, body weight, bone marrow, breeding, demography, diet, energy, fallow, fields, grasslands, habitats, hares, kidneys, lactating females, lactation, litter size, mortality, nitrogen, nutritional adequacy, pastures, population density, predation, shelterbelts, urine, weather, winter, young animals, England, Wales
Numbers of European hares Lepus europaeus have declined throughout Europe due to agricultural intensification. However, hares are more common in intensive arable areas than in pastural areas. To identify factors limiting populations, functional explanations for differences in density of hares were sought. We compared demography (litter size, prenatal mortality and participation in breeding by females), body condition (urinary and serum nitrogen, kidney fat, bone marrow fat, skeletal size and body weight), and dietary quality of hares from parts of England and Wales where they are present at relatively high densities (arable habitats) and at relatively low densities (pastural habitats). In pastural areas a lower proportion of adult females were lactating in late winter than in arable areas. Recruitment was therefore lower in pastural than in arable habitats. Hares from pastural areas were smaller, lighter and had less fat than those from arable areas, but dietary quality was similar. Thus hares in low-density populations from pastural areas were able to obtain a good-quality diet, but expended more energy and were unable to maintain body condition as well as those from arable areas. Pastural habitat, which in England and Wales is relatively warm and wet, is suboptimal for hares. The reduced recruitment and chance of survival of hares in the pastural habitats we describe may explain the differences in density of hares in arable and pastural habitats. Efforts to conserve the hare should focus on the reduction of predation and exposure to unfavourable weather by the provision of year-round vegetative cover (such as fallow land, rough grassland and shelterbelts), to increase the chances of survival of leverets and adult hares.