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Keywords:

  • Canis lupus;
  • survivorship;
  • road kills;
  • reproduction;
  • population structure

Abstract

Information on population parameters is rarely collected from carcasses. This method can be particularly useful – with limitations – when protected species are involved (e.g. the grey wolf Canis lupus in Italy). Local data on population structure, reproduction, survivorship and causes of mortality are necessary to build reliable conservation models to assess the state of a population and to predict its evolution. On the other hand, ‘best guesses’ or data from ecologically different areas have often been used to build population viability analysis and other conservation-oriented models. A sample of 154 wolf carcasses was found, collected and analysed from 1991 to 2001 in central-eastern Italy, the historic core of the wolf distribution range. Collision with a vehicle was the main cause of death in both sexes; however, road kills may be biased with a greater detectability, and we treated our data accordingly. Road kills were concentrated on the younger (≤4 years old) age classes, whereas fully adult wolves died mainly because of poaching, intraspecific strife and pathologies. Cubs and subadults (≤2 years old) showed a mortality peak in November/December, at the beginning of the dispersal period, whereas adults died mainly in January/February (mating season). The population structure of our sample of wolf carcasses appeared to be well balanced, although perinatal and cub mortality was underestimated. The sex ratio was 1:1 in the younger age classes and 1:0.7 in the older age classes. Only 20.7% of females, 2–6 years old, showed signs of reproduction; placental scar and embryo number varied from one to seven (mean, 4.4) per individual. Survivorship theoretical curves indicated a fair survival of cubs and subadults, but a steep decline as wolves approached maximum life span (9 years old). Our data and other published data on food habits and genetic features of the wolf in central-eastern Italy suggest that, despite ongoing heavy human-induced losses, this predator has fully recovered in the last 30 years from the brink of extinction.