Abstract: Poaching
is a prominent source of ‘hidden hurdles’, cryptic impacts of human
activities that may hinder the conservation of animal populations.
Estimating poaching mortality is challenging, as the evidence for
illegal killing is not outwardly obvious. Using resighting and recovery
data collected on 141 marked red deer Cervus elaphus
within the Stelvio National Park (central Italian Alps), we show how
multievent models allow to assess the direct impacts of illegal
harvesting on age- and sex-specific survival, accounting for uncertainty
over mortality causes.
Mortality
caused by poaching was consistently higher for males than for females
in all age classes. In males, the probability of dying from poaching was
higher for extreme age classes, while in females all age classes showed
fairly similar values of poaching mortality. The strong bias in
sex-specific poaching mortality was possibly due to trophy killing in
adult males and ‘bushmeat-like’ killing for private or commercial gain
in young males and in females.
A
robust assessment of age- and sex-specific prevalence of poaching in
wildlife populations is pivotal when illegal killing is of conservation
concern. This provides timely information on what segment of the
population is most likely to be affected. Besides obvious demographic
consequences on small populations, age- and sex-biased poaching
prevalence may contrast with the need to maintain ecosystem complexity
and may alter behavioral responses to human presence. The information
provided by multievent models, whose flexibility makes them adaptable to
many systems where individual-based data is part of population
monitoring, offers a support to design appropriate strategies for the
conservation of wildlife populations.
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