New publication: Horn growth variation and hunting selection of the Alpine ibex

By Ulf Büntgen, Juan D. Galván, Atle Mysterud*, Paul J. Krusic, Lisa Hülsmann, Hannes Jenny, Josef Senn, and Kurt Bollmann in Journal of Animal Ecology

Abstract

  1. Selective hunting can affect demographic characteristics and phenotypic traits of the targeted species. Hunting systems often involve harvesting quotas based on sex, age and/or size categories to avoid selective pressure. However, it is difficult to assess whether such regulations deter hunters from targeting larger “trophy” animals with longer horns that may have evolutionary consequences.
  2. Here, we compile 44,088 annually resolved and absolutely dated measurements of Alpine ibex (Capra ibex) horn growth increments from 8,355 males, harvested between 1978 and 2013, in the eastern Swiss Canton of Grisons. We aim to determine whether male ibex with longer horns were preferentially targeted, causing animals with early rapid horn growth to have shorter lives, and whether such hunting selection translated into long‐term trends in horn size over the past four decades.
  3. Results show that medium‐ to longer‐horned adult males had a higher probability of being harvested than shorter‐horned individuals of the same age and that regulations do affect the hunters' behaviour. Nevertheless, phenotypic traits such as horn length, as well as body size and weight, remained stable over the study period.
  4. Although selective trophy hunting still occurs, it did not cause a measurable evolutionary response in Grisons' Alpine ibex populations; managed and surveyed since 1978. Nevertheless, further research is needed to understand whether phenotypic trait development is coinfluenced by other, potentially compensatory factors that may possibly mask the effects of selective, long‐term hunting pressure.

First published: 20 April 2018
DOI: 10.1111/1365-2656.12839
Publication webpage.

* Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway.
See the publication webpage for full author information


Press release from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL).

Tags: Journal of Animal Ecology;
Published May 23, 2018 11:16 AM - Last modified May 23, 2018 12:17 PM