Evolutionary effects of trophy hunting


The potential evolutionary consequences of selective harvest are now routinely considered in fisheries management, but are often met with hostility by wildlife managers.  I will discuss strong evidence of artificial evolution of smaller horns in bighorn sheep (Ovis canadensis) and review the conditions under which similar evolution can be expected for other trophy-hunted species.  Bighorn sheep in most of Canada are hunted based on a morphological criterion: only rams whose horns describe a minimum degree of curl can be shot.  There is no quota: an unlimited number of hunting permits are available to residents of each province.  This harvest regime has been in place for 7-8 sheep generations.  Rams with rapidly-growing horns are shot as young as age 4, but large horns do not lead to high mating success until about 6-7 years of age.  Negative artificial selective pressure on horn size through the hunt sets in 2-3 years before positive sexual selection.  At Ram Mountain, Alberta, this harvest regime led to a genetic decline in horn size, which stopped but was not reversed when the hunt was ended.  Where mountain sheep (O. canadensis and O. dalli) are under heavy hunting pressure, horn size declines.  Genetic rescue from protected areas is weak because the hunt continues until rams start exiting those areas.  Once wildlife managers accept that evolution happens, there are obvious ways to prevent undesirable evolutionary consequences of trophy hunting.


I am a Professor at the Université de Sherbrooke in Québec, Canada.  I am interested in how individual differences affect the evolutionary ecology and population dynamics of large herbivores, currently including research on bighorn sheep, caribou, and eastern grey kangaroos.  My research is based on long-term monitoring of marked individuals, ideally of known age and parentage.  With mixed success, I argue that evolution is important for wildlife management.  From 2002 to 2006 I chaired the Committee on the Status of Endangered Wildlife in Canada. 

Date & time

1–2pm 5 December 2017


Gould Seminar Room (Rm 235), Bldg 116, Gould Building, Daley Road, ANU


Marco Festa-Bianchet, Département de biologie, Université de Sherbrooke, Canada


 Loeske Kruuk
 6125 6931

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