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Viability and Conservation of an Exploited Sage Grouse Population
Author(s) -
Johnson Kris Harold,
Braun Clait E.
Publication year - 1999
Publication title -
conservation biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.2
H-Index - 222
eISSN - 1523-1739
pISSN - 0888-8892
DOI - 10.1046/j.1523-1739.1999.97284.x
Subject(s) - geography , population viability analysis , ecology , biology , habitat , endangered species
We analyzed the viability of the Sage Grouse ( Centrocercus urophasianus ) population of North Park, Colorado, to evaluate its supposed decline due to hunting pressure and habitat degradation. Demographic data from 23 years of surveys were used to parameterize a post‐breeding, female‐based projection matrix with three life stages: juveniles, yearlings, and adults. The population was found to be approximately stable or in decline only if immigration and apparent surveying errors were factored from the data set. Adult and juvenile survival and adult and juvenile reproduction, respectively, were identified as the most limiting demographic factors. Empirical evidence from designed experiments with Sage Grouse has shown that these demographic factors respond markedly to habitat manipulations, especially brush manipulation. Several plausible management scenarios were evaluated with 100‐year population projections generated through Monte Carlo simulation (1000 iterations), sampling from a normal probability distribution entraining the observed variability in each demographic parameter (95% confidence limits). Habitat manipulations to achieve moderate levels (~15% canopy cover) of sagebrush ( Artemisia tridentata ) are recommended. Regression analyses with power tests showed correspondence between hunting mortality and total mortality for juveniles and adults. Provided that habitat manipulations improve the survival of juveniles and adults, population viability may be conserved without reducing harvest by hunters.