Ecol Appl. 2015 Jun;25(4):968-90.
Abstract
Conserving
a declining species that is facing many threats, including overlap of
its habitats with energy extraction activities, depends upon identifying
and prioritizing the value of the habitats that remain. In addition,
habitat quality is often compromised when source habitats are lost or
fragmented due to anthropogenic development. Our objective was to build
an ecological model to classify and map habitat quality in terms of
source or sink dynamics for Greater Sage-Grouse
(Centrocercus urophasianus) in the Atlantic Rim Project Area (ARPA), a
developing coalbed natural gas field in south-central Wyoming, USA. We
used occurrence and survival modeling to evaluate relationships between
environmental and anthropogenic variables at multiple spatial scales and
for all female summer life stages, including nesting, brood-rearing,
and non-brooding females. For each life stage, we created resource
selection functions (RSFs). We weighted the RSFs and combined them to
form a female summer occurrence map. We modeled survival also as a
function of spatial variables for nest, brood, and adult female summer
survival. Our survival-models were mapped as survival probability
functions individually and then combined with fixed vital rates in a
fitness metric model that, when mapped, predicted habitat productivity
(productivity map). Our results demonstrate a suite of environmental and
anthropogenic variables at multiple scales that were predictive of
occurrence and survival. We created a source-sink map by overlaying our
female summer occurrence map and productivity map to predict habitats
contributing to population surpluses (source habitats) or deficits (sink
habitat) and low-occurrence habitats on the landscape. The source-sink
map predicted that of the Sage-Grouse
habitat within the ARPA, 30% was primary source, 29% was secondary
source, 4% was primary sink, 6% was secondary sink, and 31% was low
occurrence. Our results provide evidence that energy development and
avoidance of energy infrastructure were probably reducing the amount of
source habitat within the ARPA landscape. Our source-sink map provides
managers with a means of prioritizing habitats for conservation planning
based on source and sink dynamics. The spatial identification of high
value (i.e., primary source) as well as suboptimal (i.e., primary sink)
habitats allows for informed energy development to minimize effects on
local wildlife populations.
