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Divergence in sink contributions to population persistence
Citation:
Heinrichs, J., J. Lawler, N. Schumaker, AND C. Wilsey. Divergence in sink contributions to population persistence. Presented at Society for Conservation Biology, North America Congress for Conservation Biology, Missoula, MT, July 13 - 16, 2014.
Impact/Purpose:
Wildlife are a concern to The Environmental Protection Agency for many reasons. Wildlife are indicators of ecosystem health, they respond to compounds and activities that are regulated by the Agency, they represent ecosystem services, and more. Population viability analysis (PVA) models are widely used to forecast trends in wildlife population size and distributions through time. This short presentation will discuss efforts being made to improve PVA models through the addition of additional biological realism, and through enhancements that add relevance to managers and regulators. This spoken presentation will use the northern spotted owl, the Ord’s kangaroo rat, and the black-capped vireo as a case studies to illustrate the new research advancements. These are all species of conservation concern that are heavily impacted by human activities.
Description:
Population sinks present unique conservation challenges. The loss of animals in sinks can compromise persistence. Conversely, sinks can bolster population sizes, improving viability. To assess the contribution of sinks to regional persistence, we simulated the removal of sink habitats of three endangered species and measured changes in populations. Results suggest that sink contributions vary widely. Sinks can be detrimental, particularly in populations with traps or low inter-annual growth rates (e.g., Alberta’s Ord’s kangaroo rat), or benign in robust populations (e.g., black-capped vireos with low parasitism). Sinks, including traps, can be crucial in delaying declines when there are few sources (e.g., vireos with high parasitism). The roles of sinks can also be nuanced, with sinks supporting larger, more variable populations that are subject to greater extinction risk (e.g., northern spotted owls). Actions based on assumptions that sinks are generally harmful, or generally helpful, may risk undermining conservation efforts for declining populations.