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Quantifying temporal variation in dietary niche to reveal drivers of past population declines
Author(s) -
Cheeseman Amanda E.,
Tanis Brian P.,
Finck Elmer J.
Publication year - 2021
Publication title -
functional ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 154
eISSN - 1365-2435
pISSN - 0269-8463
DOI - 10.1111/1365-2435.13765
Subject(s) - niche , biology , ecology , population , generalist and specialist species , ecological niche , ecosystem , population decline , population growth , habitat , demography , sociology
Given the long and dynamic history of anthropogenic disturbances to ecosystems, it is difficult to determine the drivers of past population declines. These uncertainties dilute the efficacy of conservation efforts and might hinder species and ecosystem recovery. Niche quantification can be a useful tool for understanding drivers of past population declines. Niche parameters reflect key resources used, providing insight into the conditions needed to achieve population stability. By reconstructing a population's niche position and space over a period of decline and comparing to historic baselines, shifts in the realized niche of a species can be assessed. Comparing shifts to historic information on resource availability and timing of declines can allow practitioners to identify probable drivers of species decline. We demonstrated the utility of this technique by reconstructing parameters of isotopic dietary niche over a 130‐year period and comparing isotopic niche reconstructions to land use and crop harvests during this same period via regression and Bayesian standard ellipsoid (SIBER) analyses. We use a formerly widespread but now endangered species, the eastern spotted skunk Spilogale putorius , addressing the hypothesis that land use change and agricultural intensification led to a historical collapse of key dietary resources which correlates with population declines in this species. To help control for isotopic variability unrelated to population decline, we compare trends to those of a secure, but ecologically similar generalist mesocarnivore, the striped skunk Mephitis mephitis , across the same spatiotemporal scale. We present evidence that historic dietary changes occurred in spotted skunks in the early 1900s but not to the same degree in striped skunks. Changes in isotopic composition correspond with the temporal period of decline and are explained by concurrent changes in land use. These results support the hypothesis that loss of key dietary resources as a result of land use change and agricultural intensification played a significant role in population declines of spotted skunks in this region. A free Plain Language Summary can be found within the Supporting Information of this article.