Identifying and Controlling for Variation in Canid Harvest Data. Issue 7 (2nd July 2020)

• Record Type: Journal Article
• Authors: Bauder, Javan M.; Allen, Maximilian L.; Ahlers, Adam A.; Benson, Thomas J.; Miller, Craig A.; Stodola, Kirk W.
• Is Part Of: Journal of wildlife management. Volume 84:Issue 7(2020)
• Page Start: 1234
• Page End: 1245
• Publication Date: 2020-07-02
• Subjects: Canis latrans -- coyote -- gray fox -- Illinois -- pelt price -- red fox -- trapper effort -- trapper harvest -- Urocyon cinereoargenteus -- Vulpes vulpes; Wildlife management -- Periodicals; Zoology -- Periodicals; 333.954
• DOI: 10.1002/jwmg.21919
• Languages: English
• ISSNs: 0022-541X

Abstract

ABSTRACT: An accurate understanding of harvest trends is required for effective wildlife management. Trapper harvest data represent valuable long‐term data for evaluating patterns and trends for wildlife species at broad spatiotemporal scales. Inferring accurate trends from harvest data, however, first requires identifying and controlling for confounding factors that vary independent of abundance. We investigated trends in 43 years of trapper harvest data (1976–2018) from Illinois, USA, for red fox ( Vulpes vulpes ), gray fox ( Urocyon cinereoargenteus ), and coyote ( Canis latrans ) while controlling for factors that may affect trapper effort, including number of effective (i.e., successful) trappers, pelt price, gasoline price, winter unemployment, and winter weather conditions. Annual trapper harvest for red and gray foxes declined and was affected by gasoline price and winter unemployment, whereas annual trapper harvest for coyotes increased and was not strongly affected by other covariates. After adjusting for pelt price, harvest of red foxes was relatively stable, but harvest of gray foxes declined and harvest of coyotes increased. Effects of covariates on harvest per successful trapper varied by species; nevertheless, we detected an increasing trend for coyotes and decreasing trends for gray foxes and red foxes. Concordance across indices for gray foxes and coyotes was consistent with hypothesized declines for gray foxes and increases for coyotes in the midwestern United States. Trends for red foxes varied depending on how we accounted for potential confounding factors and it is unclear if these trends suggest population declines or distribution shifts to urban areas with reduced trapping susceptibility. Our results highlight the importance of understanding sources of variation in harvest data and that their effects can vary across species. © 2020 The Wildlife Society. Abstract : We used 42 years of data to evaluate the effects of trapper numbers, pelt price, socio‐economic factors, and weather conditions on variation in trapper harvest of red fox, gray fox, and coyote across Illinois. After controlling for the effects of these factors we found strong evidence of an increasing trend for coyotes, a decreasing trend for gray foxes, and a decreasing, yet more variable, trend for red foxes.