Ecological effects of a declining red wolf population

Abstract

AbstractCarnivores, especially wolves (Canis sp.), have profound impacts on their ecosystems, affecting the abundance and behavior of prey and competitors, but this has not been examined in detail for red wolves (C. rufus). We studied a population of red wolves that was reintroduced to eastern North Carolina in 1987 and initially thrived, peaking at 120 animals. Due to an increase in anthropogenic mortality and a decline in government support, the population experienced a crash starting in 2014. We evaluated changes in the relative abundance of prey and competitor species during the red wolf decline with 25 camera traps run primarily on National Wildlife Refuges from 2015 to 2021. If red wolves were having an ecological effect on the mammal community, we expected this effect would decline as the wolf population waned, resulting in increased prey and competitor populations. Supporting this, we found that relative abundance increased for most prey and competitor species including American black bear (Ursus americanus), bobcat (Lynx rufus), Virginia opossum (Didelphis virginiana) and Northern raccoon (Procyon lotor). For all species, this increase was most notable after spring 2018, the second year with low red wolf reproduction. For some species, the increase was dramatic; the detection rate for raccoon, bear and bobcat doubled from the spring of 2018 to the spring of 2021. White‐tailed deer (Odocoileus virginianus) showed a general increase in relative abundance but remained prevalent even at their lowest detection rates. Our results lend correlational support to the hypothesis that red wolves had a strong effect on their ecosystems by suppressing prey and competitor populations when they were at their peak. This study adds to the growing body of evidence that reintroductions of large predators have ecological impacts, with the caveat that these impacts can decline rapidly if the predators dwindle back to critically low numbers.