The natural history and ecology of melanism in red wolf and coyote populations of the southeastern United States – evidence for Gloger’s rule, published in BMC Zoology on June 20, 2022, sheds light on melanistic canids that once ranged across the southeast. Researchers led by Dr. Joey Hinton of the Wolf Conservation Center used trapline captures, body measurements, GPS data, and mortality events to assess the occurrence, morphometrics, habitat selection, and survival of melanistic coyotes.

19th and early 20th-century accounts indicated that melanistic wolves made up ≥25% of the historical red wolf population. The phenotype is now extinct in extant red wolves but represents 5–8.5% of coyote and red wolf-coyote hybrids in the southeastern US who replaced wolves.

Was melanism correlated with body size and behaviors? No and yes. Researchers detected no correlation between color and size. Body size in canids increased with red wolf ancestry. So, red wolves > hybrids > coyotes. Melanism correlated well with habitat selection and space use behaviors.

Therefore, the findings support Gloger’s rule for coyotes by which melanistic animals exhibited stronger preferences for canopy cover and wetlands than did gray conspecifics; the same applied to roads. Gray coyotes preferred open cover and drier areas such as agriculture. Also, melanistic coyotes had larger home ranges (1.6x) than did gray conspecifics. This wasn’t surprising given their preference for woody wetlands. It’s lower quality habitat and likely forced melanistic coyotes to have larger territories to meet energetic demands.

In North Carolina, annual survival was greater for melanistic coyotes and hybrids than for gray conspecifics. This likely resulted from their use of woody wetland cover (dark environment) which improved concealment. So, why the low occurrence in the Southeast?

Habitat and larger territorial requirements could be a breeding constraint for melanistic coyotes that facilitates weak assortative mating. Dr. Hinton and team’s previous research reported differences in space use as a barrier to red wolf and coyote hybridization in NC, so that logic could be applied here.