Coywolf, <em>Canis latrans</em> × <em>lycaon</em>, Pack Density Doubles Following the Death of a Resident Territorial Male

We studied a subset of four radio-collared individuals that were a part of a larger study documenting Coywolf ( Canis latrans × lycaon ; Eastern Coyote) ecology in an urbanized landscape (Cape Cod, Massachusetts), and report on the territory of a typical sized pack that was subdivided roughly in half following the death of the breeding male from the original ("Centerville") pack. The original residents lived in a winter pack size (i.e., after pup/juvenile dispersal) of three or four individuals in a 19.66 km 2 territory and a density of 0.15-0.20 individuals/km 2 , as determined by radio-tracking and direct observations, with their territory bordering that of other monitored packs. Following the death of the breeding male, two other radio-collared Coywolves (a young male from the original Centerville pack and a young female from a bordering pack) shifted their respective territories to overlap the majority of the original Centerville pack's territory. These two groups were the same size as the original pack (three or four individuals each) but occupied smaller territories (5.28 km 2 and 12.70 km 2 ) within the previous pack's territory. The combined density for the two new packs was estimated at 0.33-0.45 individuals/km 2 or 2.2 times greater than the former pack's density and was 2.5 times (0.38-0.50 individuals/km 2 ) greater when accounting for the slight (12%) overlap between the territories of the two new packs. Our results suggest that local Coyote/Coywolf density (i.e., at the pack level) may increase following the death of the breeding male of a given pack, probably because of the reduced (or lack of) protection of territorial boundaries. This finding has particular relevance to Coyote/Coywolf management programs aimed at reducing local densities via removal of individuals from these populations. Further implications exist for enriching our understanding of the trophic dynamics of urbanized habitats.