The origin, connectivity, and individual specialization of island wolves after deer extirpation

A wolf pack discovered on Pleasant Island in Southeast Alaska, USA defies
the assumed obligate relationship between wolves and ungulates by
persisting on sea otters and other marine prey after causing the local
extirpation of deer. This pack is also subjected to additive anthropogenic
sources of mortality in apparent isolation from other wolves. We used
molecular methods to determine the origin of Pleasant Island wolves and
ask how they persist under these circumstances. We applied DNA
metabarcoding and genotyping by amplicon sequencing with a novel SNP panel
to quantify variation in marine foraging behavior within packs, among
sexes, and individuals using 957 scats collected from the island and the
adjacent mainland from 2016-2022. We additionally used tissue samples to
quantify relatedness and gene flow with reduced representation sequencing.
Male, female, and individual island wolves all consistently consumed sea
otter (63.2% wPOO). In contrast, mainland wolves fed on ungulates (51.8%),
voles (19.5%), and sea otters to a lesser extent (14.3%) with more
variation annually, among sexes and individuals, indicating both
individual variation in the diet of a cooperatively hunting predator and
varying hunting strategies among individuals within the same pack. We also
found limited dispersal to and from the island with only one unrelated
wolf coming from the mainland during the six-year study period. Our
findings suggest wolves are more flexible in their foraging strategies
than is commonly appreciated and that the recolonization of sea otters can
allow wolves to persist on predominantly non-ungulate, marine resources.
Nevertheless, anthropogenic and natural mortality, and a lack of movement
to and from the island may threaten the continued persistence of the
Pleasant Island wolves.