In 2016, two studies compared the DNA sequences of 42,000 single nucleotide polymorphisms in North American gray wolves and found the coastal wolves to be genetically and phenotypically distinct from other wolves. They share the same habitat and prey species, and form one of the study's 6 identified ecotypes - a genetically and ecologically distinct population separated from other populations by their different type of habitat. The local adaptation of a wolf ecotype most likely reflects the wolf's preference to remain in the type of habitat that it was born into. Wolves that prey on fish and small deer in wet, coastal environments tend to be smaller than other wolves.