While many species of wildlife can be seen at Skinner, it is the birds that attract the most attention. Long a favorite of birdwatchers and hawk watchers, the park has several species of interest. The Cerulean Warbler and Worm-eating Warbler are rare in Massachusetts and their numbers are declining across the country. Both have been regularly seen along the park road. Indigo Buntings are frequently seen from the porch of the Summit House. Common Ravens and Bald Eagles can also be seen soaring along the ridge.
The Summit House is one of the finest spots to observe hawks migrating in the fall. The Mt. Holyoke Range and Mt. Tom Range capture surface winds and creates updrafts on which hawks ride. When the wind blows from the northwest, hawks can be seen gliding and soaring above Skinner State Park. The Connecticut River, which runs southward from the watershed dividing Canada from northern New Hampshire, provides the most direct and easily followed route for the birds to migrate.
Hawk migration begins in mid-September and continues through November with different species moving through at different times. First come large flights of Broad-winged Hawks: it is not unusual to see several thousand birds pass the Summit House. A steady northwest wind gives the hawks a tail wind and sunny skies warm the earth, creating rising currents of air or thermals. The soaring hawks rise up on the thermals and then glide to the next thermal, which enables them to travel many miles without flapping their wings.
As well as Broad-winged Hawks, Red-tailed and Red-shouldered Hawks can be seen migrating past the Summit House. Three species of accipiters, or true hawks, which can be recognized by their long tails and broad stout wings, are also often seen: Sharp-shinned Hawk, Coopers Hawk, and the Northern Goshawk. Peregrine Falcons and occasional Northern Harriers have been spotted by hawk watchers on Mt Holyoke.