Gray squirrels breed twice in a year. Locally, they have their first litter in February. Nest building begins after most leaves have fallen. Some squirrels will nest in tree hollows, but most seem to prefer to build a drey, or leaf nest, in the forks of trees. Nests are not haphazardly built anywhere, but appear to be constructed at carefully chosen sites.
In the active nest shown here, the squirrel has chosen a heavy limb, giving it a strong floor. If you look closely, you can see that there are also small branches that the nest has either been built around or perhaps have even been incorporated into the structure. These branches help the nest remain securely in place in the high winds common at this time of year.