Acorn Years: Squirrels in a City Park Through the Seasons

The Squirrels of Larchmont Park

1Larchmont Park covers 40 hectares in the middle of a busy city. Its north end is a grove of old oak trees, and its south end is a sunny meadow with a few maples and only scattered oaks. Eastern gray squirrels live in both parts of the park. Seventh grader Ines Wojcik joined the park's youth naturalist program last fall and worked with the park naturalist, Ms. Paloma Restrepo, to study them.

2In fall, gray squirrels eat acorns and bury many more, one at a time, all over their home area. Through the winter, when few other foods are around, they dig up buried acorns to eat. Most young squirrels are born in late winter and spring and leave the nest in summer. In spring and summer, squirrels also eat tree buds and flowers, seeds, mushrooms and some insects.

3Oak trees do not make the same number of acorns every year. Some years bring a huge crop, and other years very few. Since 2017, park staff have weighed the acorns that fall under ten marked oaks each fall and found the average mass per tree. The next summer, they count the young squirrels in the park and report the number per hectare. The graph shows each fall's acorn crop paired with the young counted the summer after it. The label on each dot is the year of the acorn crop, so the dot marked 17 shows the fall 2017 crop and the young counted in summer 2018.

4After a fall 2024 crop of about 10 kg per tree, Ines and Ms. Restrepo surveyed both ends of the park in each season. They counted the acorns on the ground in marked squares, and they weighed squirrels that wandered into padded live traps baited with peanuts before letting them go. In spring, they also checked whether ten adult females at each end were nursing young (Table 1 in Section 2).