As you follow the beginning of the red trail in Champlain North Open Space coming into the meadow, you'll see mounds of soil on both sides of the trail.
These are ant hills built by a Formica species, a classification of ants commonly called mound ants, wood ants or thatching ants.
Mound-building Formica can have a considerable effect on their environment, maintaining populations of aphids as a food source and preying on other insects, including tree pests such as eastern tent caterpillars. While the life expectancy of ants varies by species, some from the genus Formica can live for 15 years.
Formica nests vary in type but include excavations in soil that can create the large mounds as you see in the open space. These ant hills can be up to 3 to 4 feet wide and 2 feet tall.
They are often located in open areas like meadows. Of interest to hikers and visitors, Formica ants are diurnal (active during the daytime), so you can see them actively working around their mounds.
Be cautious and respectful around the anthills. While Formica do not sting, these ants can bite using strong mouth parts. They may also spray formic acid from the tips of their abdomens at predators or perceived threats (like human fingers).
Thanks to Wikipedia.