A group of intrepid hawk watchers perched themselves atop Bradbury Mountain in Pownal on Saturday. Armed with binoculars, they helped collect data to aid in conserving several species of raptors.

The spring hawk watch season at Bradbury Mountain State Park runs from mid-March to mid-May.

The hawk watch was founded and co-sponsored by Freeport Wild Bird Supply. “We are the only full-season spring counters in New England,” said Derek Lovitch, who co-owns the store with his wife, Jeannette.

Lovitch, who led Saturday’s watch, said a hawk watch is also a great social event, adding that he and Jeannette met at such an event.

The watch has collected data on hawk migration for 10 years, and this year’s official counter is North Yarmouth resident and longtime hawk watch volunteer Zane Baker.

The data collected, Lovitch explained, is a small piece in a larger puzzle of observation to help identify trends in species numbers. Each day, numbers are submitted to hawkcount.org.

Lovitch said bird counting in the last century raised a red flag to the decline in osprey and other bird populations that led to studies finding the pesticide DDT was poisoning avian populations. This work led to protections, namely the ban of DDT and the Endangered Specifies Act of 1973.

The data collected this year will be a piece of the puzzle to determine migration trends. Today, there is a hypothesis that hawk populations are not traveling as far south during migration, a phenomenon known as short-stopping, which could be an effect of climate change, Lovitch said.

On average more than 1,500 broad wing hawks, 400 osprey, and 75 bald eagles pass through the park on their way north. Lovitch said there are less raptors to count in the spring as compared to the fall migration, as 80 percent of juvenile hawks do not survive their first winter, because they experience difficulty in learning to hunt and finding food, as well as other dangers, like wind turbines and other hawks.

There are two hawk territories of birds that live at the park year-round, which have been identified by birders.

Last year, more than 1,000 people attended the hawk watch throughout the spring.