Ospreys, once an endangered species, surged in number since the nation banned the pesticide DDT in 1972. But last year, the bird’s presence in Connecticut soared to record highs, prompting the Connecticut Audubon Society to search for more volunteers than ever before to help monitor the rising population.

In Connecticut, where ospreys spend the spring and summer months, hundreds of volunteers are responsible for tallying and reporting on the local population, said Milan Bull, a senior director at the state’s Audubon Society. The organization works with the state Department of Energy and Environmental Protection to run the program Osprey Nation, which monitors over 600 nests with the help of 224 volunteers.

But right now, there are too many nests for the volunteers to keep up with. Tom Andersen, a director at the Connecticut Audubon Society, hopes that new volunteers can both cover nests that could not be reported on last year and discover new ones. From 2014 to 2016, the number of mapped nest locations increased from 414 to 606. At the same time, the number of stewards grew from 100 to 224.

“These are ordinary citizens going out there, maybe with a pair of binoculars, maybe without a pair, just going out there and seeing what’s going on,” said Brian Hess, a wildlife biologist at DEEP. “You don’t have to have any special skills to do this kind of thing and provide us with really good results.”

According to Bull, the program began in 2014, when the growing osprey population became too much for just DEEP to oversee. Ospreys, which used to live mostly in dead trees, also began nesting in more creative locations, such as cellphone towers and billboards.

With so many nests, having enough volunteers is crucial, Andersen said. Each steward monitors a nest, visiting it about every two weeks for about 15 minutes per visit. They then report on the number of adults, fledglings or baby birds and hatchlings or newborn birds. Volunteers will also leave notes describing how much fun they have, said Milan Bull, a senior director at the state Audubon Society.

Though many stewards are avid naturalists, advanced technical experience is not needed to help out as the birds are easy to observe, Andersen said.

The hawk-like birds are also important to observe because they can provide indicators of environmental conditions, such as water quality. Ospreys’ diets are composed almost exclusively of fish, and poor water quality can have devastating effects on the population. Ospreys that have consumed too much DDT lay soft eggs, which give the chicks inside very little chance of survival.

The increase in osprey population is a good sign for water quality in the region. Once found primarily around the eastern coast of Connecticut, ospreys have expanded inland along rivers as their numbers have increased.

The birds are also an early warning system for environmental changes. If the population were to drop sharply, scientists would know that something ominous were happening in the environment.

“[Ospreys] are our canary in the coal mine, our sentinel,” said Brian Hess, a wildlife biologist at DEEP.

Ospreys that live on the coast rely primarily on menhaden, a saltwater fish. According to Bull, the fishing industry is pushing hard to expand the commercial fishing of menhaden. Though ospreys are opportunistic birds and will eat any fish they can catch, a decreasing menhaden population could have a dire effect on the ospreys, he added.

Right now, the ospreys that will soon be in Connecticut are currently in Central American and the Caribbean waiting for winter to end in the northern hemisphere. But soon, they will be back, and they will need to be counted.

Osprey Nation will hold training sessions on Feb. 18 at the Essex Public Library and on Feb. 25 at the Milford Point Coastal Center from 10 a.m. to 12 p.m.