Report shows Connecticut's Osprey population thriving

Connecticut’s Osprey population, which numbers at least 250 active nests, is thriving and healthy, and in all likelihood indicates that local rivers, lakes and Long Island Sound are clean enough to support ample fish for Ospreys to feed on.

In addition, the fish seem to be free of toxins that would harm Ospreys and reduce their breeding success, as happened in the middle of the 20th century because of DDT.

Those are the key conclusions of the Connecticut Audubon Society’s Osprey Nation report for 2015, which the organization released today to mark the start of the citizen science monitoring program’s 2016 season, its third. The Ospreys that nest in Connecticut are migrating north now and will arrive later this month and in early April.

Click here for the Osprey Nation 2015 report.

“ ‘Canary in a coal mine’ is not just a metaphor. Birds tell us a great deal about what’s happening in the environment, and are often the first indicator of environmental problems,” said Milan Bull, Connecticut Audubon’s senior director of science and conservation. “In this case what they are telling us is good news. The Osprey population trend over recent decades is obviously up and the population looks to be healthy.

“The data our 146 Osprey Nation volunteer stewards are collecting will start to tell us over the next few years whether that upward trend is continuing.”

Connecticut Audubon staff coordinates the Osprey Nation volunteers, records data on an interactive map on the organization’s website, and shares the data with biologists at the Connecticut Department of Energy and Environmental Protection and other partners.

In its second year, the program saw a rise in the number of volunteer stewards, from 100 to 146; in the number of nest locations added to the project’s interactive map, from 414 to 515; in the number of active nests that were recorded, from 210 to 250; and the total number of hatchlings, from 221 to 415. Observers recorded that 356 of those hatchlings fledged.

Osprey Nation stewards found nests in every county except Tolland and in 56 of the state’s 169 towns.

The increases show that Osprey Nation is becoming more successful as a program, although they do not indicate – necessarily – that the number of Ospreys and nests rose by that much from 2014 to 2015.

The report states: “The increase in active nests and successful juveniles recorded in our 2014 and 2015 data reflects an increase in stewards rather than an increase in nest success: more people were looking for nests and recording information, so more nests were found and more data submitted.”

Osprey populations worldwide began to fall shortly after the introduction of DDT, a toxic organochlorine pesticide, in 1948, Ospreys and other birds that eat fish, such as Bald Eagles and Brown Pelicans, began experiencing serious population declines. DDT interfered with calcium deposition, which resulted in brittle eggs that broke during incubation.

DDT was banned in the United States in 1972, when Ospreys were at an all-time low. Only eight known nesting pairs were recorded in Connecticut in 1970.

However in Connecticut, the DDT ban and a citizen science volunteer effort led by the Connecticut Department of Environmental Protection, Roger Tory Peterson, Dr. Paul Spitzer, and others to build Osprey platforms and watch over nests resulted in a slow rebound.