Osprey Successes & Failures
Osprey nests failed this year – and at an alarming rate. More than half of 100 nests checked during a July survey produced no young.
That didn’t happen in Connecticut though. It was on the Patuxent River, one of the major tributaries of Chesapeake Bay in Maryland.
It’s not clear what has befallen these fish-eating birds of prey to our south. But one thing we are sure of: nothing similar is happening to the 454 Osprey nests in Connecticut.
We know this because of the steady stream of data and observations sent in by the 287 stewards who are volunteering for Connecticut Audubon’s Osprey Nation citizen science project.
The failure rate of the Patuxent River Osprey nests – discovered during a boat survey in July – is more than twice as high as wildlife officials in Maryland had expected. Although they are not sure of the cause, they think that an unusually cold May might have resulted in fewer eggs hatching successfully. They say however that more work needs to be done to pin that down.
Here in Connecticut, Osprey Nation stewards began sending in reports of nestlings in June, so by late June and into mid-July we had a clear idea that success rates were probably going to be good.
By the end of the season, we knew from our stewards’ data that there were 394 successful Osprey nests in Connecticut and 60 that had failed or been abandoned – a success rate of 87%. The data submitted by the volunteer stewards in 2015 and 2016 show success rates of 80% and 91.5%.
For now we’re comfortable with that range. But we need many more years of data to determine what rate is sustainable.
The beauty of Osprey nation is that our corps of dedicated volunteers is set up to determine exactly that.
If we had seen a drop-off similar to Maryland’s, we would have reported it to the state Department of Energy and Environmental Protection and to experts such as our colleague Paul Spitzer, who has been studying Ospreys since the 1970s. We would have asked the stewards if they had seen any obvious causes. We would have tried to determine if nearby areas such as Rhode Island and Long Island were experiencing the same thing. We would have made our findings public, to our members and to the media. And we would be extra vigilant the following year.
You probably know that following World War II, the populations of Ospreys, Bald Eagles, Peregrine Falcons and other avian predators plummeted, some to the brink of extinction. Scientists searched for the reason and found that the pesticide DDT was the cause. That led to a ban on DDT.
Years of work by government agencies, conservation organizations, and volunteers resulted in a rebound and now each of those species is relatively safe.
We’re seeing the benefit of that in Connecticut now. But we’re also watching for the future. The volunteers of Osprey Nation volunteers are our eyes and ears.
Osprey Nation Background Information
Osprey Nation is Connecticut Audubon Society’s citizen science partnership, launched in the summer of 2014, to monitor the health of our state’s Ospreys. The goal of Osprey Nation is to create a long-term record of data that will give the conservation community a better understanding of the health of Connecticut’s Osprey population.
In its first season, Osprey Nation’s 100-plus stewards located 414 nests in five counties and 42 towns, and monitored 174 of those nests. We plotted all the nests and the data submitted by the stewards on the map below. Osprey Nation stewards confirmed that 78 young Ospreys were successfully fledged in 2014, a number that we’re confident is low.
In its second year, the program saw a rise in the number of volunteer stewards, to 146; in the number of nest locations added to the project’s interactive map, 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.
In its third year, we had 220 stewards sign up to monitor nests. By the end of the 2016 season, there were 606 nests plotted on the Osprey Nation map. Over 400 of these nests were active, and approximately 500 fledglings were reported this year!
The project is off to a great start but we still need your help and expertise!
Our network of Osprey Nation stewards collects and sends us data on the birds’ arrival dates each spring, the location of nests, nesting success and departure dates. We enter the data on a map for everyone to view. Osprey Nation is a partnership with the Connecticut Department of Energy and Environmental Protection and we will be submitting the data to DEEP biologists.
We also ask the stewards to monitor the condition of Osprey nesting sites, especially poles, and to work with Connecticut Audubon and the Connecticut DEEP to make sure they are safe and secure.
We are continuing to add nest locations to the Osprey Nation map. We are also looking for trends that would indicate whether the state’s Osprey population is declining or increasing, and what those trends might tell us about water quality and fish populations.
It was only several decades ago that the widespread use of DDT brought these great fish-eating raptors to the brink of extinction. But with a ban on this toxic pesticide and the efforts of government biologists, conservation groups and individuals, Ospreys have made a dramatic comeback.