Keeping tabs on the osprey population in New Jersey
By Ben Wurst, Habitat Program Manager
Over the past few weeks volunteers and biologists have been performing ground surveys to help determine the health of the osprey population in New Jersey. The surveys are part of the NJ Division of Fish and Wildlife, Endangered and Nongame Species Program, Osprey Management Project. Ospreys are listed as a threatened species in New Jersey. They were originally listed as endangered in 1974 after only 50 nesting pairs were found in 1973. By 1986, their status was upgraded to threatened after their population rebounded to 100 nesting pairs. Today there are over 450 pairs of ospreys that we help to monitor in New Jersey.
Ospreys are highly dependent upon humans to provide artificial nesting structures for them and they are highly susceptible to many different heavy metals and persistent organic pollutants like DDT, DDE, PCBs and more recently brominated fire retardants (PBDE) that bio-accumulate in the food chain.
Surveys are performed each year during summer when osprey nestlings are old enough to band (3-6 weeks old) but not old enough to fly. They cover all major nesting areas including, the Delaware Bay, Raritan Bay south to Cape May, and inland. During ground surveys nestlings are banded with USGS aluminum leg bands for future tracking. I survey areas from Great Bay in Little Egg Harbor north to Fort Monmouth in Oceanport and Mantoloking along the Atlantic Coast.
The data we collect (whether or not a nest is active and the # of young produced) is used to calculate the productivity rate. Ospreys need a productivity rate of at least .8 young/nest to sustain the population. In the past 5+ years they have had more than double this rate. The population has grown by 21% from 2006 to 2009. Last year there were 485 nesting pairs in New Jersey. This year we expect there to be even more. Last years results are summarized in the 2009 Newsletter.
Last year was a record-breaking year. Before the effects of DDT, habitat loss and persecution decimated the population in the mid-1900’s there were over 500 nesting pairs. Since the mid-1970’s, when the project began the population has slowly risen to its current level. Each year more platforms are damaged by harsh winter weather and the extremes of being located in saltmarshes. Work is continual and never ending. Repairs to existing platforms occur during the “off” season or non-breeding season from late August to the end of March. New platforms (built with stainless and galvanized hardware, that are meant to last) are placed in areas where suitable habitat exists where little to no available nest sites occur. It is our goal to help the population recover to historic numbers.
Preliminary results show that some areas fared very well this year. The colony from Little Egg Harbor to Atlantic City had 25 active nests that produced 57 young. Last year, 36 nests produced 55 young. The climate has been optimal for ospreys, except for the occasional thunderstorm with high winds. Temperatures have been above normal and precipitation has been below normal. Full results from the season will be available this fall once the survey results are collected and summarized.
Our work would not be possible without the support of our members and volunteers. Thank you!