Archive for July 2016

Horseshoe Crab Monitoring 2016 Recap and Results

NYC Audubon Conservation Biologist Debra Kriensky breaks down the horseshoe crab numbers from this year’s monitoring efforts in Jamaica Bay

 

Horseshoe Crabs Photo by NYC Audubon

Photo: NYC Audubuon

We are happy to report that 2016 was a great year for horseshoe crabs in Jamaica Bay!

 

New York City Audubon once again ventured out during the new and full moons in May and June to count and tag spawning horseshoe crabs. This was our eighth year collecting data on horseshoe crabs in Jamaica Bay, part of a larger project run by the New York State Department of Environmental Conservation and Cornell University Cooperative Extension.

 

In 2015, a colder than usual spring resulted in unusually low counts at some of our beaches, such as Plumb Beach East. This year, however, the shores were full of mating horseshoe crabs and our counts indicate that numbers continue to stay relatively stable in Jamaica Bay. This is great news, given how important horseshoe crab eggs are to the migratory shorebirds that come through New York City each spring on their way north.

 

With the help of 163 volunteers (a record!), we were able to count spawning horseshoe crabs at four locations: Plumb Beach East, Plumb Beach West, Big Egg Marsh, and Dead Horse Bay. Spawning activity peaked during the full moon around Memorial Day this year. The high counts were 205 crabs at Plumb Beach East, 21 crabs at Plumb Beach West, and 451 crabs at Big Egg (and that was only what we counted in our quadrat samples!). At Dead Horse Bay, where we take a total count of the horseshoe crabs, the high count was 493.

Volunteers Counting Horseshoe Crabs, Photo by Tracy Pennoyer

Volunteers Counting Horseshoe Crabs, Photo by Tracy Pennoyer

We were able to tag 797 crabs this year, making a total of 4,380 horseshoe crabs tagged since we started in 2009. We had 78 re-sightings of tagged crabs this year – 55 of which were tagged earlier in the spawning season, indicating that many of the horseshoe crabs we see stick around at the same beach for several nights and even weeks.

 

We also saw nine crabs we had tagged in 2015, two we had tagged in 2014, and one had tagged in 2013! In addition to all of these horseshoe crabs that are returning to the same beach night after night and year after year, we also saw 10 tagged crabs that were put out by other organizations. So far, we know that one was tagged last year in Cliffwood Beach, NJ and another was tagged in 2012 at Breezy Beach in the Rockaways. It will be interesting to eventually find out where and when the others were tagged.

 

If you ever spot a tagged horseshoe crab, write down the number and report where and when you found it to the U.S. Fish & Wildlife Service here.

Tagged Horseshoe Crab Photo by NYC Audubon

Horseshoe Crab Tagged "341401"

Thank you to all the amazing volunteers who came out to count with us this year, especially our dedicated volunteer site coordinators, who make it all possible! We’re also very thankful to Patagonia, the Williams Companies, and Investors Bank Foundation for their generous support of this year’s horseshoe crab and shorebird work.

 

We’re already excited for next year’s spawning season! We hope to have another record number of volunteers for next year’s counts. Please email volunteer@nycaudubon.org if you are interested in getting involved in this important (and fun!) citizen science study.

 

New York City’s Common Terns

Common Tern and Chick on Governors Island © Barbara Saunders

Common Tern and Chick on Governors Island © Barbara Saunders

NYC Audubon Director of Conservation and Science Susan Elbin reports on our work with the New York State threatened Common Tern:

 

The common tern (Sterna hirundo), a native North American waterbird, was nearly extirpated from North America by the millinery trade in the late 19th century, and again by habitat loss and environmental contaminants in the mid-20th century. Thanks to the Migratory Bird Treaty Act and other conservation efforts and environmental regulations, this species has been brought back from the brink of extinction. But populations have not returned to historic levels. The common tern continues to be a threatened species in New York State, and maintaining current population levels requires management to protect the breeding population. The major threats to tern populations on their breeding grounds appear to be space limitation due to habitat destruction and competition with other waterbirds. Common terns are also threatened by specific consequences of climate changes such as warmer summers and severe storms that impact shoreline nesting areas.

 

Common terns have been nesting in the Jamaica Bay area for decades. Just recently, a colony has established itself on the decommissioned piers of Governors Island. Just a ferry ride from lower Manhattan, the birds can been seen plunge-diving for fish to feed their growing chicks.

 

While the majority of our conservation and monitoring efforts occurs during the breeding season, common terns spend less than one-third of the year on their breeding grounds. Threats during the other two-thirds of the year, during migration and wintering periods, are unknown. We have initiated two pilot studies using high-technology techniques: geolocators and nanotags. A geolocator is a tag that the bird wears around its leg. The tag can later be removed from the bird in order to download latitude/longitude data collected over the course of one year. Nanotags are small radio transmitters attached to a bird’s back that send a signal to stationary VHF towers installed along the eastern seaboard of the U.S. and across Canada. Results from these two projects will indicate where the birds have spent the winter and how long they stay in a given area, respectively. The goal is to determine what areas New York City common terns are using as stopover sites during migration and over the winter. We plan to expand this project in the coming years, working with partner organizations to increase the sample size and to collect more data about the trends in migratory and overwintering behavior as well as the amount of variation in this behavior within the population. Determining where these birds migrate and overwinter is the necessary first step in identifying threats to the population during these times of the year, when the majority of mortality likely takes place.

 

Join us for the “It’s Your Tern” festival on Governors Island this Saturday, July 16! Learn more here.