American oystercatchers are on the way back

 

This article was originally published in the Delaware News Journal on January 24, 2014 and was written by Molly Murray. View the original article here.


Populations of American oystercatcher shorebirds appear to have stabilized and started to increase on the Atlantic and Gulf coasts after a coordinated, five-year restoration effort by conservation groups and state agencies.

 

In Delaware, the numbers appear to be stable with about 15 nesting pairs over the last four years, said Matthew Bailey, a state wildlife biologist.

 

The downside: Delaware has seen limited production of young birds from those nesting pairs, he said.

 

For instance, just two young birds survived the nesting season to fledge last year. In 2010, 10 young birds fledged, he said.

 

But even those numbers are part of a bigger success story.

 

In Delaware’s last breeding bird survey – done from 1983 to 1987 – there were seven possible nesting pairs in the state and only three of those were confirmed. And the book Birds of Delaware described them as “unknown in Delaware at the beginning of the 20th Century.”

 

The birds at one time probably ranged from Labrador and Newfoundland in Canada south to Florida and into the Gulf of Mexico. But during the 1800s they were targeted by market hunters who went after both the adult birds and their eggs. The birds were extirpated along the Atlantic Coast, according to a 2007 U.S. Fish & Wildlife Survey report.

 

The Migratory Bird Treaty Act of 1918 put an end to market hunting and the population stated to rebound especially along the Virginia and North Carolina coasts.

 

In 2002-2003, scientists from Manomet did a coast-wide survey and estimated a population of nearly 10,900 birds.

 

“The numbers have been dropping since the early 2000s but we don’t know exactly when the decline began,” said Shiloh Schulte, a scientist at the Manomet Center and coordinator of the American Oystercatcher Working Group.

 

By 2009, the estimated population was down to 10,000 birds so that summer, the working group was formed, he said. The coalition included 35 groups from Canada to Texas. The Delaware Division of Fish & Wildlife was one of those partners.

 

A most-recent aerial survey from Long Island to the Mexico border, covered more than 9,000 miles and was completed last fall. Total estimated bird count: 11,200.

 

“This kind of conservation success is extraordinary, especially in the shorebird world,” Schulte said. “This was a targeted and coordinated approach to conservation involving 35 organizations, federal, state and private. We were hoping to see some signs of recovery with this survey, but the results show the population has already exceeded the 2003 mark.”

 

Along areas impacted by Hurricane Sandy, some traditional beach nesting areas were devastated but new areas were created, according to a report to the Working Group last month.

 

In New Jersey, the survey numbers were down from the estimated 1,000 birds in 2003 to around 250 in the 2013 survey. But those numbers may not indicate population health in the state because some birds had already started moving south at the time of the 2013 survey.

 

No birds were recorded in either the 2003 or 2013 survey for Maryland.

 

The states with the largest population gains: Virginia, North Carolina, Georgia and Florida.

 

Here in Delaware – and through the rest of their range – the birds favor coastal areas for nesting because they feed on bivalves and marine invertebrates.

 

Bailey said that birds nest both along the Delaware Bay and the Atlantic Coast, carving a shallow scrap in the sand to lay their eggs.

 

Because the nesting areas are attached to mainland areas, the nests are especially vulnerable to predation from foxes and other mammals, he said.

 

The birds are the largest of the shorebirds and state officials can’t use enclosures to keep predators out like they do with piping plovers, Bailey said. Any opening to let the larger oyster catchers come and go to feed would be big enough to let predators in, too, he said.

 

The best nesting successes have come on remote islands in Rehoboth and Indian River bays, he said.

 

There, predators aren’t an issue. But high tides are.

 

Last year, for instance, several nests were lost in abnormally high tides in May, he said.

 

The tides weren’t the result of coastal storms, Bailey said. Instead, they were seasonal, lunar high tides.

 

Among the concerns in Delaware and throughout the region is how rising sea levels will impact nesting areas.

 

Bailey said that if a nest is washed away and the eggs haven’t yet hatched, the adults will typically try again. But if young birds are washed away, the pair is done for the season, he said.

 

It takes about 35 days from the time a baby oystercatcher hatches until it flies, and during that time, and often beyond, they are dependent upon their parents for food.

 

“The challenge we have in Delaware is with our productivity,” Bailey said.