The flight of the red knot

The flight of the red knot
Researchers study why population is declining

11:16 PM, May 18, 2012
Written by
The News Journal

The brain trust of Delaware’s shorebird research project is in a converted garage on the ground floor of a bayfront beach house.

Here a bank of computers allows scientists – many of whom are here specifically to study the population shifts in red knot shorebirds – to access available information on any bird they have previously captured and tagged.

There have been thousands over the last decade – birds captured and tagged in South America, along the Delaware Bay and even some captured in the Canadian Arctic. They are marked with distinct, colored-coded and numbered leg bands. Each bird that is tagged has a history – its own story of survival.

“We can have three people entering data at the same time,” said Kevin Kalasz, the state’s non-game wildlife biologist and coordinator of the shorebird research project.

Time is critical because many shorebird species have been in a population decline. Numbers of red knots, robin-sized birds and one of the longest distance migrants to Delaware Bay, have dropped so dramatically in the last decade that in 2006 they were named a candidate for the endangered species list. A decision is expected sometime later this year.

With the remote data entry and computers, the research team that includes scientists from England, Canada, South American and the United States, can spot a bird and immediately call up its history, with details on where it was first banded, any subsequent catches and how it is doing.

Over the years, scientists have concluded that the Delaware Bay stopover plays a critical role in the health of the red knot population. Its success in breeding when it reaches Canada seems directly linked to the available food supply – specifically horseshoe crab eggs – along the Delaware and New Jersey shores of the bay.

“We’re really trying to understand how shorebirds are doing in the bay,” Kalasz said.

The great unknown is the plight of juvenile red knots between the time they leave the Canadian Arctic and when they return to Delaware Bay two years later, Kalasz said.

Last summer’s breeding season produced high numbers of juvenile birds, Kalasz said.

The concern is whether something happens to these birds – food supplies, hunting, habitat loss – in South America before they reach maturity and make their first breeding trip north through Delaware Bay, he said.

Scientists aren’t detecting any increases in the red knot population even though the numbers of juveniles in Canada – at least last year – was good.

“We don’t have a very good idea,” he said.

Adult shorebirds began arriving along Delaware Bay last week and their numbers will continue to build for another week or so.

These birds stop in Delaware to eat horseshoe crab eggs each year to make the flight to Canada. With the decrease in the amount of food for these birds, less are able to make the long journey. This also connects with the other thread on the grasses, as the storms & floods last summer & fall will impact the birds by significantly reducing the food available for the flocks. I have witnessed the wonderful sight of these in years past at Bombay hook park, it is a sight to behold when thousands of these arrive.