Feds marking habitat for endangered Rufa Red Knot consider much of Florida coast

Mary Helen Moore
The Daytona Beach News-Journal

More than 117,000 acres in Florida are set to be designated as critical wintering habitat for the rufa red knot — the first animal listed under the Endangered Species Act explicitly citing climate change as the primary threat, according to a U.S. Fish and Wildlife Service proposal.

Red knots, a robin-sized bird whose plumage turns red in the breeding season, fly thousands of miles per year on their annual migration route, one of the longest known. 

"For a little bird that weighs about 6½ to 7 ounces, that’s a pretty hefty trip," said David Hartgrove, president and conservation chair of Halifax River Audubon.

"They're a really special bird," said Marianne Korosy, the director of bird conservation for Audubon Florida

Limits on horseshoe crab harvests have helped stabilize red knot populations, but they have not yet started to rebound, worrying researchers.

In 2015, the bird was listed under the Endangered Species Act, primarily threatened by sea level rise, disasters and human disturbance. Whenever that happens, federal agencies must create a recovery plan and designate a critical habitat.

USFWS is in the midst of doing both.

For the red knot, USFWS proposed nearly 650,000 acres of coastline along the Eastern Seaboard from Massachusetts to Florida, sweeping along the Gulf Coast all the way to Texas.

In central Florida, the 27,000 acres extend from Ormond Beach to Merritt Island, overlapping with federally designated critical habitat for the piping plover, a threatened shorebird.

USFWS reports there are "a high concentration of rufa red knots during the winter" here.

A crowd of red knots on the Delaware shore.

"The main reason that area is so important to shorebirds is it provides the exact feeding regimen that they need," Hartgrove said. "Especially if they can be left alone. Unfortunately that doesn’t happen a lot."

That's where individuals can play their role in conservation. Khorosy said it's important to avoid flushing flocks of birds.

"They need to conserve their energy and maintain their body fat," she said.

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Climate change, horseshoe crabs decimate population

Red knots breed in the high Arctic and the islands of northernmost Canada, then make the trek south. It's a longer flight for some than it is for others.

"Some of the population migrates all the way to Tierra del Fuego at the tip of South America and some of the population winters on the Gulf Coast in the South Atlantic of the United States," Khorosy said. "So there's two different wintering populations."

"They tend to migrate right along the coast," Hartgrove said. "They’ll fly maybe 40 to 50 miles in the night, drop down on a beach somewhere. In some cases, they may hang out in an area for several weeks, depending on how good the feeding is."

A red knot in on Braddock Bay in New York.

How migratory birds like the red knot are able to return to the same sites with precision is still somewhat of a mystery. Khorosy has studied it herself in grassland sparrows. She said there's some evidence of a genetic component, given young birds sometimes make their first migrations without their parents.

"Neurologically, they memorize flights: what direction to fly and how long to fly. That becomes embedded in their brains," she explained.

This site fidelity, as researchers call it, makes red knots particularly vulnerable to climate change. In the high arctic where they breed, there's a narrow window where it's warm enough that red knots can find enough food to survive. As weather patterns grow more extreme, the long-distance migrants have a greater chance of being caught up in storms.

Then there's the food source — red knots are celebrated springtime visitors in the Delaware Bay, where they arrive just in time to feed on horseshoe crab eggs.

"This is where there’s a vulnerability to climate change because water temperatures can affect when horseshoe crabs lay their eggs," Khorosy said.

Endangered red knots feast on horseshoe crab eggs along the Delaware Bayshore each May.

Depending on this food source has gotten the birds in trouble before.

Hartgrove said researchers first noticed the population dwindling in the mid-1980s when fishers in the Delaware Bay turning to horseshoe crabs after overfishing other fish stocks.

"They were catching massive amounts of horseshoe crabs and just caused a massive crash in the population," Hartgrove said. "Then we started to see a crash in the red knot population."

Researchers banded red knots with leg flags for more than a decade after the population crash, and a birder accompanying Hartgrove during the 2006 North American Migration Count captured a photo of a red knot tagged 085.

Six years later, on a birding trip in Merritt Island, Hartgrove scoped a bird on a mud flat and snapped a photo with his phone. A few days later, he sat down to type in the bird's information.

"I'm thinking, '085, boy that sounds familiar.' I turn and look above my desk and there he was in that photo," Hartgrove recounted. "My guess is that bird has long since passed away, but I sure do look out for it every time I go out."

What does designating a critical habitat mean?

Designating areas as critical habitat does not establish a refuge or sanctuary, but it does require federal agencies and anyone in need of a federal permit, license, or funding to consult with the agency if their activities could affect the protected species.

Audubon Florida has provided USFWS with data from their staff's year-round surveys and Khorosy said she's happy the critical habitat proposed incorporates clusters of sites, including mud flats where red knots forage when the tide is low, and the higher places where they roost.

"It reflects our data," she said. 

The proposed habitat on the Atlantic Coast includes most of Volusia and Brevard counties. Nassau Sound, outside of Jacksonville, also made the list.

The remaining islands and beaches all are along the Gulf of Mexico.

They start in the Naples area, stretching from Ten Thousand Islands to north of Tampa Bay. There's the massive Cedar Keys complex a bit north, and the remainder lie within the Big Bend region, from St. Marks to Port St. Joe.

The USFWS will host an informational meeting on designating critical habitat for the red knot via Zoom at 6 p.m. Aug. 18. A public hearing is set to follow at 7:30 p.m. To register, visit fws.gov/​northeast/​red-knot/​.

The agency is gathering public comment until Sept. 13. To submit comment online, visit regulations.gov and search for rule number FWS-R5-ES-2021-0032.