Migratory songbirds are fickle breeders, especially since the marshes where they mate are flanked by shore homes, roaring BMWs and miles of pavement. As their habitats shrink, so does their ability to reproduce. U.S. Fish and Wildlife is on the case.
“Can we create the habitat they want? Can we attract them? This is the journey we are on. We’re taking the pulse of this site.” That’s Joe Smith, a wildlife biologist from the Villas who works for the U.S. Fish and Wildlife Service at Edwin B. Forsythe National Wildlife Refuge.
The “site” is the Cedar Bonnet Islands, a small slice of protected wetlands right by Long Beach Island, a place known by most for boardwalk booty shorts rather than shorebirds.
Joe and Kathryn Krueger, a seasonal biologist at the refuge, are here with knee-high wading boots and plenty of gear to see if they can find female specimens of an increasingly rare songbird, the saltmarsh sparrow. The presence of female saltmarsh sparrows would be a small sign that this protected land is hospitable enough for them to breed.
The Goal:
- Capture and tag saltmarsh sparrows
- Prove that compost material helps expand nesting habitat
- Do it all without harming the birds
The tools:
- Knee-high boots
- Mist nets designed in Japan
- Measuring devices like rulers and scales
- Small cloth bags that birds are put into so they can be weighed
- A full water bottle and snacks
The Cedar Bonnet Islands tell a story of two wetlands: one where the floor is made of natural material like compost, the other, just a few hundred feet away, that was created from sediment dredged up when a road was built nearby.
The Cedar Bonnet Islands tell a story of two wetlands: one where the floor is made of natural material like compost, the other, just a few hundred feet away, created with sediment dredged up to deepen the back bay network of channels used for boating.
Joe has a theory that the compost-filled area grows grass in the highest part of the marsh more easily, and thus attracts more nesting birds than a marsh created with dredge material alone.. It seems like a straightforward hypothesis, but proving it is the hard part.
The saltmarsh sparrow is a candidate for the endangered species list and can be elusive. Joe and Kathryn set up long metal posts connected by mist nets along the marsh. They trudge through mud and chat as they walk.
Birds that fly into the mist nets can be easily plucked out, measured, tagged and released. These special nets are invisible to birds and easily trap them unawares. They’re hard to buy, lest poachers and black-market pet salesmen use them for ill purposes.
Finding the saltmarsh sparrow is where things get tough. Kathryn and Joe approach the net from afar, starting behind low grasses where the birds often hide. They clap and holler to scare the birds into the net.
Success came fast but was a mirage. The first two birds caught by Joe and Kathryn look startlingly similar to saltmarsh sparrows, but no dice. The first was a seaside sparrow, similar in size, shape and color to the saltmarsh sparrow but with duller overall coloration. The second was close, but no cigar. It was a Nelson’s sparrow, with a slightly smaller bill, fewer streaks on its stomach and duller mustard coloration.
The species are differentiated for important reasons, like mating behaviors.
Joe said: “Most songbirds are kinda monogamous, they have a mated pair and a territory they defend. These <saltmarsh sparrow> guys aren’t like that. It’s just a lot of mating males swarming around the females. The males don’t provide any parental care to my knowledge.”
Joe takes gentle care of the birds he measures and tags. He and Kathryn take several measurements: beak tip to skull, the length of its tarsus (similar to an ankle) and weight, among other measurements. Birds are placed briefly into cloth bags and weighed. Joe holds them in a careful “bander’s grip,” legs held between his index and middle fingers.
“A lesson I follow is: Never inconvenience the bird, to the best of your ability,” Joe said. He knows the work is stressful for them, but it’s necessary if their species is to survive long term.
At last, the duo finds a female saltmarsh sparrow. It’s a spark of hope. It means that the habitat here is viable for this bird that has lost so much of its breeding grounds to development.
Joe is hopeful that compost material can be introduced to nearby habitats so that grasses will grow faster and more songbirds will mate. Habitats like the Cedar Bonnet Islands are teeming with life, even invisible life like the rare black rail, which runs around on the ground like a mammal.
The work of U.S. Fish and Wildlife biologists keeps land like this healthy, protected and diverse. But the work requires constant monitoring, and with humans so close by, the threat of fast change that animals can’t adapt to is ever-present.
“I don’t know what a random person thinks about the swamp marsh like this, one they just drive past. But it’s full of all this unique life, adapted to this specific place. It’s amazing,” Joe said.
Contact the author, Collin Hall, at 609-886-8600, ext. 156, or by email at chall@cmcherald.com.
