Sampling the snowy plover song
A snowy plover with a broken wing cheeped to her chicks at Monterey Bay Aquarium’s wild bird rehabilitation facility.
The tiny bird’s high-pitched, staccato trills gave Aimee Greenebaum, the Aquarium’s curator of aviculture, an idea. That night, her colleagues tiptoed into the plover’s room with a microphone and recorded her peeps.
“It was a total whim,” Aimee says.
Ten years later, her team is still playing those plover-mama calls from a boom box—to coax eggs into hatching, and to soothe orphaned chicks.
The Aquarium is a rehabilitation site for the Western snowy plover, a shorebird listed as threatened under the Endangered Species Act.
During breeding season, Aimee’s team works with local parks and conservation groups to rescue and release injured snowy plovers and abandoned chicks. The collaboration has helped grow a healthy breeding population in Monterey Bay.
The problem for wild plovers
The Pacific population of Western snowy plovers has been federally listed as threatened since 1993. From southern Washington state to Baja California, coastal development has destroyed much of their breeding grounds.
“A lot of the habitat has been lost, and it’s not coming back,” says Kriss Neuman, waterbird ecologist with the conservation group Point Blue. “Monterey Bay’s undeveloped sandy shoreline is really important to plovers.”
From March through September, snowy plover pairs scurry along Monterey Bay beaches, laying their eggs in the sand and mudflats. Point Blue has monitored plover nests along California’s Central Coast for over 30 years.
State and federal agencies have roped off plover breeding areas and banned dogs on the beach, but dangers still lurk for these tiny birds. Crows and ravens can destroy their eggs, and beachgoers can scare plover parents into abandoning their chicks.
Since 2000, the Aquarium has released over 130 Western snowy plovers, 84 of which hatched in its rescue center. A 2013 study, which Kriss co-authored, found the Aquarium-reared birds were as successful at breeding as their wild counterparts.
“This species needs all the help we can give it,” says Senior Aviculturist Kimberly Fukuda. “Raising them to be released, and helping the population recover in the wild, is the most rewarding part of our rehab program.”
How to hatch a plover
The first step in hatching a snowy plover is to make sure the chick is alive, says Aviculturist Eric Miller. He takes the tiny egg into a dark room and shines a light beam onto the shell. If the egg is viable, he can see blood pumping through the veins of even the smallest embryo.
Then he pops the egg into an incubator—a metal box that can be controlled for temperature, humidity and movement—and waits for it to hatch.
Every snowy plover fetus develops a tiny, rhino-like horn on the end of its beak. The so-called “egg tooth” is
its ticket to freedom. First, the chick pierces a thin membrane sealing a pocket of air at the fat end of the egg. This causes oxygen to flow into the liquid yolk, allowing the baby bird to breathe for the first time.
Each breath drains the limited air supply inside the yolk, until the chick’s lack of oxygen causes muscle contractions. Meanwhile, the plover’s egg tooth slices through the shell like a can opener.
“The muscle spasms force the body against the shell, and eventually the chick just blows out of the egg,” Eric says. “Then we give it time to recover from being hatched. It looks stressful.”
Feather-duster foster parents
For the plover chicks that hatch at the Aquarium, our aviculture team introduces an adult plover from the Sandy Shore aviary exhibit. These foster parents tolerate the chicks more than parent them, Aimee says, but the babies love the company.
Plovers that hatched in the wild, but are in need of special care, are isolated to prevent spreading any diseases. For them, the rehab team gets creative. In lieu of an adult plover, they put a mirror and a feather duster with the chicks. The mirror gives them the comforting sense that another plover is with them. And the feather duster gives them a refuge of brown feathers to retreat into, like they might cuddle with a parent.
Aimee plays the recorded birdcalls to stimulate the unhatched chicks. She believes that the parents’ chirps motivate exhausted babies to keep breaking through the shell. Sometimes, the chicks even cheep back from inside. (Click below to hear the sound of the plover calls.)
“In the wild, the adults would be cheeping at them,” says Aimee. “I noticed if we play it, they’re like, ‘OK. I’m going to keep going.’”
Plovers keep a low profile
The Aquarium’s rehab facility is part of a successful conservation effort that has helped Monterey Bay plovers bounce back. In 2015, Point Blue counted 469 breeding plovers—more than three times the local breeding population in 1999.
Aimee hopes beachgoers learn to be sensitive of these skittish, endangered birds, which can be hard to notice. Don’t cross the ropes surrounding plover nesting areas, she advises. Pick up trash, which attracts crows, which in turn eat plover eggs. And please keep the dog on a leash, or at home.
If you do see a snowy plover in the wild, watch it quietly, and keep your distance. “Plovers are small, sandy-colored birds that blend in,” she says. “People don’t realize how close they are to them.”
Featured photo: Snowy plover chicks in the Aquarium’s rehabilitation facility. You can also see Western snowy plovers in our Sandy Shore aviary exhibit.