On Exhibit: Sandy Shore & Aviary
Charadrius nivosus nivosus
small crustaceans, soft invertebrates and small insects
6 to 7 inches (15 to 18 cm)
killdeers; Family: Charadridae
tidal waters of the Pacific Ocean from Damon Point, Washington, to Bahia Magdelena, Baja California, Mexico
At the Aquarium
"People don't realize that they're bothering plovers because the birds hide so well," says Aimee Greenebaum, associate curator of aviculture. "They're kind of sandy-colored along their backs so they actually blend in very well with the sand—that's one of the problems."
As one of the main rehabilitation sites for shorebirds in northern California, the Aquarium works hard to make a difference to the threatened western snowy plover population. We collaborate with local and regional parks, avian conservation groups and local biologists to rescue injured adults, injured chicks and abandoned eggs. Our aviculture team treats the birds behind the scenes and also incubates the snowy plover eggs until they hatch. "The chicks start out in an ICU where it's kept really warm—around 99 degrees," Aimee says. When a chick is ready to hatch, the staff lends a little help by playing an audio recording of a female plover. The sound of the adult chirping can stimulate the chick to start pecking at the egg.
After they hatch, an adult snowy plover from the Sandy Shore & Aviary exhibit becomes a surrogate parent to help raise the chicks. "They're moved to a smaller tank with sand and learn to eat; we make sure that they're eating well. Once they get a little bit bigger, they move into an outdoor flight cage where they learn how to fly." After about 35 days, Aimee says, when they're strong enough to survive on their own and satisfy a laundry list of requirements—wariness of humans, a minimum weight of 30 grams, the ability to fly, and the know-how to find food by themselves—they're released back into the wild.
Since the Aquarium's plover rehabilitation program began in 2000, we have successfully released 135 birds and counting. The birds are banded so the Aquarium staff can keep track of them in the wild. "We know that they've been seen reproducing, having eggs and chicks of their own. I feel like we've been really successful at it," Aimee says. "And we are lucky because we're able to help them."
The western snowy plover is a small, white North American plover that wears two black patches on its shoulders. It makes its home on sand, dry mud or salt flats on the edges of ocean beaches, rivers, lakes or ponds in widespread areas around the world. It nests in shallow nooks in the sand—sometimes even using human footprints to keep its eggs.
Since 1993, the U.S. Pacific coast population of western snowy plovers has been listed as threatened under the Endangered Species Act. It's estimated that only about 2,500 western snowy plovers breed along the Pacific Coast from early March to late September. Today, only 28 major nesting areas remain.
Plover nesting areas, which are out in the open in mere divots on sandy beaches, are destroyed as a result of human disturbance, predation by animals and inclement weather. An adult snowy plover scurries away when its nest is approached, and it may be hours before the bird can return. While it's away, its eggs can be crushed, overheat in the sun or become a meal for a watchful predator.
The snowy plover's nesting season occurs during the summer months when people visit beaches the most. Human activities, such as walking, jogging, running pets, horseback riding and vehicle use, are key factors in the ongoing decline in breeding sites and populations. Non-native European beachgrass and urban development also contribute to habitat destruction for the threatened snowy plover population.
A research organization called PRBO Conservation Science has a team of biologists that monitor snowy plovers out in the wild. When they find an injured chick or abandoned eggs, they bring them to the Aquarium's snowy plover rehabilitation program.
As part of the U.S. Fish and Wildlife Service's Snowy Plover Recovery Plan, California State Park employees, biologists and volunteers fence off some vulnerable nesting areas during breeding season to fend off people and predators, and keep an eye on snowy plover nests.
Snowy plover chicks are about the size of a person's thumb when they hatch. Males and females share incubation duties. Females typically desert the chicks shortly after hatching, leaving the early chick-rearing duties to the male. Males then look after the chicks for about a month until they fledge. For the last brood of the season, females generally assist the male to care for the chicks.
A female snowy plover may breed with more than one male, renesting if another male is available and there's enough time remaining in the season.
Males and females defend their nest territories from other plovers by posturing, chasing or fighting. Sometimes a bird may use its bill to grab and pull on its enemy's tail feathers, turning in circles all the while.
Adult plovers don't feed their chicks—instead, they lead them to suitable feeding areas. The chicks leave the nest within hours after hatching to search for food. Western snowy plovers typically forage for small invertebrates in wet or dry beach sand, among kelp washed ashore by the tide and in low foredune vegetation.