For shorebirds on Georgia beaches, nesting and rearing chicks requires surviving a gauntlet of threats. Some of the deadliest come with fur: raccoons and coyotes.
But using National Fish and Wildlife Foundation funding, scientists at the Georgia Department of Natural Resources have documented ways to limit the impact these predators have on two shorebird species of concern, Wilson’s plover and American oystercatcher. One welcomed result has been more productive nesting seasons for both, according to project leader Tim Keyes of DNR.
“In both cases, we moved the needle on one of the three biggest threats for shorebirds,” Keyes said.
Those top three threats are tides washing over nests, human disturbance and predation by mammals. The Atlantic Flyway Shorebird Initiative, an international effort to stem shorebird declines from the Arctic to Argentina, has been working on these and other issues for years. The National Fish and Wildlife Foundation has provided key support, including in Georgia. Known to many as NFWF, the foundation was chartered by Congress to connect federal, corporate and other partners for conservation.
Keyes said DNR’s current grant has helped survey for banded oystercatchers and map horseshoe crab spawning area (the eggs are a critical food for federally listed red knots). Yet another highlight has been research by staff and a University of Georgia graduate student on non-lethal methods to curb predation of Wilson’s plovers nesting on Little St. Simons Island and oystercatchers on Cumberland Island.
For the past two years, UGA’s Lauren Gingerella has put screen cages over about 50 of the 200 Wilson’s plover nests she has monitored on private Little St. Simons. The cages let birds in but kept raccoons out.
“Both years, nests with the enclosures hatched and fledged significantly more chicks,” Keyes said.
While cages increasing nest success seems a given, Keyes, a biologist with DNR’s Wildlife Conservation Section, explained that other questions were involved, such as if the screening would cause parents to abandon a nest or actually draw predators to eggs and chicks usually hidden by natural camouflage.
The work on Cumberland Island National Seashore took a different tact: Six oystercatcher nests were circled with solar-powered electric fencing to ward off coyotes, a leading predator not found on Little St. Simons, and raccoons. DNR and National Park Service staff monitored the nests.
Although the sample size was small, five of the six nests fledged chicks, seven total. For comparison, only two chicks survived Cumberland’s coyotes and raccoons in 2017, and none some years before. In 2018, however, the island accounted for more than one-tenth of Georgia’s record high of 61 oystercatcher chicks.
Keyes emphasized that these approaches aren’t for every site, and coyotes and raccoons often adapt and determine new ways to prey on shorebirds and nests. “There is no single silver bullet for predators.”
But with American oystercatchers, it’s clear that “in the right situation we can use non-lethal predator management to significantly increase productivity,” he said. For Wilson’s plovers, the insight from the use of exclosures adds another tool for conserving these birds and their offspring from predators.