Terns Thrive, Plovers Numbers Fall On Monomoy Refuge

By: Tim Wood

Topics: Monomoy National Wildlife Refuge

Terns on the Monomoy National Wildlife Refuge last summer. South Monomoy Island hosts the largest common tern colony on the eastern seaboard, with 11,723 nesting pairs this past season. KAT SZMIT PHOTO

CHATHAM – While terns did well on the Monomoy National Wildlife Refuge last summer – the refuge remains the largest common tern colony on the eastern seaboard – the number and nesting success of federally-endangered piping plovers fell below expectations.

A total of 48.5 pairs of the small, sand-colored plovers nested on the refuge, a decrease from 52 pairs in 2016. Most (46 pairs) nested on South Monomoy, one was on North Monomoy and one on Minimoy Island. U.S. Fish and Wildlife staff keeping watch over the flock from a field camp on South Monomoy documented 34 fledged plover chicks, a productivity rate of .70, down from 1.52 the previous year. The five-year average productivity for plover chicks is .94, short of the 1.5 fledged chicks per pair goal, according to a report on last season's bird activity on the island.

Increased predation and two king tides in the spring, which overwashed the beach and destroyed eight nests, are the main reasons for the low productivity.

“We lost a lot of nests due to that,” Refuge Biologist Kate Iaquinto said of the weather events. Plovers like to nest on wide, open beaches, and while the refuge's beaches are quite wide, the tides were higher than usual.

Plover nesting tends to be “hit or miss,” she said. “There's not a whole lot more we can do for plovers besides additional predator management.” Coyotes and grackles – which have recently started breeding on the refuge – are the main plover predators. Four coyotes were removed by personnel from the U.S. Department of Agriculture's Animal and Plant Health Inspection Service, who spent 40 days on the island in the spring. They also trapped grackles, Iaquinto said. The same predator controls will be in place this season, since additional predator management is too expensive, she added.

“One coyote can do a whole lot of damage if it gets into the tern colony,” she said.

At other sites in Chatham, piping plovers fared a bit better, according to a summary of the 2017 Massachusetts Piping Plover Census released by the Massachusetts Division of Marine Fisheries National Heritage and Endangers Species Program. On North Beach, 16 pairs produced 31 chicks. On North Beach Island, there were 20 pairs with 14 chicks. South Beach hosted 18 nesting pairs, with 12 chicks fledged. Forest Beach had two nesting pairs with three chicks fledged, and on Harding's Beach three pairs produced four chicks. Two pairs on Ridgevale Beach resulted in three chicks.

In Orleans, Nauset Spit had nine nesting pairs producing 16 fledged chicks, while Nauset Beach South produced 27 fledged chicks from a total of eight nesting pairs.

Statewide, 650 pairs of piping plovers nested at 147 sites, with 688 chicks reported fledged, an overall productivity rate of 1.07 fledglings per pair.

On South Monomoy a total of 11,723 pairs of common terns nested, a 12 percent increase from the previous year. There's been a steady increase in common terns since 2009, when 2,300 pairs nested. Iaquinto attributed the success to habitat management, including controlled burns that basically increase prime nesting area at the northern tip of South Monomoy. A few years ago terns were nesting in only about half of the 35 acres, and now they're using about three-quarters of the habitat.

“They've expanded their nesting down south, and they're nesting a lot less closer together,” which helps maintain the health of the colony, she said. Because of its permanently protected status, terns from other areas where habitat is disappearing flock to Monomoy. “If we didn't (protect Monomoy), they wouldn't have a whole lot of other places to go,” Iaquinto said.
Eighteen pairs of federally-endangered roseate terns nesting on South Monomoy last season, an increase of four pairs over the previous year. Productivity was lower than average. Roseate terns have shifted south in recent years due to habitat management and nesting boxes deployed by refuge staff.

Laughing gulls, which nest within the tern colony, are becoming a concern. There were 2,714 pairs on South Monomoy, and that's after 2,000 nests were destroyed. Laughing gulls compete with terns for territory, steal food and kill tern chicks. Officials hope that the number of laughing gulls will go down if nests are destroyed for a few nesting seasons. Iaquinto said Monomoy can support about 1,000 pairs, which are tolerated because there aren't many laughing gull nesting sites in the state.

“Pretty much all of the laughing gulls in Massachusetts are nesting on Monomoy,” she said. This is about the northern end of the species' range; over time, Monomoy may see more, because of lack of habitat and other factors.

There were 773 least tern nests, down from 842 in 2016. Eighteen American oystercatchers nested on the refuge, with poor productivity. There were also 185 black-crowned night heron nests, 100 snowy egret nests, 25 great egret nests and three glossy ibis nests. These wading birds nest primarily on North Monomoy Island, which has been eroding due to the 2013 break in South Beach. If the saltmarsh habitat continues to degrade, wading bird habitat will be reduced, the report states.

Also last season, the refuge collaborate with the Fish and Wildlife's Raleigh Field Office, the North Carolina Botanical Garden and the Massachusetts Department of Fish and Wildlife to plant federally threatened seabeach amaranth on South Monomoy. Some 2,000 seeds were plants in 14 plots along the eastern side of the island, with more than half germinating and hundreds of plants fruiting, according to the report. This was the final step in a federal project involving six wildlife refuges in four states. Staff will search the area this season to determine if a local population was established.

Refuge Manager Matt Hillman said no new initiatives are planned for the coming season. There will be the usual seasonal personnel to staff the field camp and a program of refuge tours launched last season will continue. The refuge is also reaching out into the community with booths at local farmers markets, which he expects to continue.