It is only a matter of time before bald eagles breed on Cape Cod.
This is the belief of many bird specialists from the Mass Audubon Society and officials from Massachusetts Division of Fisheries and Wildlife.
Since the 1980s, when the state initiated a restoration project on the Quabbin Reservation in central Massachusetts, the bald eagle population has expanded, branching out to the far reaches of the state. Cape Cod could be next, according to those involved with the project.
“So far, we have not had reports of eagles nesting on the Cape, but we all believe it’s just a matter of time” before the eagles breed on the Cape, said Marion E. Larson, chief of information and education at the Massachusetts Division of Fisheries and Wildlife.
Wayne Petersen, director of the Mass Audubon Massachusetts Important Bird Areas program; Thomas French, assistant director of DFW: and Andrew Vitz, Massachusetts state ornithologist, all agree that Cape Cod is on the verge of having resident eagles.
The last time the bald eagle, America’s official bird emblem, nested in Massachusetts was in 1905. The last breeding pair nested in a tree on Snake Pond in Sandwich before abandoning the state.
At that time, residents feared eagles were a threat to livestock as well as small children, and hunting the bird became commonplace, said Mr. Vitz. Deforestation and the rapid development of the area also threatened the bird.
Today the most common enemy of bald eagles are themselves.
Bald eagles prefer remote, fresh water bodies surrounded by large trees as nesting areas, said Mr. Petersen. They occupy coasts in some parts of the country like Maine, but in Massachusetts, they have not, sticking to large, inland rivers and ponds. As eagles occupy these optimal territories, they fight among each other, either chasing the opposition off or killing them.
The healthy populations of eagles take advantage of these optimal locations, said Mr. Petersen, while the younger eagles are chased farther away, into the less optimal conditions.
Cape Cod is one of those suboptimal locations. “These are not the first areas they would choose, but they are spreading out there,” he said.
In the spring of 2012, Mr. French and the state Division of Wildlife and Fisheries nearly declared a pair of breeders in Mashpee, the first time in over 100 years any bald eagle had nested on Cape Cod.
On Mashpee-Wakeby Pond, the wildlife division spotted a pair of eagles squatting an osprey nest. “We were on the cusp of saying it was a breeder but it was a false alarm.”
The osprey family ended up returning and kicking the pair of eagles out of its nest.
“An eagle will always win when taking on an osprey with a fish. The osprey is terrified of eagles,” said Mr. French. “But in its home, the osprey will chase the eagle away.”
During the recent Christmas bird count in Buzzards Bay, a 24-hour period when birders count as many birds as possible, volunteers counted five bald eagles, the most the counters had ever seen. From 2008 until 2012, the highest number had been two, and before that, zero.
“It’s hard to relate winter numbers to breeding,” said Mr. Vitz. “In the winter, we get an influx of eagles from up north and Canada when ponds freeze.”
But there have been spottings in the summer on the Cape as well. “They may be nesting on the Cape, we just don’t know about it. They are often in tall white pine trees and on conservation land that is closed off to the public,” he said. While the nests are quite large, he added, they can be hard to spot. “It could be that we just haven’t seen any yet.”
There are records of eagles breeding in Plymouth County. There has been some evidence of it on the Cape, Mr. Vitz said, it just has not been documented.
These bird specialists give much of the credit to the potential breeding of eagles on the Cape to the restoration project on the Quabbin Reservoir.
“The restoration of bald eagles to Massachusetts is a great success story,” Ms. Larson said. Mass Wildlife and other conservation minded partners began the restoration effort in 1982 after discovering eagles wintering in the Quabbin Reservoir watershed.
Officials on the project transported young eaglets from wild nests initially from Michigan but primarily from Canada to the reservoir where they were raised in cages. When the birds were old enough to fly, they were let loose.
“This process, called hacking, assures that the young birds would view the area as their home base,” Ms. Larson said. Over time eagles nested on the Quabbin as well as other parts of the state.”
In September of 2011, the Massachusetts Fisheries and Wildlife board voted to down-list the bald eagle from endangered to threatened on the Massachusetts endangered species list.
According to a release from the state fisheries and wildlife: “In 2009, 2010, 2011 and 2012, there were 27, 32, 36 and 39 territorial pairs, respectively, which produced 38, 41, 37 and 33 fledged chicks. This is the 25th year that Bald Eagles have raised young in Massachusetts since their restoration. During these 25 years, at least 486 wild-born chicks are known to have fledged.”