Early Monday morning, Tisbury shellfish constable Danielle Ewart perched precariously on a narrow spit of bog that jutted into Lagoon Pond, and fended off two angry Canada geese with a makeshift plywood shield. While Ms. Ewart held off the furiously honking birds, Tisbury shellfish advisory committee member Ray Lincoln took eggs from their nest and coated each one with vegetable oil. Then he carefully replaced them in the nest — a favored technique for addling goose eggs.
Egg addling prevents eggs from hatching by closing up the small pores that feed the embryo oxygen.
“If you physically destroy the eggs, the goose will lay more, unless it’s at the very end of the breeding cycle,” H. Heussman, biologist at the Massachusetts Division of Fisheries and Wildlife (DFW), told The Times. Mr. Heussman has been studying the Canada goose population in Massachusetts for almost 45 years, and has documented the increasing number of nonmigratory geese in Massachusetts. “Shaking the eggs doesn’t work that well. You have to shake them hard enough to break the yolk, and that’s very difficult, especially in eggs more than three weeks old.”
The DFW generally starts addling efforts on April 15, and the window to act is about a month. This year the schedule was slightly delayed because of the severe winter.
Canada geese are a major factor in the increasing nitrogen levels and the declining health of the estuarine ponds on Martha’s Vineyard, according to several studies.
A 2007 water quality study of Sengekontacket Pond, a prized shellfishing area that has been shut down with increasing regularity, showed that 60 percent of the bacteria in the pond came from waterfowl fecal matter, according to Edgartown shellfish constable Paul Bagnall.
The same study, done by the University of New Hampshire Jackson Estuarine Laboratory in Durham, N.H., revealed that 16 of the 19 bacterial strains found in Farm Pond were directly attributed to geese, one was sourced to cormorants, and two to mixed species, according to Oak Bluffs shellfish constable David Grunden.
“There’s no doubt that geese are a big cause of shellfish closures,” Ms. Ewart told The Times.
When it comes to feces production, geese are stunningly prodigious — the average Canada goose defecates between a half-pound and three pounds a day, according to Mr. Heussmann. Taking an average of one and a half pounds per day per goose, this means a gaggle of 50 geese, a number easily reached on the great ponds and on Ocean Park in Oak Bluffs, leaves behind 525 pounds of feces every week, which is 27,300 pounds a year, or roughly 13.5 tons of dung per year.
Mr. Heussmann said that “Massachusetts geese” is a more accurate label for these birds than Canada geese. In a DFW study done between 2008 and 2012, biologists banded a total of 4,659 geese. Of the 958 geese that were recovered, 72 percent never left the state, and 90 percent were either recovered in Massachusetts or a bordering state.
“Once geese reach maturity at three years, they’ll most likely stay in Massachusetts the rest of their lives,” he said. “The vast majority of these geese have no idea where Canada is.”
On Monday, a Times reporter and photographer accompanied Ms. Ewart and her team on an addling expedition. Successful addling requires locating the nest and shooing the goose and gander away while someone coats the eggs with oil and puts the eggs back in the nest. None of this is as easy as it sounds. Sometimes nest locations are obvious, for example a lone goose sitting at the end of a spit of land.
However, this time of year, that bog can become knee-deep in a flash, and suck the footwear off of an unsuspecting addler. Sometimes the nests are in dense thicket, where the brown and gray feathers blend in remarkably well amid spring vegetation. Around Lagoon Pond, finding nests also required navigating through dense patches of phragmites, a towering, sharp, nitrogen-eating invasive reed.
Ms. Ewart brought along industrial-size trash bags for picking up litter along the way. By the time the trio had trekked a few hundred yards, three bags were full. “We have to organize a cleanup here,” she said. “This is unbelievable. We could do this all day.”
A lone goose sitting at the end of a spit of bog near Ferry Boat Island was a promising sign. The geese confirmed the team was on the right track by honking like a chorus of broken bicycle horns as the trio approached the hidden nest.
Ms. Ewart held up her plywood shield, marked “sea mammal rescue,” and slowly approached the nesting goose. Both goose and gander threatened attack as she methodically stepped toward them. Once the geese retreated, Ms. Ewart held her position while Mr. Lincoln rolled each egg in a bucket of vegetable oil and placed it back in the feather-lined nest.
Addling is definitely best done in pairs. Ganders, the males, can be very aggressive. Ms. Ewart refers to a notoriously aggressive gander on Farm Pond as “Big Boy.”
“The super-aggressive geese you see on YouTube are the exception,” Mr. Heussmann said. “The vast majority of the time they just make a lot of noise.”
“I’d never turn my back on one,” Ms. Ewart said as the trio walked to a second nest.
Over the course of the morning, Ms. Ewart, Mr. Lincoln, shellfish advisory committee member Jackie Willey, and her dog Lady, a lab mix, found five nests. Lady proved to be a valuable member of the team. She easily moved the stubborn birds to a safe distance, and on one occasion, dove into the frigid water and swam after a pair, buying Mr. Lincoln plenty of time to coat the eggs.
Lagoon Pond resident Marilyn Wortman had called in one nest location, and met the crew on the shore and thanked them for their work. “People have to get proactive about this,” Ms. Wortman said. “The geese are ruining the pond, and this time of year, they get very aggressive. My grandchildren play around here, and it concerns me.”
The team addled a total of 25 goose eggs. Ms. Ewart plans to make several more trips by land and by boat, but admits many eggs will certainly be missed.
Still, it was a dent. In two and a half hours, three people and one dog likely spared Lagoon Pond about 37.5 pounds of goose droppings per week. Given that a goose can easily live 10 years — the oldest banded bird Mr. Heussmann has recovered was 22 years old — that is a potential 19,500 pounds, almost 10 tons, of fecal matter potentially removed by one addling expedition.
The addling permit from DFW was issued to the Lagoon Pond Association, which made it possible for the crew to legally traverse private land. Mr. Grunden said while he has been addling around Farm Pond every year since 2008, the scope is diminished because he can only addle on town property or with permission of the property owner.
An all-inclusive addling permit is an option for all great pond riparian societies, as well as for concerned citizens, and there is still time to act. Egg addling permit applications can be downloaded online at the DFW website and faxed in. Mr. Heussman said the turnaround is less than 72 hours, and often is done in the same day. Permits are free.
“Addling has to be done five to seven years in a row to really make a dent,” Mr. Heussman said in an email. “You need several towns to get together and implement a program. Opening up more areas to safe hunting is perhaps the most effective way to reduce populations. And, of course, don’t feed the geese!”
DFW instituted an early goose season that falls in September in an effort to target nonmigratory geese. In 2008, DFW increased the daily bag limit from five to seven geese in an effort to further reduce the number of geese that have made Massachusetts their year-round home.