The Egg Hunt: Update on Ben West’s Guillemot Study

Guillemot nesting habitat on East Beach

Guillemot nesting habitat on East Beach

Today I accompanied Ben on his hunt for Black Guillemot burrows on the rocky cliffs and coves of East Beach. His project, like many others, has changed significantly from my first excursion into the field with him. Initially, Ben tried to find burrows by observing the Guillemots from inside of his handmade bird blind, but the birds remained stubbornly on the water and refused to lead him to their nests. Ben realized that finding burrows on Kent Island is enough of a challenge for the summer, and decided to limit his research to Kent Island. He adjusted his burrow surveying strategy to investigating likely spots around the island on foot.

Looking for the burrows with Ben was like a giant Easter egg hunt, with the added excitement of furthering scientific research with our discoveries. While grubbing for Guillemot eggs is similar in theory to grubbing for Petrels, shoving my hand between boulders was a very different experience from feeling my way through earthen tunnels. Guillemots prefer dry, protected burrows close to shore, and tend to build them in dark cracks nestled between rocks. We had to contort ourselves into strange positions to reach our arms into potential burrows, which were on the beach, in sheltered coves, and on top of bluffs. Gulls nests were everywhere underfoot, some filled with eggs, others with spotted fluff balls that I realized were newly hatched chicks. What seemed like hundreds of gulls screamed and flew low overhead as we neared their nests, fiercely protecting their young.

Ben West marking a Guillemot burrow on East Beach in his herring gull protection hat

After an hour of fruitless clambering and braving the aggressive gulls, I saw a light gray gleam deep between two boulders. Ben identified the speckled egg, which was slightly larger than a chicken egg, as a Guillemot’s, and we were on our way to increasing his sample size. He marked the burrow with an orange flag and recorded its GPS coordinates so that he can locate it when he checks the burrows again for further eggs and Guillemot chicks. Ben’s survey of the Guillemot burrows on the Island is the first since former BSS director Bob Mauck’s survey eight years ago, which found a whopping 92 burrows. The Guillemot population has nearly doubled since a 1947 survey that found 50 burrows (Winn, 1947). The recent proliferation of Guillemots may be due to declines in predators, namely the herring gulls that have decreased in number because of the decline of the herring industry in the Bay of Fundy. As of this afternoon’s search, Ben has found ten burrows, with a goal of thirty for his study.

Ben constructed a group of artificial burrows out of rock-covered PVC pipes that imitate their dark, sheltered natural habitats. “Basically, I’m operating under two hypotheses, that nest sites are limited and that they vary in quality,” Ben explained. If the birds nest in his artificial burrows, it may indicate that their population is constrained by the number of available natural nesting sites. He will compare how well the birds do in different nesting sites, such as cracks between boulders, driftwood piles, and his artificial burrows. To evaluate their success, he will measure the average number of chicks that hatch in each burrow, because according to Preston, the maximum Guillemot mortality occurs when they are still in the egg.

Even if there are enough natural nesting sites that the Guillemots ignore his burrows, Ben’s survey will provide the BSS with valuable data for future studies of the birds. I look forward to helping him continue the search, especially for baby Guillemots, whichI have heard rival the herring gull chicks for cuteness.

Newly-hatched Herring gull chick

Newly-hatched Herring gull chick

Source:

Winn, H.E. 1947. The Black Guillemots of Kent Island. Bulletin of the Massachusetts Audubon Society 31. (BSS Contribution no. 19)

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