Seabirds, Part II

Chris continued his discussion of seabirds. Double-crested Cormorants are diving birds, using their huge feet to dive deep into the water. They have a “gular pouch” under their beak that flutters when they are getting rid of heat, and wettable feathers that must be hung out to dry between foraging bouts. Immature birds have a different plumage that signals their age. Dovekies are one of the tiniest auks. The Common Eider: There are only four species in the world. When they molt they become flightless, and they go somewhere safe in the ocean.

One thing that keeps birds more waterproof—especially sea birds—is the preen or uropygial gland, which produces oil that is distributed to feathers while preening. Seabirds and diving ducks have extra-large ones of these. The Herring Gull breeds all across Canada, and they breed inland. Not all gulls are over the sea, so “seagulls” is a misnomer.

Types of gull (note: not all are "seagulls!")

The Great Black-backed Gull: There are many of these in the Isles of Shoals. It takes these largest of the gulls four years to grow to full maturity. Because they need a lot of experience to be successful breeders they must be in full adult plumage (which signals maturity) before they can breed. The Herring and Great Black-backed are pink-legged gulls. Waterbirds have a countercurrent to cool extremities, which minimizes heat loss to the cold environment. Heat flows from arteries to veins along the length of the leg. This conserves body heat.

Laughing Gull: Have a very distinctive, deeper call than the Herring Gull. It’s part of a group of gulls that get a distinctive plumage change with a hood during the breeding season. These are comparatively small.

The Ring-billed Gull is a smaller, not-pink-legged gull that takes 3 years to get adult plumage.

Bonaparte’s Gull is a pelagic bird that will get quite far out in the ocean.
Black-legged Kitiwake: A very pelagic gull, seldom near land. Very delicate. There are several species of Kitiwake. They nest on tiny ledges on vertical cliffs in Norway or Alaska.

Ivory Gulls: These nest in the far north and rarely come south. They spend much time in the dark.

Migration: Nanotechnology is making devices sufficiently tiny to place geolocators on birds, which allows them to gather more information on their migration. They have a light sensor.

These sensors allowed us to gather interesting data on Sooty Sheerwaters: These come from the South in the non-breeding season. These birds go 40,000 miles per year (average of 500 miles/day). They dive up to 70 meters, particularly in the south-little activity near the equator. Another bird, the Bar-tailed Godwit, was tracked, and the data revealed that they traveled from Alaska to New Zealand without resting on the water. They flew, not resting, 7,300 miles non-stop (up to 9 days). (Note: there are birds going over the ocean that aren’t seabirds!)

Conservation and population threats:
• Global warming and climate change
• Large colonies can be especially vulnerable to oil spills
• Fishing nets and long-line hooks
• Chemical contamination of eggs
• Introduced mammalian predators
• Egg and bird collecting

What you can do:
• Join a bird conservation group
• Manomet Bird Observatory
• Puffin Project
• Support USFWS, they manage refuges that protect seabird colonies