Salt Glands
Have you ever wondered how waterfowl that spend all or part of the year on the ocean can survive drinking salt water? Seabirds and many shorebirds have a gland above each eye which functions like an extra kidney and draws salt ions out of the bloodstream. Activated by the higher salt levels in the bird’s body, the glands excrete the excess salt through a duct that leads to the bird’s nostrils. From there the salty solution runs down the bird’s beak and back into the sea.
Gulls, terns, petrels, albatrosses, grebes, knots, puffins, loons, penguins, pelicans, sea ducks and geese are some of the birds that possess salt glands. (Photo: Horned Grebe wintering off the coast of Maine)
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Fishing Methods Of Birds With Spear-shaped Bills
How do herons, egrets, bitterns, kingfishers, loons and other fish-eating birds with spear-shaped bills capture their prey? Do they use their bill as a spear and pierce through a fish, or do they grab the fish between their mandibles? You often read about one of these birds “spearing” a fish. However, a majority of these birds, most of the time, do not spear fish, but open and shut their bills fast enough to capture a fish in them — the spear shape of their bill lends itself to the tong-like action it performs. In addition, its shape enhances the movement of the bill through the water as the bird dives (its head or body) into the water to grasp the fish between its upper and lower mandibles.
One exception to this rule is the Anhinga, which does run its bill (which is equipped with backward grooves to prevent slippage) through fish in order to capture them. After spearing a fish, an Anhinga then shakes it vigorously off its bill, tosses it in the air, and catches and swallows it headfirst. (Photo: Great Blue Heron)
Common Loon Chick Meal Delivery
For the first few days of a loon chick’s life, both of its parents are ever-present, catching and delivering small fish, crayfish and invertebrates for their one or two chicks. Their initial buoyancy and their lack of experience prevent the chicks from procuring their own food for the first month or so, although they soon learn how to chase fish. During the first couple of weeks, the parent loon, having caught a crayfish, small fish or other prey, swims right up to its young and offers the chick its next meal. The chick grasps the food while it is still in its parent’s beak. The parent lets go, and the chick attempts to swallow the crayfish (in this case). In the beginning, the chick often drops its meal. The parent then dives down to retrieve it and once again offers the same crayfish to the chick. This sequence of events can happen over and over until the chick finally manages to hold onto and shift the crayfish into a head-first position in order to swallow it. By the third week this beak-to-beak service begins to be replaced by a practice designed to teach the chick how to capture its own meals. The parents start dropping the food they’ve caught for their chick into the water in front of them, forcing the chick to dive and develop the skills necessary for survival. (The pictured loon chick is well into its second week. Close examination reveals that the chick’s “egg tooth,” used to exit the egg, is still present at the tip of its beak. By week #3 it is not evident.)
Common Loons Nesting
Generally speaking, Common Loons return to northern New England from their coastal wintering waters sometime in April or May. Males and females pair up after they arrive at their ponds, and several weeks later they breed and build a new nest or renovate an old one, with the male choosing the actual nest site. Successful nests sites are often reused from year to year, especially if the male returns. Protection from wind, waves and predators is paramount. Because their hind legs are positioned so far back on their body, loons are awkward walkers, at best. Thus, they usually build their nest adjacent to water so that they can easily slip onto and off of it. The nest is constructed during the day by both adults and is made of vegetation that the loons collect close to the nest. A loon often sits on the nest while collecting material, stretching its head down into the water in order to retrieve vegetation which it then places on the nest. Two eggs are laid, usually between mid-May and early June. After being incubated by both parents, the eggs hatch in roughly 28 days. As this photograph indicates (egg just visible below loon’s body), material continues to be added to the nest during incubation.
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