Foam Lake Birding No. 56

No. 56
In keeping with the theme of marsh birds during this rainy weather, I decided to cover another very common group of marsh/lake birds, the terns. Terns are related to the gulls and are similar to them in many ways, but also differ in many ways. (I guess that is why they are terns and not gulls). Both are aquatic and can swim; both tend to be white with black and grey trim; both are very noisy; in both groups, males and females are the same. They differ in that: gulls are regular swimmers while terns seldom swim; gulls stray from water and look for food on fields, parks and garbage dumps while terns do not; gulls eat just about anything while terns almost always catch their prey.
Nothing written above is very useful in identifying terns in the field, however, there are field marks that distinguish the two groups. First, most terns are white headed with a black cap; gulls do not sport black caps. Second, a tern’s bill is usually red and is always slender and sharp; a gull’s beak is usually yellow and always blunted at the tip. Third, terns are usually smaller and more delicate than gulls. Fourth, terns have longer tails that are usually forked to some degree. Fifth, terns have longer and more pointed wings. Sixth, terns are much more buoyant and graceful fliers. Overall, a tern looks like a gull that has many of the physical characteristics of a swallow. For non birders, a tern is like a tricked out sports car while a gull is more like a minivan or SUV.
Locally, four species of terns can be expected: two are common; one is uncommon; one is rare. This week’s featured bird, the Black Tern, is probably the most common tern around here with just about every permanent slough supporting at least one pair. While, its overall characteristics are definitely that of a tern, its colour scheme most certainly is not. Rather than white, its body is all black with dark grey wings, back and tail. The bill is black and not red like the other terns. Most terns hang around larger lakes and ocean with clean shore lines, but the Black Tern lives in reedy sloughs. It nests on a floating platform on the water while the other terns nest on sandy and rocky shores and cliffs. If it were not for Black Terns, our prairie sloughs would be devoid of terns, altogether.
Black Terns are very easy to find and identify even by beginning birders. To see these terns a birder should head out to the nearest marshy slough and wait for the birds to fly over head and start scolding. They do not like intruders. To get a really good look at a Black Tern, one needs to find a slough with fence posts that are still standing in the water. Terns love to perch on these, thus permitting an observer to get a really good look.
This week I have provided two pictures of a Black Tern – on flying and one sitting on a raft of reeds (perhaps a nest?). Because there were no standing fence posts, I could not get a nice profile shot. This week’s pictures were taken at the same location and at the same time as the pictures of last week’s bird, the Ruddy Duck.