Naturespeak A naturalist's view of the world

March 31, 2011

Watching the ‘Bergs Go By

Filed under: Uncategorized — wykes @ 9:43 pm

One of the last rites of winter – perhaps the definitive ending – occurs well after the calendar says spring. The winter ice accumulation at the southern end of Lake Huron north of the Blue Water Bridge is called the ice bridge. When this ice pack finally breaks up and flushes down the St. Clair and into the Detroit River it is safe to say that winter is finally over. Traditionally this event begins in March and is completed by the second week of April. Some years it jams up and causes massive flooding while in other years it gently relents. Well, this year’s bridge has finally collapsed (gently, I understand) and the final pieces are now making their journey south to Lake Erie.

Late last week, portions of the lower Detroit mouth were jammed with a vast field of pancake ice (see here a view toward Sturgeon Bar Island). Constant grinding and rotating along the 60 some mile route turned the angular blocks into circular chunks with ridges of ground ice at their edges. This was Huron ice on its way to becoming Lake Erie water. I don’t think there really is a need to explain how the term “pancake ice” came about is there? Now the flow is more spaced out and the last lazy chunks are drifting by at the easy pace of a few miles an hour (see here).

Perhaps the best place to view this current procession of mini-bergs (and say good riddance to winter) is from the boardwalk at Bishop Park in Wyandotte (at a point about mid-way on the Detroit). From the railing the view across to the Canadian isle of Fighting Island the glassy river is dotted with moving white forms. I was joined in this effort by a pair of Ring-billed Gulls (see above). Some of their cohorts were bumming rides on a few of the passing ice platforms (see below) or busily snatching gizzard shad from the waters.

It was a sunny cold day (in fact the kind of day you’d mistake for winter if the ice flows weren’t flowing before you) when I shared the space with these two small gulls a few days ago. The gulls paid me little heed and obviously were used to large two-legged mammals. They briefly eyed my pockets for hand outs, but seeing no offering emerge they went about their daily business. At the time the task at hand was resting.

Ring-bills are one of our most common gulls. Because they are so numerous it is easy to dismiss them as water pigeons or land carp. Up close, however, on a bright day adjacent to their native habitat (as opposed to the parking lot at McDonald’s) they are delicate and subtle. In fact, they seem to go well with the shiny white ice ‘bergs floating nearby. Their small size, yellow feet, and ringed beak (see here) separate them from larger gulls such as the pink-footed Herring Gulls or the similar-sized black-headed Bonapartes.  One detail that escapes all but the closest observer are the fiery red fleshy eye rings (see detail at the beginning) and the colorful mouth linings.

It takes three years for these birds to achieve the adult coloration of this pair. Before that time they have the speckling and dinginess of youth.  As adults, I suspect these snowy white birds will be nesting in the huge colony along the rocks on the east side of Fighting Island. That time will not be for another month or so, but they are already in pairing mode. This point was driven home, not only by the fact that they were “with” each other but by their reaction to another pair that landed on the light post next to them.

The potential rival pair were not welcomed at the ‘berg watch as I was. Both “resident” birds immediately rose their heads up into the air and started a furious bout of cackling. It started with a lowering of the head followed by an upward toss ending with the open beak pointing nearly straight up. Eventually the calls ended in a choking pose as shown in the picture below. Note that the other bird had its head straight down over the railing – looking for  all the world like it was barfing overboard.

This type of behavior is an example of an aggressive call meaning basically “back off Jack.” The un-welcome pair responded in kind, but they got the message. They lifted aloft and sought out another un-claimed piece of railing. Soon this type of thing will happen all the time as the colony birds stake and maintain their spots in the crowded nesting ground just across the river.  The Ring-bills know that their time is coming. It begins with the passage of ice.

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