December's dramatic sightings

Posted: Friday, December 24, 2010

Geese and ducks often fly from the wetlands to Auke Lake, as long as some open water remains there. These flights are especially noticeable during the hunting season, when the wetlands are dangerous for waterfowl. It’s classified as a game refuge, yet during the hunting season, the wetlands are not much of a “refuge.” Instead, they are a perilous place for those targeted by shooters. When hunters are active on the wetlands, Auke Lake offers a comparatively safe haven during these days, and the waterfowl return to the wetlands at night, to feed in the dark as best they can.

But Auke Lake, however, is not totally safe. On a recent walk near the lake on the broad, smooth trail completed a couple of years ago, we saw that safety had come to an end for one goose. We missed the actual strike, but there on the ice was an eagle, happily (one supposes) tossing feathers aside and nipping small red chunks from its still-living prey. The goose flapped its wings occasionally, but to no avail, and before long, it was over for the goose.

The eagle continued its lunch, surprisingly unmolested by ravens or magpies. Another eagle swooped in but was told off, in no uncertain terms, by the owner of the carcass. A second interloper was chased over the ice for some distance before giving up. Lunch, for the eagle, was finished in peace.

Other sightings were less dramatic. Up along Fish Creek, as we were sampling aquatic insects, a friend watched a winter wren that was not doing its normal flitting through brush piles and stumps. Instead, this one was out in the open at the edge of the creek. It took one tiny item from the water surface and then probed the gravels for a few other morsels. More like a dipper than a typical wren.

A northern hawk owl has been seen in the Brotherhood Bridge area. Hawk owls are visual hunters, typically foraging during the day. A bird of boreal forests, it also hunts along forest edges. It is customarily a sit-and-wait hunter, perching quietly on a branch or snag while scanning the area around the perch, then changing to a new perch. They can also hover for short periods, and sometimes, like the forest hawks, they wing rapidly among the trees to startle potential prey into revealing themselves. Hawk owls feed primarily on small mammals and birds, but they can also take prey as large as ducks and grouse up to two or three times their own body size. Although they can spot prey from hundreds of yards away, the usual strike distance is less than 50 yards. They are reported to have better hunting success when snow does not cover the ground.

Hawk owls, like other owls, catch prey with their feet, and often carry them to a plucking post. There the owl rips off feathers, tails, feet, or other unwanted but easily removed parts, and swallows the prey whole. Later, the undigestible bits are regurgitated in a pellet. Hawk owls, averaging about eleven ounces (but females are bigger than males) and perhaps fourteen or fifteen inches long (including a long tail), can swallow two whole mice in quick
succession.

Northern hawk owls nest in Southeast, but rarely. They are more common in the Interior. However, if prey becomes scarce there, they move south some distance, until they find better hunting. Hawk owls can store prey in snow, tree holes, stumps, or thick branches; one observer noted storage of twenty prey items in three hours. Prey is also stockpiled at the edge of nests.

They commonly nest in tree cavities or sometimes on snags, and there can be fierce competition with squirrels, kestrels, or certain ducks that also use such nesting sites. Male hawk owls show several potential nest holes to their mates, and the female then chooses one of them. She lays an unusually large clutch of eggs (for an owl), averaging seven eggs per nest but sometimes as many as thirteen. Incubation lasts just over four weeks and begins well before the last egg is laid, so the chicks hatch asynchronously and there are chicks of all sizes in the nest. They are fed frequently and grow very fast. They are reported to leave the nest when they are about three weeks old, long before they are able to fly, and the parents feed them on the ground or wherever they find them. Presumably, the youngest and smallest chicks die of neglect and starvation if food is scarce, as is typical of many other birds.

• Mary F. Willson is a retired professor of ecology.



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