Have you noticed all the robins lately? Seeing that first robin is often thought to be a welcome sign of spring. This year massed flocks of robins have been back for weeks of anything but springlike weather. What could possibly have triggered such a migration north into some of the harshest winter temperatures we’ve experienced in many years? It’s clear that spring migrations are triggered by more than warmer temperatures and longer day lengths. Food availability and harsh weather in the wintering area can also induce migrational movements. There has been a great deal of harsh winter weather down south this year. The South has had below-freezing cold, snow storms and more ice events that we have. That could have made feeding difficult where wintering robins would typically be able to feed on unfrozen ground. Couple that with the fact that we had a bumper apple crop last year. Those crab apples and even regular apples were up in trees where birds could get at them, even after ice storms. Maybe there was better access to food here than there was down south.
We have also had scattered reports of bluebirds in recent weeks. I saw a couple myself several weeks ago while looking for nesting eagles. It might be a good idea to get any bluebird houses near you closed up and ready. Early-migrating bluebirds use nest boxes as night roosts, especially during late winter storms that could still hit us for at least a month. Some of our winter residents will be starting their return to more northern breeding areas in the weeks ahead. Eagles (other than local resident pairs) will be moving north again at about the same time as the geese do. The geese are just waiting for enough thawing to open up some water farther north to begin their spring migration. Dark-eyed juncoes and true sparrows will be moving back north in the next few weeks, too. It’s a good time to keep your eyes on your feeders as these birds begin to move. My feeder has hosted a young Harris sparrow, a white-throated sparrow and some tree sparrows lately. A friend has had a fox sparrow. Several other sparrow species could be mixed in with the usual run of English sparrows that mob our feeders.
Most bird books of the past had beautiful paintings or photographs of birds in their normal breeding plumage as they’d appear in spring or summer. A few books might have added some pictures of normal fall plumage if it was different. I emphasize the word “normal” here because some species have a fairly high likelihood of showing up in colors and patterns that are quite different than those the bird books show. A few of the more recent bird books show at least some these alternate color, “morphs,” as they’re known.
Red-tailed hawks that we see so often soaring in circles or perched on interstate highway signs are really quite variable in their coloration. The majority of red tails will be in the “normal” range, with only slight variations from lighter to darker. The extreme ends of the color range extend from nearly white with a very pale back and a slightly pink tail, to nearly black all over. These color variations can occur between siblings in the same nest. The lightest and darkest red-tails are more commonly seen farther west, but occur at some level throughout their range. The nearly white Krider’s red-tail and the nearly black Harlans hawk are all part of the large and diverse red-tail clan, though. Some of the other large soaring hawks, known as buteos, also display similar ranges.
Mammals, too, can trip us up if when they appear in mutant color phases that are far from what we might normally expect to see. I’ve been enjoying an unusually colored squirrel in my yard this late winter. It has a lovely nearly black sable color all over its chin, belly, and feet where a normal squirrel would show orange. Its back is somewhat darker, too. I have seen similar color variations in squirrels elsewhere in Nevada, so it’s clear that there is a genetic tendency for this trait in our local population. Members of the dog family; particularly foxes, can occasionally show up with most unusual color patterns. This should come as no surprise since that vast range of colors and patterns in domestic dogs were all buried in the genetic makeup of their common ancestor, the gray wolf. The conservation center has skins from two almost entirely black wild foxes, a color phase known as a silver fox due to the whitish tips on some of the hair on the back. Fox breeders can select for that color and others, but they do occur with some regularity in wild populations. Rarely, deer show up as partially or totally white, even if they’re not true albinos. A few are seen around Iowa each year and are illegal for hunters to take. The conservation board has the skin of a partially white deer, known as a piebald coloration, that was killed by a car some years ago north of Ames.
Keep your eyes open and enjoy the variety that Mother Nature has to offer us.
(Steve Lekwa is director of Story County Conservation. He lives in Nevada.)