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Field & Street

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By Jerry Sullivan

I found my best bird of the spring at Berger Park last Friday morning. Berger Park is at Sheridan and Granville. Most mornings my dog and I take a stroll around it, me looking at the lake, the sky, and the trees, the dog looking at the ground as she sniffs for interesting new smells.

The bird, a male western tanager in full breeding plumage, landed on the rocks that have been dumped along the shore to reduce erosion. The fog that had been socking us in all week still lingered along the lake, so I hadn't brought my binoculars. But I didn't need them.

The tanager landed about 30 feet away. It stood for a few moments, then flew to another rock only 15 feet away. Another short flight took it right past me, and this time it landed even closer.

My bespectacled eyes were all I needed to name the bird at those distances. The breeding plumage of the western tanager features a black tail, black wings decorated with yellow bars, a bright yellow body, and a head of bright cherry red.

This bird was big news for me. Western tanagers nest in the coniferous forests of western mountains. The easternmost nesting location is the Black Hills region of South Dakota. Mlodinow's Chicago Area Birds lists only 6 sightings for this area. Bohlen's Birds of Illinois describes the bird as a "rare vagrant" and lists only 11 reports for the state--"some of which have little or no documentation."

I have seen this species in Texas, Arizona, and Washington, but never in Illinois. My Chicago lakefront list--frozen at 230 species for several years--jumped to 231.

Migration, and especially migration that extends for thousands of miles across oceans and continents, is a very hazardous undertaking. And every time we humans convert a grassland to a cotton field or transform acres of woodland into the roof of a shopping mall, the hazards increase. The winter range of the western tanager extends from central Mexico to Costa Rica. No songbird can make a nonstop flight from Chiapas or Guanacaste to the Black Hills. Like caravans crossing the desert, the birds need oases. Roofs and plowed fields are as devoid of succor for most birds as the shifting sands of the Sahara.

When the sun rises and the night-flying migrants are ready to land--nearly all songbirds migrate at night--they need to eat in a hurry. They are always on the edge. The tremendous energy demands of nonstop flights covering hundreds of miles make starvation an imminent threat.

That threat became quite real for millions of songbirds this spring. The spring migration of large numbers of insect-eating birds is timed to coincide with the opening of the leaves on deciduous trees. The emergence of the leaves stimulates major insect hatches, and the birds recoup their energy losses by feeding on the insects.

As you know, we had a very cold spring this year. It has been so far the second coldest in our history, and it just missed being the coldest. The cold weather suppressed leaf opening, and that led to an extreme scarcity of insects.

The bird migration was late too, but birds can't wait forever. Their drive to fly north is very intense, and their circumstances demand the earliest possible arrival at their nesting areas. They need to carry out their nesting cycle in high summer so they can start back south before the weather begins cooling again. Birds were much scarcer than usual during the first week in May, and most of what we were seeing were mid-April migrants such as white-throated sparrows. Then on the evening of May 9 a warm front moved through. Birds wait for those fronts, using the southerly winds to push them north. On the morning of Friday, May 10, I counted 15 species of migrants on my block.

The following morning I went birding at Swallow Cliff Woods in the Palos preserves. We had a good morning's birding, discovering 65 species. But what was most striking was the number of birds we were seeing on the ground. Cape May warblers, Blackburnian warblers, Northern orioles, and other treetop species were poking for insects among the spring beauties and red trilliums, acting like towhees or thrushes rather than birds of the canopy.

What we were seeing was desperation. These birds had left the treetops because they couldn't find anything to eat up there. The unfamiliar environment at ground level is full of hazards that these species are not really prepared for. You don't need to worry much about coyotes or foxes out at the tips of the tallest branches.

You also don't get too many cars. The message on the Audubon Society's Rare Bird Alert Hotline (847-671-1522) that weekend spoke of large numbers of warblers, vireos, and orioles flattened on roads. In their desperate search for food they were moving out onto pavement, and they were apparently not reacting fast enough to approaching vehicles.

The word was coming in from the rest of the midwest too. Birds were dying in large numbers, killed, directly or indirectly, by starvation. A few degrees difference in the average temperature of the past few months had initiated a catastrophe, a catastrophe visited upon birds that have been taking large doses of disaster already--in the form of habitat loss on their wintering grounds, migration routes, and nesting grounds.

Disasters like this often lead people to complain about the wastefulness of nature. Piles of brightly feathered corpses don't seem to serve any purpose. How could our mother allow such a thing?

But the fact is that nature never wastes anything. If we look at a human enterprise narrowly enough we can make it appear efficient. But in the aggregate, human activity is enormously wasteful. We create mountains of garbage, including very nasty toxics, that we cannot reuse or recycle.

Nature recycles and reuses everything. There is absolutely no waste. A dead warbler feeds a crow, a vulture, a possum, and a host of bacteria.

Of course we do have serious concerns about the continued existence of many of the songbirds pancaked on our highways. And we can feel sympathy for animals that came so far only to end up dead. But what we should mostly think about is how hard and unforgiving life is for wild creatures. And how when we set aside land for nature we need to think of cushions, of how much is needed to protect species even when nature deals them a heavy blow.

I feel some sadness for the western tanager on the rocks. He left those rocks flying east, straight out over the lake. Did he have enough energy to make it to the Michigan side? And if he does get there, where will he be? He won't have the habitat he would need to nest, and even if he did his chances of locating a female are virtually zero. His likely fate is a lonely death. Life is hard. If you can't navigate you are probably out of the gene pool.

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