Archive for year: 2013

Author: Sally White

Illustrations: Jan Ratcliffe

Date: May 2013

Sparrows don’t quite do it for me: I look at them and I clearly see birds, normal birds, hopping on the ground looking for seed or flying around. But distelfinks are different. Distelfink, literally “thistle finch,” is a handy word still used by the Pennsylvania Dutch for a group of birds that reminded them of the colorful finches of their homeland. It’s both memorable and descriptive, as distelfinks of all species adore thistles—in season, of course. Perhaps you’ve encountered flocks of pine siskins and lesser goldfinches raiding roadside thistle patches in fall, and fluttering wildly away as each car passes. For me, it’s less trouble to say “distelfink” than to list all our yellow finches—pine siskins and American goldfinches and lesser goldfinches—and our pinkish-red finches—purple, house, and Cassin’s finches. Other birds never act like dinosaurs. Distelfinks do, at least at my house.

Scientists who study fossils have, of late, been trying to tell us birds are actually dinosaurs: watching distelfinks makes me a believer. Ounce for ounce, they must be among the most aggressive dinosaurs left alive. This is made apparent by their habit of congregating in mixed flocks for fall and winter feeding. After all, most of us get a little irritable in crowds. Pine siskins are the worst. As they fight for space at the thistle feeder in our yard, they hiss and spit at each other, flashing the yellow under their wings and adopting threatening postures. Sometimes I think firebreathing dragons are the true missing link between birds and other dinosaurs, the extinct ones.

All this aggression is presumably brought about by the survival value of simply getting enough food. Small birds come together in numbers because of the advantages flocking offers: better protection and a warning system for predators. Flocking also means more eyes on the lookout for good food sources, but you still have to get your share while dozens of your fellows try to get theirs. Picture the noon crowd at your local food court.

Fortunately, we have a lot of thistle patches around. Therein arises one of those conundrums of conservation. Plant enthusiasts are trying to eliminate exotic thistles; bird enthusiasts enjoy thistle patches for the many birds they support. Although we have a variety of native thistles, most don’t thrive quite the way foreign invaders like musk and Canada thistle do. Have we improved habitat for distelfinks by allowing alien thistles to spread unchecked these last hundred years? Yes and no. Native birds do have alternatives: pine siskins are aptly named because they pick at pine cones as successfully as at thistles; American goldfinches are equally happy eating sunflower or dandelion seeds. Although their numbers may have increased with new food supplies, I don’t think removing exotic thistles will drive distelfinks toward extinction.

Flocking, or perhaps we’d better call it herding, probably also provided similar advantages to some dinosaur species. Communal dinosaur nesting grounds in Montana remind us of today’s seabird colonies, substituting groups of 25-foot-long duckbills who return to the same place year after year to nest together and care for their young. A herd of these Maiasaura migrating from nesting areas to feeding grounds might foreshadow the long migrations our flying dinosaurs make today.

I imagine the pine siskins as coelurosaurs: scrappy, ostrich-like dinosaurs who may have hunted in groups. Solitary eagles are more reminiscent of lone hunters like Tyrannosaurus rex. A small peregrine falcon may recall Velociraptor; both have a strike that is quick and deadly.

Paleontologists have given us a lot to think about with this bird connection. Just think—now you can study dinosaurs in your own backyard! Much of our understanding of the past must come from our knowledge of the present, because Nature still works much as it did during the Cretaceous Period. Even scientists use their imagination, and often reason from analogy as well as from hard facts. As the famous geologist James Hutton once put it: The present is the key to the past. So if you want to see dinosaurs at home, and speculate on Earth’s older inhabitants, you’re in good company. I should warn you, however, that the bird specialists have not yet fully accepted this new, closer link between dinosaurs and birds.

Because birds are ubiquitous and seem to be a harmless background presence, we don’t consciously notice how thoroughly they’ve occupied “our” world. When you think about it, they’re everywhere. In and amongst our supposedly dominant culture, birds as a group continue to thrive and still live a variety of lifestyles. They are, however, showing the effects of our presence and the pressures we put on them; too many are disappearing. Those earlier dinosaurs, in their heyday, must have similarly dominated their environment, and eventually succumbed, perhaps due to some similar pressure. May the distelfinks last as long.

Copyright © 2013 Sally L. White

Author: Sally White

Illustrations: Jan Ratcliffe

Date: February 2013

Our world is surprisingly full of animals, even in our heavily developed areas. How does nature ensure that fullness? By paying a large price: excess. This annual tax often comes due in winter. Every student of nature stumbles upon and must come to terms with the necessity for such excess. Charles Darwin once remarked upon the “clumsy, wasteful, blundering, low and horribly cruel works of nature.” Henry David Thoreau sounded a somewhat more optimistic note: “I love to see that Nature is so rife with life that myriads can be afforded to be sacrificed and suffered to prey upon one another.” Whatever we may think of this system, it works.

In the plant world, we find it useful to describe life cycles by their duration. For example, we understand some plants to be annuals that go from seed to seed in a single season, investing all their energy in the next generation. Others are perennials that take several seasons (or decades) to grow, reproduce, and die. The concept is equally useful when applied to animals. Some animals, especially among the insects, could be considered annuals, going from egg to egg in a single season or year. Even those who could live for years用otential perennials熔ften don’t. Winter is one of the reasons for shorter lifespans.

Many insects invest any hopes they have for the future in an egg or pupa that is dormant during the cold months; most butterflies use this approach. Others, for example hornets, go from the abundance of a large “city”葉he paper nest with its thousands of inhabitants葉o a few adult queens, stocked with sperm for the following spring. At least one must make it through winter to begin again. On the average, one does. Ladybird beetles also go through winter as adults, coming together by the thousands each fall to hide in crevices and other sheltered places on mountaintops. For animals large and small, winter success is often a matter of survival of the fattest. Stocking up enough reserve energy to get through the winter is especially important to those who will not look for food again until spring: bears, snakes and lizards, frogs and toads, hibernating ground squirrels, and many more. They sleep, gambling that the fat they’ve stored will last longer than the winter ahead.

Others remain active, using hidden food caches as pine squirrels and scrub jays do, or searching for food all winter as deer and elk do. Stocking up is still important, though. The more energy they’ve been able to store internally during summer’s abundance, the better their chances of finding enough external food sources to get by. Among birds, many escape the rigors of winter by migrating, but there is no escaping the annual tax, and no way the world can hold all the young produced each year. In 1991, volunteers for Hawkwatch International counted a thousand Sharp-shinned hawks migrating over one mountain ridge in Utah; almost 50% were immature birds making their first trip south. Only about 30% of those young birds will live to make the return trip. By our standards, this reflects an oppressive tax indeed; by nature’s standards, it is a necessary one.

Our smallest winter-resident bird, the chickadee, lives all winter on a nutritional and energetic edge. In ten years, Aldo Leopold banded 97 chickadees on his Sand County farm. Only one survived five winters; 67 didn’t make it past their first. But survival isn’t just a lottery; much can depend on the decisions the animals themselves make. Read the chapter on chickadees that ends his Sand County Almanac擁t’s one of his best.

“It seems likely that weather is the only killer so devoid of both humor and dimension as to kill a chickadee….To the chickadee, winter wind is the boundary of the habitable world….Books on nature seldom mention wind; they are written behind stoves.” 輸ldo Leopold

It’s no wonder, then, that animals do whatever they can to reduce the demands winter places on them, to increase their chances of being here come spring. Deer invade your yard to eat fall apples or early spring tulips; mice and squirrels, along with wasps and spiders, invade your house in search of warm spots where their limited stored energy will not be drained by cold. It’s going to be a tough time to be outdoors, and somehow the animals know it. That wasp wedged under the bark in your woodpile may be the queen of a new city; the spider in the corner of your porch could found a new dynasty; the mouse in your basement is the matriarch of next summer’s owl food. All are just doing the job nature assigned them at a time when she’s not about to make that job easy.

Copyright © 2013 Sally L. White