What is the 'range' of a bird?

What does “range” mean when talking about a species of bird?

The range of a bird species is the territory in which one would expect to find it living at one time of the year or another. Ranges vary from small areas of less than the size of Rhode Island to nearly the entire world.

Several factors determine a species’ range, chief among them the climate and the kind of soil. Climate and soil affect the kind of vegetation that grows, and vegetation is the source of food, nesting sites and materials, and protection for most birds. Few birds can survive in the desert, where vegetation is spare, but some have adapted to it. Other birds require the sea, or at least lakes or rivers, for their survival.

Various factors also limit range. Oceans are the most obvious; few birds are capable of crossing an ocean under normal conditions. Temperature limits range; few birds can survive an Arctic or Antarctic winter, for instance. High mountains define some range boundaries -- many species are found either east or west of the Rockies.

The Red Knot can be seen in 
Connecticut, but Connecticut is not 
part of the Red Knot's range.

Many birds migrate and their territory includes a “summer” or “breeding” range and a winter range. Often the summer and winter ranges overlap so that a species might live year round in some states or provinces while in other regions, the birds appear only in summer or winter. In the case of such species as the Tundra Swan and the Snow Goose, summer and winter ranges are widely separated.

Although during migration these birds fly over a lot of land and may stop for a bite to eat on the way to and from ranges, the territory in between the winter and summer grounds is not considered part of its range.  For example, the Red Knot has a winter range at the southern tip of South America and a summer range in the northern Arctic. While it can be seen on Connecticut shores in March, Connecticut is just a brief stopover on its long way north and not part of its range.

Free as a bird?

People use the phrase “free as a bird,” but are birds really free?

“Free” is one of those words that mean different things to different people. Americans live in the land of the free, but if they fail to pay their income taxes, they may wind up as jailbirds. Despite being free, we have obligations and even a hobo has the obligations to feed and shelter himself.

Birds, too, have obligations. Foremost is survival. To survive they must feed themselves.

A very free bird?

Since most birds have evolved into feeding on certain kinds of foods, they must live near the sources of that food. Thus, a Sanderling, which lives solely on seashore creatures, is not about to take off from an ocean beach and head for a vacation on the Kansas plains.

Many birds migrate, sometimes thousands of miles, to find food and nesting grounds. Other birds are homebodies, sticking to the same small neighborhoods all over their lives. They are free to choose where to feed and where to nest, but only within restrictions of terrain and location.

Some birds might be said to be “freer” than others. The American Crow and many species of gull are remarkably flexible in the kinds of foods they eat and the territories they inhabit. You will find crows at the edge of the ocean and deep in the desert, in the near tropics and the frozen north, in backyards and thick forests. Some crows migrate, some don’t. And judging from the refrigerator leftovers I’ve seen them eat, they may be the ultimate omnivore.

The sight of a bird in flight feeds the imagination and no doubt inspired someone to concoct the phrase, “free as a bird.”  But birds are mostly bound by both need and instinct to dwell in certain places and follow certain patterns of living.

Humans, who can hop in a car, or board a plane or boat, and travel anywhere in the world, would be the envy of any bird — even the ubiquitous crow — that might have an urge to be free.

Treetop visitors

Spring’s leafless trees are a far cry from Shakespeare's bare ruined choirs of winter. Where late the sweet birds sang is springing to life with song. Those branches are the hotels and summer homes of countless migrants.

The earliest of the tree flowers are blooming. Where there are flowers, there are usually insects. And where “bugs” are, birds are sure to follow. In fact, insects drawn to the early-flowering trees are important food for warblers, tanagers and other small migrants heading north in the weeks to come. Some will stop here to nest for the summer while many others eat and run, heading farther north.

For bird watchers the leafless limbs of early spring are a blessing. The scores of colorful arrivals are much easier to spot without lots of green blocking the view.

So instead of watching spring arrive on the thermometer, dust off the binoculars and point them to the passing parade of treetop visitors.

Supply and demand

Day and night, the sky is alive with life. Migration has begun, and literally millions birds are silently streaming northward in search of nesting grounds.

Only a fraction of these travelers are seen locally, however. They pass by high overhead, often in the middle of the night. Most don’t stop and those that do may pay only brief visits or spend the time sleeping. Sometimes, though, they make forced landings. Countless Fox Sparrows were grounded by the recent nor’easter, showing up in flocks at feeders where they had never been seen before, and generating a flurry of excitement in the bird-watching world – even inspiring some newspaper stories.

All these northbound birds are heading for territory that is barren in winter, but lush with food, both insects and vegetation, in spring and summer. What’s more, the northlands offer virtually unlimited nesting sites – unlike the crowded winter grounds of the South or the tropics.

Thus, migration is nature’s efficient way of handling life’s supply and demand.

The survivalists

The season of migration is well underway as millions of birds flee the coming cold.

Their journeys often amaze us with their length and navigational expertise. The Arctic Tern flies 11,000 miles from northern Canada to Antarctica each fall. The hummingbird, weighing but a fraction of an ounce, may traverse a thousand miles of the Gulf of Mexico to reach winter grounds. Many songbirds fly hundreds of miles each night, guided only by stars or some invisible magnetic field.

Amazing all. But what of the birds that choose to stay? Are they just lazy? Hardly.

While their migrating brethren are enjoying temperate shores and tropical forests, our year-round birds face cold and snow. They must survive winter’s winds and frigid temperatures. They must find sustenance when a foot or more of snow covers the ground. Many must spend months in preparation, storing food for winter use – and later remembering the hundreds of caches they made.

Whether they are winging their way to warmth, or just crouching against the cold, birds are astounding survivalists.

Hitchhiking hummers

Nature inspires much lore. Dragonflies sew up your mouth. Toads give you warts. Bats land in your hair.

But a magazine, not children or backwoods naturalists, dreamed up a tale about hummingbirds, those hovering micro-birds that just now getting ready to return to Central America. In the 1880s, a writer proposed that Ruby-throated Hummingbirds, which weigh only an eighth of an ounce, couldn't possibly fly non-stop across the Caribbean on their way to and from North America. Without any evidence in hand, he theorized they hitchhiked on the backs of such larger birds as Canada Geese.

Today, we know this is not true, yet the speculation has been told and retold till many consider it fact. But as is often the case in nature, fact is more amazing than fiction. Rather than hitchhike, this miniature creature, wings whizzing at 80 beats per second, zips non-stop across 1,000 miles of open sea at up to 40 miles per hour, twice a year.

Even more amazing is its metabolism. If you weighed 170 pounds and lived like a hummingbird, you'd burn 150,000 calories a day and produce 100 pounds of sweat. And if you ran out of water, your skin temperature would surpass the melting point of lead and you'd probably catch fire.

Free as a bird?

People speak of being “free as a bird.” But how free is a bird?

“Free” is one of those words that mean different things to different people. Americans live in the land of the free, but if they fail to pay their income taxes, they may wind up as jailbirds. Despite being free, we have obligations. Even a hobo has the obligations to feed and shelter himself.

Birds, too, have obligations. Foremost is survival. To survive they must feed themselves. Since most birds have evolved into feeding on certain kinds of foods, they must live near the sources of that food. Thus, a Sanderling, which lives solely on seashore creatures, is not about to take off from an ocean beach and head for a vacation on the Kansas plains.

Many birds migrate, sometimes thousands of miles, to find food and nesting grounds. Other birds are homebodies, sticking to the same small neighborhoods all of their lives. They are free to choose where to feed and where to nest, but only within restrictions of terrain and location.

Some birds might be said to be “freer” than others. The American Crow and many species of gull are remarkably flexible in the kinds of foods they eat and the territories they inhabit. You will find crows at the edge of the ocean and deep in the desert, in the near tropics and the frozen north, in backyards and thick forests. Some crows migrate, some don’t. And judging from the refrigerator leftovers I’ve seen them eat, they may be the ultimate omnivore.

The sight of a bird in flight feeds the imagination and no doubt inspired someone to concoct the phrase, “free as a bird.” But birds are mostly bound by both need and instinct to dwell in certain places and follow certain patterns of living. Humans, who can hop in a car, or board a plane or boat, and travel anywhere in the world, would be the envy of any bird – even the ubiquitous crow – that might have an urge to be free.