Our Window on Nature

Why don’t perching birds fall out of trees when they take a nap? Or off of phone lines when the wind starts to whip the bird up and down? Birds may seem to have a much better sense of balance than the rest of us, but the real answer is in the structure of their legs and feet.

Watch one of your local birds the next time you see it about to land on a branch. The first thing you’ll notice is that the bird stretches out its legs just before touching down. And what may happen too fast to observe is the bending of the leg after landing. These two actions are the secret to what at first glance seems like a remarkable balancing act.

There are flexor tendons that run down the bird’s legs, and when the leg is straight, the tendon is more or less relaxed. But when the leg is bent upon landing, it stretches these tendons, which in turn clench the bird’s toes, causing them to lock around the branch or wire.

And falling asleep doesn’t change the grip, since the weight of the bird keeps the leg in the locked position. When the bird is ready to leave it’s perch, it straightens the leg and relaxes the tendon. Come to think of it, that still seems like a remarkable balancing act.

A little over a month ago we wrote about endangered Whooping Cranes, both with information from the 1980’s and an update about their present status. We also included a link to a National Geographic video featuring training flights for the young birds.

Since they were captive-reared, these young Whoopers didn’t know their way from Wisconsin to their wintering grounds in Florida, so they were trained to follow an UltraLite aircraft.

After a 1,234-mile journey taking 76 days, the birds have finally reached their destination at Halpata Tastanaki Preserve in Florida. If you didn’t read the earlier article, here is a link. And another for the must-see video.

Over 50,000 birders — beginners, professionals, and everyone in between — are polishing binoculars, pouring over maps, and getting ready for the 2006-2007 Christmas Bird Count. Last year 57,156 individuals took part in this annual event. That’s quite a change since the first count in 1900, when 27 individuals were involved.

Each year the results of this group effort go into an ever-expanding database that catalogs the rise and fall in the numbers of species of birds across the land. It’s not just the individual species, but also the actual numbers of each type of bird. Although not limited to the United States, last season the US count was 57,357,023 individual birds in 652 species.

Each official counting area is 15 miles in diameter, and the actual count includes every bird found within that area in a specific 24 hour period. The counts must take place between December 14th and January 5th.

Planners of these events make sure that the participants cover all the habitat’s within the count circle, and that some of the searchers are out early enough to catch the owls while they are still active. If there are some hard-to-find birds that have been seen recently, you can be sure someone has staked them out, because if you don’t find them on the official day, it doesn’t count.

If you have never participated in a Christmas Bird Count, it’s a great way to meet fellow birders, whether you have lots of experience or are just starting out. Those with less developed birding skills are paired with seasoned veterans, which is a great way to learn more about bird identification.

To find a bird count near you, including contact information, go the this National Audubon website and enter your state.

The Sibley Guide to Birds

Moving south for the winter isn’t a new idea - we humans were just a little slow catching on. Many creatures migrate to a more comfortable climate each year, but it’s the birds we notice most. Few people who spend time outdoors could fail to notice the disappearance of robins, or the passage of Canada geese, honking their way along avian freeways of the sky.

Bird migration has always fascinated man. Maybe it’s the thought of birds’ freedom to travel where they want - when they want. With a recreational vehicle we duplicate their movements, but the mystery of migration remains.

Like their human counterparts, birds migrate at varying speeds for varying distances. The arctic tern used to be considered the long distance champion. Not satisfied with a single summer each year, it flies all the way to Antarctica for a second summer, making a round trip of 22,000 miles. Now the record seems to be held by the Sooty Shearwater.

A banded ruddy turnstone traveled from Alaska to the Hawaiian Islands in only three-and-a-half days. An even faster trip was that of a lesser yellowlegs. On a 1,900-mile journey from Cape Cod to the West Indies the bird averaged over 300 miles per day.

Since the purpose of migration is to move to a more comfortable climate, the direction doesn’t have to be south. For birds that live on a mountain an alternative direction can simply be down. Mountain quail nest as high as 9,500 feet in the western United States. As cold weather approaches they move at least halfway down the mountain for the winter. But quail, being quail, do it differently. Single file, in small groups, they walk down the mountainside. (Read the rest …)

When we first started birding we went on a migratory hawk watch. Sitting for hours counting tiny specks in the sky, we were amazed when our birding mentors identified birds we could hardly find with our binoculars.

“Bet you can’t identify that one,” we were challenged. It turned out to be a joke – it was a “gas-hawk”, better known as a small airplane. Over the years, as we’ve become accomplished birders, we’ve come up with our own term. We will often identify something, and then correct ourselves. They are usually called a “not-a-bird.”

It might be a coke bottle bobbing in a pond, or a black plastic bag caught on a piece of brush. When you are thinking “bird” it’s amazing the tricks your mind can play. But now we have to worry about Robot Birds.

At California State University, Long Beach, under biological sciences assistant professor Esteban Fernandez-Juricic, students have helped computer-train mechanical birds for some of their experiments. Since it’s rather hard to convince a wild bird to act in a controllable manner, the robots can provide the stimulus, and the experimenters can video-tape the reactions of the real birds.

The robot birds were modeled after male and female house finches, using “decommissioned” bird skins from the school’s Vertebrate Museum. And they are quite realistic. They are sure that the birds are fooled by the substitution.

Some of the experiments test ideas about bird flocking behavior, and they have discovered interesting behavior patterns. For example the closer two birds (or a bird and a robot) are to each other, the more influence the movements of one will have on the other. Have you ever watched the synchronized movements of flocks of shorebirds – how they take to the air in unison, twisting and turning together? This type of flocking behavior is still a puzzle, but gradually it is being solved by studies like these.

As for the photograph, it’s a house finch like they use in their experiments. Not a robot. Yes, I’m sure it’s a bird!

The Sibley Guide to Birds