Tuesday, November 21, 2006

Birds and the Art of War

There is wisdom in an owl sitting motionless in a tree, wisdom and a lesson to be learned.

It was a seemingly quiet morning. A few mourning doves and house finches dabbled at the feeder. A band-tailed pigeon perched on the precarious tip of a slender cypress along a nearby driveway. Up the hill in the neighbor’s yard, a lone scrub jay called with urgency.

The jay’s alarm squawks became frantic, a second scrub jay joined in. Then a harsh “caw” took up the warning. Within minutes a single crow became a mob of 20.

High in the upper branches of a young eucalyptus tree perched a dark brown figure. Crows rushed the dark villain. Their sleek black bodies plunged toward the still figure but always maintained a safe six-foot distance. Other crows sat like glossy sentinels in adjoining trees cawing raspy threats. The air became a kaleidoscope of black wings and pointed beaks.

At first I thought one of the red-shouldered hawks was using the tree as a vantage point; frequently crows will mob a hawk and drive it off. But the shadowy bird in the tree didn’t move, didn’t give any ground.

The crows grew to a murder of 40. Black voices raked through the air.

This threat was personal, it was a great horned owl.

HEAR the Crow Alarm Calls.

The great horned owl is one of the few creatures that poses a threat to crows. In the dark of night, this large bird of prey can steal a sleeping crow right off its perch. Identifying danger in their midst, the crows were determined to drive away the predator while the light of day still offered them protection.

And here is where the situation became more than just black birds squawking. Typically, scrub jays do not share space with crows by choice. Crows, after all, are known to take the hatchlings of smaller birds as food for their own youngsters. Similarly, crows and ravens compete for territory. I have watched the local family of 15 - 20 crows mob the pair of ravens that have been checking out real estate in our neighborhood. Jays, crows and ravens are all intelligent birds and they prefer to keep their distance from the competition.

But in the owl, these birds had a common foe. The pair of scrub jays did not have the size or number to drive off the great horned owl. The jays not only attracted the attention of the crows, they continued to work alongside the crows aiding in the harassing cacophony. The crows sent for reinforcements, extended family members arrived, expanding their usual number well beyond 40. If the mob could press the owl out of the tree and into the air, they could drive it off, chase it out of their territory.

After an hour of constant effort, most of the crows moved on. But the owl was not forgotten, four stouthearted defenders perched in the tree encircling the threat. Throughout the day, crows arrived to take their turn at the watch.

The owl moved closer to the tree trunk, its tawny feet with dagger-like talons gripping the smooth gum bark.

By 3:00 PM the day was slipping away. The approaching night brought renewed urgency. The black mass returned and they brought with them the calvary, ravens. Bigger and bolder, one raven flew right into the treetop. With menace it croaked and waved its pointed beak within a foot of the owl. Several times it rushed the quiet predator, while crows raucously filled the air. Still, the owl did not move.

Here it was, two forces in direct opposition. Each side knew themselves and their abilities. The jays, crows and ravens looked danger in the face and declared its presence. They put aside their conflicts of similarity and banded together against a shared threat. The crows had the strength of numbers. If they could maintain their harassment of the enemy, they might be able to unsettle the owl, press it to make a mistake and take to the air. On the wing in daylight, the owl would be playing by the crows’ rules, they might gain the upper hand.

But the owl knew the best strategy for a lone predator was patience. Its back was safely against the tree trunk. Its sharp talons and beak posed a great enough threat to keep even the large raven at bay. If the owl could maintain its position, it was safe. The harassment and threats never ruffled its soft brown feathers.

On this day the owl prevailed, it stayed on its eucalyptus perch until evening drove the crows to roost.

Know your enemy and know yourself. Fight your battle, not your opponents. Study the travails of others, bird or human, strategy is strategy.

Wednesday, November 08, 2006

Project FeederWatch

It’s that time of year again! Not Halloween, not autumn, not back-to-school.

It is FeederWatch time!

All across North America, backyard scientists are cleaning up their bird feeders, restocking their bird seed and preparing for a winter of counting native birds for Cornell University’s Project FeederWatch.

Project FeederWatch offers a unique opportunity for anyone with a willingness to participate: the chance to be a citizen scientist collecting valuable scientific data on wild birds. In backyards and school yards across the continent, people like you are vital to gathering information on migratory bird movement and population density.

Field biologists can only be in a limited number of locations, informed citizens can provide valuable eyes and ears for science. Data collected by school children and birding hobbyists for Project FeederWatch has identified specific bird species expanding their territory north in response to climate change. Last year varied thrushes were documented further east than ever before and western hummingbird species were spotted on the east coast. Observations at bird feeders typically identify the first outbreaks of avian disease and provide vital information on the pattern by which the disease spreads.

Scientists around the world use Project FeederWatch’s 20 years of data to study population cycles, migration patterns and the effects of human activity on the natural world.

Can you make a difference counting birds visiting a feeder on your apartment balcony? YES!

When your sightings are combined with those of thousands of other FeederWatchers, every bird you see, or don’t see, helps scientists have a more complete picture of bird populations across the country.

Even if you are just beginning to recognize your local birds, your observations are valuable. In October I gave a workshop on how to participate in Project FeederWatcher at the Wild Birds Unlimited store in Woodland Hills, CA.

In its 20th year, Project FeederWatch needs you more than ever. Whether you count on a ranch, an office balcony or a school yard, information on wild birds is vital to understanding the effects of global warming, how avian flu might travel across the country and, most importantly, the health of our planet. Wild birds travel around the globe, they are “the canaries in the coal mine.”

The effect of West Nile virus is decreasing in my neighborhood. How do I know? Because I have been a FeederWatcher for six years. We went from seeing scrub jays every time we counted to recording NONE for 2 years. Now, we see an occasional young pair. The scrub jays are making a come back. The ruby-crowned kinglet has returned for the winter, but this time it has a friend. I have come to know the birds that visit my yard as neighbors and individuals. Get to know your wild neighbors and Make A Difference–count birds for Project FeederWatch.

To learn more about Project FeederWatch or to register, visit www.birds.cornell.edu/pfw or call the Lab toll-free at (800) 843-2473. In return for the $15 fee that supports the program ($12 for Lab members) participants receive the FeederWatcher’s Handbook, a poster of the most common feeder birds, a calendar, complete instructions, a subscription to Cornell Lab of Ornithology’s newsletter, BirdScope, and the FeederWatch Winter Bird Highlights. The season runs from November 11 to April 6, and participants may join at any time.

It’s our 20th year, and we’re counting on citizen scientists to help us track birds for the next 20 years.