Eleven-year-old Paula Everett didn’t intend to ruffle any feathers when she picked up a fledgling crow that had fallen out of its nest and began carrying it home to her mother, who nurses injured birds.
But a flock of protective adult crows grabbed rocks from the gravel roof of a house and began dropping the stones on the girl’s head. “Mom, the crows are throwing rocks at me,” she complained when she ran into the house, recalled her mother, Judy Everett.
The avian assault in the San Gabriel Valley illustrates a fact of modern life in America’s cities. Big, black, loud, mischievous and intelligent, crows are everywhere.
Taste for McDonald’s
The birds were once dynamited out of their roosts by the thousands. Now crows and their relatives are prospering as the uninvited guests of their historic enemy, man.
While they haven’t yet become the national bird of suburbia, crows seem ubiquitous in the unnatural “forests” around big cities, where they have developed a taste for McDonald’s french fries, birthday cake and cat food.
The crow population in California is growing a brisk 4% a year, according to the federal Breeding Bird Survey. Once shy of man, there are now thousands of crows in residential areas of Orange County and the San Fernando and San Gabriel valleys, according to expert estimates.
“In Irvine we’ve gone from no crows” to the point where they are “one of our most common birds,” said H. Lee Jones, a member of survey team for the U.S. Fish and Wildlife Service.
Ravens, larger cousins of the crow and once thought to be in decline, are reproducing so rapidly in Southern California that biologists want to poison or shoot them to save the desert tortoise. Audubon Society volunteers counted 293 ravens, once a rare sight, in the Malibu area in 1987.
“The population is exploding. It’s kind of like Bangladesh,” said Dan Taylor, western regional representative for the National Audubon Society in Sacramento. Actually, while both species are increasing, California’s crow population is growing a third faster than the human population in Bangladesh.
Daryl Brun of Blue Diamond Growers in Sacramento said nut growers look forward to the arrival of crows at certain times of the year because they clean the trees of “mummies,” worthless fruit that stays on the trees over the winter. But the crow population is accelerating so fast in the San Joaquin Valley--13% a year--that farmers are beginning to complain, according to Cosmo Insalaco, the Fresno County agricultural commissioner.
The population boom parallels a growing appreciation of crows and ravens as eggheads of the feathered world. They learn faster than some monkeys and are able to use tools. An instructor at UC Davis published a paper several years ago in which he suggested that campus crows were purposely dropping walnuts on the road in front of cars, inventing the world’s first gasoline-powered nutcrackers.
A behavioral ecologist at UCLA who has observed 40 families of tagged birds in the San ernando Valley for 4 years thinks she has seen even more complex activities.
“They have definite personalities, and they also have friends, and that’s unheard of outside primates,” said Carolee Caffrey, who is working toward a doctorate in crow behavior.
Once upon a time, the shaggy-headed ravens were seen infrequently, picking over animal carcasses on the desert or in the mountains. Crows were found out in the country, harassing farmers, though often in big numbers. A flock estimated as big as 1 million destroyed a promising almond industry in Klickitat County, Wash., in 1926.
Such attacks made man declare war on the birds. Communities began dynamiting the huge Midwestern roosts at night. In Illinois 40 years ago, 328,000 crows were killed before a flock abandoned its rural roost.
Susan Drennan, editor of American Birds magazine, said crows migrated to cities after World War II. Bird experts suggest that laws against shooting guns within city limits may have contributed to the movement. Then in 1972, Mexico insisted that crows and their relatives in the corvidae family be added to the list of species protected by the Migratory Bird Treaty Act, which made the city streets safer than ever for the birds.
“One of the messages we’re getting is that crows are increasingly becoming birds of suburban and urban areas,” said Charles Smith, director of Special Projects for the Laboratory of Ornithology at Cornell University in Ithaca, N.Y. “There are plenty of scraps for them from human activities, whether it’s from the local McDonald’s or the bakery.”
Richard Knight, an assistant professor at Colorado State University, found in 1985 that when he approached the nests of urban crows, they simply sat there watching. Rural crows always took wing. Knight concluded, “Our results suggest that recent colonization of cities by nesting crows may be in part a response to different levels of persecution in urban and rural areas.”
The most reliable indicator of bird trends is the Breeding Bird Survey of the U.S. Fish and Wildlife Service, a census taken since 1965 in 25-mile corridors throughout the nation. The survey indicates that California’s crow population has grown rapidly as suburbs expanded and new urban “woodlands” were created.
The Audubon Society’s annual Christmas Bird Count has tallied crows, ravens and other species for several decades. While some experts caution that it is subject to wide fluctuations based on the number of volunteers used and other things, the Audubon Society says the survey can reflect bird population trends. The Christmas Bird Count since 1946 in Orange County, which has seen a tremendous growth in human habitation, shows a steadily upward trend among crows.
Once it was assumed that a large black bird in an urban area was a crow. “But now you can’t say that anymore, because ravens are moving in,” said Kristin Berry, a wildlife biologist for the Bureau of Land Management. They can now be seen nesting on buildings in downtown Los Angeles.
The U.S. raven population has grown 3% yearly for 2 decades. Ravens are becoming so numerous that wildlife officials have drafted a proposal calling for poisoning and, perhaps, shooting hundreds of them in the Mojave Desert to save the desert tortoise, which is proposed for federal protection as an endangered species. The shells of 250 young tortoises have been found around the nest of just one pair of ravens.
Some experts fear the population explosion will damage other bird species. “It’s going to go very hard on the songbirds,” whose nests are raided by crows, said Lloyd Kiff, curator of Ornithology at the Los Angeles County Museum of Natural History.
Other experts, however, said they have seen no evidence that urban crows are driving out other birds.
Looks Belie Brains
Bird intelligence is a subject of debate. The fact that a meadowlark will attack a stuffed rival placed in its territory doesn’t do much for its reputation. But Jones believes that “we don’t give birds enough credit,” in part because “they don’t look very much like us.”
Recent studies are challenging assumptions that birds are simple creatures. A study of crow vocalization at the University of Maryland showed that the simple “caw” is used in a variety of ways to signal alert, approaching danger, alarm and all clear. Different social groups have different songs, and when new members join the group, the song changes.
When it comes to complex behavior, “we’re finding out that we as humans don’t have a corner on the market,” said Cornell’s Smith.
Knight said crows often outscore dogs on learning tests. Humans might have a lot higher opinion of bird intelligence if the first work on birds had been done on crows instead of pigeons, Knight said.