Why Some Wildlife Populations are Growing

Saturday, July 6, 2002
By MIKE LEWIS
SEATTLE POST-INTELLIGENCER REPORTER

The complaints to animal control come more regularly than ever before, both in the fingers of residential development that reach into the Cascades as well as from downtown Seattle:

· Raccoons overturning the trash in Edmonds.

· Crow cacophonies enraging day sleepers in the U District.

· Coyotes brunching on housecats in Snohomish.

· Pink-eyed opossums teetering along fence tops everywhere (and, in the late-night haze of repulsed homeowners, sometimes reported as giant, lumbering rats).

Experts expect such encounters to increase -- along with the decline in sighting of weasels, winter wrens and shrew moles. It seems that while certain animals suffer from human contact, those that are highly adaptable, sometimes smart and relatively tough, are thriving.

Call it Survival of the Blandest. Or, in harsher terms: Eat trash or die.

Much attention has been paid to the human-caused decline of flora and fauna
and not the increase in other species -- until recently.

"It's an area of intense study," said Stephen West, professor of wildlife science at the University of Washington. "These populations are just exploding worldwide."

Scientists call these populations of plants and animals "weeds" for their ability to adapt, survive and thrive anywhere. In every major city worldwide, regardless of climate, three populations of birds are thriving: sparrows, pigeons and starlings. Move outside the cities and these populations plummet.

"They've traded salmonberry for KFC," said Jim Marzluff, a University of Washington ornithologist and crow expert. "This is what you get when you change a habitat."

The soaring crow population, Marzluff said, would drop if humans disappeared from the Puget Sound region, home to one of the largest urban crow populations in the world. Same with rats.

Crows eat trash, love dumps, are among the most highly intelligent birds and don't have any urban predators. They like open spaces, and humans are good at creating those. It's not that crows arrived with people as did the English sparrow. We've inadvertently created good crow habitat.

"Crows were here in the Pacific Northwest before humans evolved," Marzluff said. "But we've helped them plenty."

The same is true with coyotes. Before the aggressive clearing of core interior forest -- the type of old, dense forest with few clearings -- the coastal Pacific Northwest was a lousy coyote habitat. So few coyotes hung around. But add open Dumpsters, landfills, cleared space and small, tasty domesticated tabbies, and coyotes moved in to stay. They've been seen in downtown Seattle, along Lake Washington and in Discovery Park.

"Coyotes have been of primary concern as we go into spring and summer," said Ben Leifer, manager of King County Animal Control."That's when they are mating and breeding. We've gotten some reports of missing small domestic animals."

The populations of raccoons, opossums, mice, rats, starlings, pigeons, scotchbroom and strains of bacteria are also soaring. Everywhere humans have stacked the survival deck in their favor, they are out-competing natives.

But another strange thing is happening as well, scientists say. These species, in some cases, are showing alteration in their evolutionary tracks toward that adaptation. In other words, some creatures now appear to be showing signs of very specific adaptation to human interaction.

In his book "The Evolution Explosion," Harvard biology professor Stephen Palumbi wrote that our effect on nature isn't limited to what we eliminate, but also what paths we alter. "The species that can live with us -- and on us -- have learned to rapidly adapt to the conditions we've created," he said in a recent interview.

Farmers and doctors have known this for decades. Plants and animals are bred for production. Insect, virus and bacteria populations rapidly evolve to resist chemical attack as only the most hardy populations survive and reproduce, rendering those attacks obsolete and creating superbugs.

But it's happening outside of human control. Take salmon, Palumbi said. "We know that intensive fishing changes the way they live their lives," he said.

In one study at British Columbia's Nanaimo Lab, scientists discovered that heavy gill-net fishing over decades has led to an unexpected change in the native pink salmon stock. Because the nets entangle large adult salmon, the population over time has been artificially selected toward smaller, slower-growing and tubular-shaped fish that more readily slip through the nets. What's more, the fish now reproduce at a younger age in a natural balancing effort to keep the populations up.

Fish, insects and bacteria, he said, make perfect case studies of how humans can change an evolutionary track. They reproduce rapidly and in large numbers, so generations of change can be observed.

But is it happening to the other generalist species that scientists call "symbionts" or "commensals," those that have linked their health to humans? Are some species becoming generalists in order to survive? Is the world moving toward plants and animals that are nature's equivalent of the general-purpose strip mall?

"It's a fascinating area, those that live with us but we don't control the breeding," Palumbi said. "The organism that can do well is flexible, and can deal with a very disrupted landscape. "

Some animals, scientists note tongue in cheek, have shown human traits. Crows commute daily to feed in landfills as far as 30 kilometers from their nests. Coyotes and black bears appear to know when trash day is and show up early for the best pickings.

Palumbi wonders if species like the wharf rat and house mouse might have evolved distinct traits from their ancestors so they could adapt to live with humans, sort of like how the sparrows on a rhino's back evolved. But if that is the case, look at which population is thriving today. Rhinos reproduce slowly and have very specific needs. The generalists on their backs don't.

As humans alter their environment to favor the generalists, Palumbi notes, "extinction is what happens if a species can't evolve fast enough."

P-I reporter Mike Lewis can be reached at 206-448-8140 or
mikelewis@seattlepi.com

Stephen Vantassel is a Certified Wildlife Control Professional. He is a nationally known writer including having been an assistant editor for Wildlife Control Technology magazine, author of numerous ADC articles as well as The Wildlife Removal Handbook rev.ed and the Wildlife Damage Inspection Handbook rev. ed. Mr. Vantassel is also a vocal critic of the growing animal rights movement. He has exposed the fallacies and deceptions of the animal rights protest industry through debate, lecture and publication.

Disclaimer: WDC seeks to provide accurate, effective and responsible information on resolving human/wildlife conflicts. We welcome suggestions, criticisms to help us achieve this goal. The information provided is for informational purposes only and users of the information use it at their own risk. The reader must consult state/federal officials to determine the legality of any technique in the reader's locale. Some techniques are dangerous to the user and to others. WDC encourages readers to obtain appropriate training (see our informational literature at our Store ), possib6:43 PM 4/19/2006ly hire a professional (for help in finding one e-mail after visiting the previous link) and understand that proper animal damage control involves patience, understanding that not every technique/method works for every situation or even 100% of the time. Your use of this information is governed by this understanding. We welcome potential users of the information and photos to simply ask for permission via e-mail. Finally, WDC welcomes e-mail but understand that all e-mails become property of Wildlife Damage Control.

7/11/02

Disclaimer: WDC seeks to provide accurate, effective and responsible information on resolving human/wildlife conflicts. We welcome suggestions, criticisms to help us achieve this goal. The information provided is for informational purposes only and users of the information use it at their own risk. The reader must consult state/federal officials to determine the legality of any technique in the reader's locale. Some techniques are dangerous to the user and to others. WDC encourages readers to obtain appropriate training (see our informational literature at our Store ), and understand that proper animal damage control involves patience, understanding that not every technique/method works for every situation or even 100% of the time. Your use of this information is governed by this understanding. We welcome potential users of the information and photos to simply ask for permission via e-mail. Finally, WDC welcomes e-mail but understand that all e-mails become property of Wildlife Damage Control.