DEAR JOAN: I have been reading a lot in the media about all the birds killed by feral cats. Have any studies been done that show how many birds are killed by pesticides? I would think it would be more than those killed by cats. Eating bugs or seeds sprayed by weed killers would account for a lot. Anyway, I hate to blame cats for the bird population going down.
DEAR LYNDA: Although outdoor cats -- feral and house cats allowed to roam -- do serious damage, they are not the biggest threat to bird populations. That dishonor goes to the loss of habitat.
The destruction of rain forests, the harvesting of trees, urban sprawl, the loss of marshes and the draining of swamps, and dozens of other changes to the landscape have had huge impacts on bird populations for decades.
Even the construction of highways can have an effect by dividing the land and creating smaller habitat areas.
Pollution also has taken a toll. The use of DDT weakened the shells of nesting birds and although the pesticide is banned, the losses still have an impact. And then there is the occasional ecological mishap involving oil spills that kill thousands of seabirds and spoil their nesting grounds.
About 400,000 birds are killed each year when they fly into windmills; up to 1 billion die by flying into windows of high rises and other buildings. Seabirds get tangled in fishing nets; hunters kill thousands each year; more than 170 million are killed by electrocution on power lines; almost 70 million are killed by pesticides.
Drawing the most attention these days, however, is the cat issue. It's a highly emotional subject that involves people who love cats and people who love birds, and those of us who love both.
A recently released study conducted by the Smithsonian's Conservation Biology Institute and U.S. Fish and Wildlife Service rekindled the argument about the threats outdoor cats are causing.
Researchers set the number of birds killed by cats in the 48 contiguous states at 1.4 billion to 3.7 billion. The estimated toll on small mammals -- mice, rats, rabbits, voles and shrews -- at 6.9 billion to 20.7 billion.
The majority of the cats involved are feral, although house cats that wander the outdoors kill their share of birds, too.
Most of the heat in this debate centers primarily on feral cats. Some have suggested killing the cats to protect the birds, an idea that has met vocal opposition.
There are attempts to reduce the number of feral cats in a slower but more humane manner, using something called TNR: trap, neuter, release.
TNR is helping, but it doesn't address the issue of feral cats killing birds and small animals in order to survive.
As for the house cats, there are people like me who encourage cat owners to keep their pets indoors where they can neither be hunter nor prey.
But there are many people who believe cats need to roam free and exercise their hunting instincts. We already neuter them and in some cases, declaw them. Should we also take away their inherent skills as hunters?
There is a case to be made for both sides, and while I love cats, I think birds, which already face tremendous threats, need to win the debate.
There are species of birds that are facing extinction and some that already have disappeared off the planet. We need to find solutions, and the first step is to control our pets.
Joan Morris' column runs five days a week in print and online. Contact her at email@example.com; or P.O. Box 8099, Walnut Creek, CA 94596.