Are Domestic Cats a Significant Cause of Death in Birds?

A new study published in the Journal of Ornithology ( adds more fuel to the debate about the role of cats in diminishing wildlife populations, and if domestic and feral (those living apart from people) cats should be allowed to roam free at all.  In the new study, catbirds living in suburban Washington, D.C. were tagged with radio transmitters at fledging and followed for several weeks.  The researchers found that domestic cats were the primary predators on young catbirds (Is this the reason they’re called catbirds? No, it’s their mewing calls), resulting in high mortality in some areas.  Of the birds that died from predation, 47% were killed by cats. 

A newspaper article (
written by one of the authors, Peter Marra, claims that “…in some areas less than 15 percent of these fledglings survived, largely because of cat predation.”  Because the birds were tagged with the radio transmitters, they, or their remains, could be tracked and the source of their demise could be determined. This is the first study to determine the causes of death of birds at this vulnerable fledging stage and to show cats as a major source of mortality.

Catbirds aren’t representative of all birds and Washington, D.C. isn’t necessarily representative of bird populations in the entire country, but these results are compelling and they complement many other studies showing that free roaming cats have an impact on wild birds and small mammals. The question is, how big is that influence?        

The American Bird Conservancy claims that cats kill “hundreds of millions of birds” each year in the US although they provide no sources for their estimates.  They urge that owned cats be kept inside and that feral cats not be allowed to roam free but be kept in enclosures, trapped and adopted or euthanized.  Marra says that in the U.S. “…free-ranging cats are as invasive and disruptive to native ecosystems as gypsy moths or West Nile virus.” Many cat lovers will take exception to the comparison with a killer virus.

Free-ranging cat advocates argue that the research is flawed and cats do not represent a significant threat to wildlife. Some believe that cats have a right to roam free and feral populations should not only be allowed to exist but should be supported by people.

It is doubtful that these new results will cause a radical change in policies dealing with free-roaming and feral cats, but they do add more weight to the position of those wanting restrictions on cats roaming at large. 

Many people on both sides of the argument agree that feral cat populations should be managed in some way, not only to control diseases spread by cats, but for the welfare of the cats themselves.  The question is how.  Some believe the only economical and effective way to control feral cats is to trap them all, place them in sanctuaries, adopt them or euthanize them.  Others believe that trapping the feral cats, vaccinating them, spaying or neutering them and then releasing them back into their colonies is an effective and humane way to control their populations. 

A number of people believe that the problem will only be resolved by a combination of strategies, there is no “one size fits all solution”, and that in different areas various combinations of strategies will work better than others.  Both sides agree owners need to be more responsible in caring for their cats so that any outside time is supervised or otherwise managed in order to prevent free-roaming.  Also there is general agreement that free-roaming cat populations could be reduced by eliminating food sources such as unsecured garbage containers and discouraging people from putting out food for strays. What’s your opinion?

You can read a fairly recent review of the controversy and both sides of the argument at these websites.

1 Comment

  • Angela

    Reply Reply

    Having worked with a wildlife Rehabilitator for several years, this is a no brainer. about 99% of animals that "the cat brought in" died of infection within hours even with treatment and not just baby birds, adult birds, rabbits etc all of them. Even when there was no detectable mark. The nature of the skin on these animals and the nature of the cats teeth make puncture marks hard to detect. We saw hundreds of these every year.

Leave A Response

* Denotes Required Field