March 17, 2011
A Birds vs. Cats Blog Showdown
A catbird on her nest, courtesy of Flickr user audreyjm529
While Sarah the cat lover (really, she loves cats; see what I mean?) is busy with another project, she turned the blog over to me, a longtime birder. Heh heh heh.
Now, cats do a fine job providing companionship and keeping a house mouse-free, and few things bring more instant joy to a room than a laundry basket full of kittens. But outdoors, cats are a massively destructive invasive species, among the worst of the invasive mammals. They kill tens of millions of birds each year in Wisconsin alone; they eat endangered North American species such as the piping plover and least tern; and they have driven many bird species to extinction, including the Auckland Island merganser and the Chatham Island fernbird.
The latest measure of their destruction comes from the Smithsonian Migratory Bird Center, which has been tracking birds that live in the urban and suburban areas in and around D.C. Some neighborhoods, like Takoma Park, have a lot of cats roaming the streets. (I’m not an anti-Takoma-Park bigot; some of my best friends live in Takoma Park.) Other neighborhoods, such as Bethesda, have more responsible, considerate and environmentally friendly cat owners that keep their domesticated predators indoors. In a recent study (pdf) in the Journal of Ornithology, Anne Balogh, Thomas Ryder and Peter Marra report that, basically, birds in cat-dense neighborhoods can forget about raising chicks. Working with the unfortunately named catbird (the bird’s call sounds like a meow), the researchers counted eggs, nestlings, adults and fledglings; tagged and radio-collared the birds; monitored their behavior; and counted the bodies. They found that catbird chicks hatch fine, but as soon as they fledge from the nest—bam, the juvenile birds get snapped up by cats. How can the researchers tell which chicks were eaten by cats rather than, say, hawks or squirrels? Cats decapitate their bird prey.
Charming, aren’t they? I’ve tried many methods to keep my neighbors’ outdoor cats away from my yard: squirt guns, tennis balls (lobbed, not pitched that hard), clapping my hands, charging them while waving my hands and hissing. The latter, while least dignified, seems to scare them off the longest. (Ed. note — Sadly, no video of this exists. Yet.) Do you have any tips for keeping the feline monsters away from nature’s finest clade, the birds?
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Thanks for writing about this. If there’s one major thing people can do to aid bird populations, it’s keeping their cats indoors. Cats are lovable creatures (I’m a cat owner, or perhaps servant) but they are also ridiculously good at killing things.
This report like the Marra/Smithsonian article is full of half-truths and bias. For instance, it’s stated that “they (cats) have driven many bird species to extinction, including the Auckland Island merganser and the Chatham Island fernbird.” A quick google search comes up with the complete story “Mainland decline and eventual extinction (of the Auckland Island merganser) occurred with Maori introduction of the Polynesian rat. Following extinction on the mainland, the merganser survived on the bleak but beautiful Auckland Islands. The population started to decline after pigs were introduced to the Auckland Islands in 1807, and cats in 1820. The failed settlement at Port Ross in 1849-1851 probably had an impact on the demise of the merganser…as the settlers had difficulty obtaining food in the harsh conditions, hunted duck. The last known birds were shot on 9 January, by the Earl of Ranfurly.”
Same for the Chatham Island fernbird. Wikipedia: “The reasons for it’s extinction were apparently the brush fires, the overgrazing by goats and rabbits and the predation by rats and feral cats. The last specimen was shot for a collection by Lionel Walter Rothschild in 1895 and it was regarded as extinct by 1900.”
A huge problem with the Smithsonian paper is there was no control group. The scientists took blood samples from the birds and glued radio transmitters to their backs. Probably leaving them compromised, but without a control group, we’ll never know.
My goodness and this nonsense about cats decapitating their prey. Please just a bit of research by the authors would of shown that owls and grackles would have been much more likely suspects than cats. That is, unless that’s not the answer you’re looking for.
Just a few of the articles/books that detail owl prey decapitation:
Bird, D.M., Crouching Raptor, Hidden Danger, in The Backyard Birds Newsletter. 2010, Bird Watcher’s Digest. “There is little you can do to discourage screech-owls if only because they do their killing under cover of darkness. However, you can recognize their handiwork by looking for partially plucked carcasses of songbirds with the heads missing… Corvids—crows, ravens, jays, and magpies—are well known for their raids on birds’ nests to take eggs and nestlings.” Interestingly, the author, David M. Bird, has co-authored another article with Peter Marra.
Thompson, B., The Backyard Bird Watcher’s Answer Guide. 2008: Bird Watcher’s Digest “In urban and suburban settings grackles are the most likely culprits, although jays, magpies, and crows will decapitate small birds, too. Screech-owls and pygmy-owls also decapitate their prey, but, intending to eat them later, they usually cache their victims out of sight.”
The Marin County breeding bird atlas, W. David Shuford, Point Reyes Bird Observatory, 1993, 475 pages
Snippet: “Year round, Spotted Owls regularly cashe decapitated and partially eaten remains of excess prey and later retrieve them. They securely wedge the remains for storage on top of limbs in trees or on the ground beside logs, trees…”
Live blind snakes in eastern screech owl nests: a novel commensalism. F.R. Gehlback and R.S. Baldridge, 1987, Oecologia, Vol 71, No. 4. “Like most raptorial birds, eastern screech owls kill and usually decapitate vertebrate prey before bringing it to nests.”
Caching behavior of screech owls in Indiana ,JB Cope – The Wilson Bulletin, 1978
“Twenty-two dead chicks, 7 decapitated, were found on a shelf near the ceiling of the enclosure.”
I’d like to clarify/correct a few points here…
Regarding the “tens of millions of birds [killed by cats] each year in Wisconsin alone,” you and your readers might be interested to know that there actually was no “Wisconsin Study,” as it’s often called–not in the scientific, peer-reviewed-publication sense. The often-cited “estimates”–which have, over the past 15 years, taken on mythical status–were nothing more than biased, back-of-the envelopes guesses.
Indeed, co-author Stanley Temple himself admitted that their figures weren’t “actual data,” though the American Bird Conservancy (ABC), U.S. Fish & Wildlife (USFWS), and others— continue treating these figures as if they were actual data. “That was just our projection to show how bad it might be,” noted Temple.
But Temple wasn’t as forthright about the origins of their “estimates.” The authors’ “intermediate” estimate, for example, was–in addition to its several flawed assumptions– based on the hunting habits of a single rural cat in Virginia. And their high estimate was even less sound.
To your comments about the catbird research—again, you’re doing your readers a disservice.
“The juvenile birds get snapped up by cats”? Actually, the researchers witnessed exactly SIX catbird deaths due to predation by cats. Six of 42 total mortalities.
They attributed THREE more to cats on the basis of decapitated remains because, as they explain, “we are unaware of any other native or non-native predator that regularly decapitates birds while leaving the body uneaten.”
In fact, it’s rather widely known that such predatory behavior is not at all uncommon with owls, grackles, jays, magpies, and even raccoons.
Something else Marra and his colleagues fail to acknowledge (let’s face it: it does kind of ruin the story) is how well gray catbirds are actually doing in the area. The North American Breeding Bird Survey indicates that Maryland’s gray catbird population has increased about 9 percent between 1966–2009, a period during which the state’s human population grew approximately 57 percent. And data from BBS Route 46110, the nearest to the research sites, also trend upward in recent years.
Even the Smithsonian Migratory Bird Center, Marra’s employer, suggests the outlook for the catbird population is quite good: “To thrive in these [fragmented] habitats birds must have special adaptations such as the ability to respond to frequent nest predation and parasitism and to forage on a wide variety of seasonally available foods. Armed with these adaptations, catbirds are well prepared for the disturbed habitats of the 21st century’s fragmented landscape.”
Given how poorly the Smithsonian has covered this story (beginning last October), it’s difficult not to conclude that the people involved are far more interested in perpetuating the shameful witch hunt against feral cats than they are in promoting rigorous scientific inquiry.
Peter J. Wolf
http://www.voxfelina.com
The real issue, as wildlife biologist Roger Tabor put it, is whether prey populations can sustain the predation.
On continents, prey species have survived predation for centuries. In fact “The State of the Birds Report 2009” states: “The urban/suburban indicator, based on data for 114 native bird species, shows a steady, strong increase during the past 40 years…”
FOLKS, THIS HAS TO BE HIGHLIGHTED: IT IS A MOST IMPORTANT ASPECT OF THE CAT PREDATION AND BIRDS-IN-DECLINE ISSUE.
The truth is that most feral cats live in urban and suburban areas, and yet urban birds continue to increase. The truth is that feral cats have a propensity to scavenge from human trash, plus of course when humans see them scavenging, they put out cat food. Plus the cat is a rodent specialist and even when he has to hunt to fend for himself, small mammals are much easier for him to catch.
Bird populations in urban areas have been increasing each and every year for 40 years, and for years before that urban birds population numbers remained the same, so I dont think we need to worry that cats are causing the extinction of birds in our backyards.
We are NOT opposed to keeping cats indoors, but we protect and defend feral cats and implement TNR–Trap-neuter-return as a sound, humane, ethical method of control. At NO COST to cities and towns….the caretakers and feral cat groups pick up the tab.
My 15 year old cat is mostly an indoor cat but she does like to wander outside while I’m in the garden. She hates other cats that sometimes wander into the garden while she is out there, and she will hiss at them so I’ll run them off.
We have a lot of yard birds that are attracted to our bird feeders. If birds could laugh they’d be laughing at my old cat for she will nap with one eye open as they flit around her; they are not intimidated by her in the least. I actually have to protect the cat when the mockingbird is around.
It is sad to find a dead bird in the yard and I have found several over the years. It is especially sad when it is a baby or juvenile bird. It seems that the big crows prey on the baby birds more than any neighbor cats, but I’m not always there to watch the situation, so I’m sure some cats do succeed in ensnaring a young bird.
Mother Nature does seem to have a way of balancing the natural order of things…at least as far as my backyard goes.
I do know that cats can leave an offending odor in the garden and I do try and discourage strange cats from wandering in. I have heard of people sticking plastic forks upside down into the ground to discourage cats from squatting. This is not an attractive option IMO.
[...] to what Laura might have implied yesterday, I’m not anti-bird. And to prove it, I present to you one of the finalists in the Natural [...]
I made an error in my earlier comment. I said the radio transmitters were “glued” to the bird’s bodys. Not so, the radio transmitters were harnessed to the birds bodies with 1-mm elastic thread. Since the radio transmitters were not removed from the surviving birds, I can only imagine the painful, lingering death from the harness cutting into their bodies as they grew.
[...] while perusing the shelves of my bird-crazy colleague Laura, I came across “Winged Wonders: A Celebration of Birds in Human History,” by Peter [...]
The data from the study really don’t support the conclusions people are drawing. Only 6 of 42 dead birds were killed by cats. And even with those, there’s no way of telling whether they were “thinning the herd” — catching the weakest or least wary birds, which would have been caught by other predators instead.
There’s an analysis here: http://sutroforest.com/2011/04/09/cats-catbirds-why-the-smithsonian-study-doesnt-say-what-everyone-thinks-it-does/
I had a problem bird-hunting cat who killed many birds to my disgust. In desperation, I tried a new solution: I made a brightly colored fabric “ruff” and threaded a collar through it. With his neck ringed in bright fabric, my cat couldn’t capture birds any more! The reason: Songbirds see bright colors extremely well and in low light. Their eye anatomy results in them keying on bright colors. They see the cat easily, ringed in bright fabric, and they fly off instantly. My cat retired from bird-hunting.
After one year of no-more-dead-birds, I named it the Birdsbesafe Cat Collar in 2009. Cats should stay indoors, ideally, but if they don’t, you may have a new option that you should learn about. Peace, Nancy
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I am a wildlife rehabber and big animal lover. I have cats, but also find them to be the biggest cause to compromised animals I take in each year; birds especially. Young mammals and birds have less than a 50% chance of surviving when cat caught. Cats have a very veneomous bit that causes rapid infection in it’s victim (ever been bit or scrtched by one?). So even if it does make it for a coupld days, it suffers painfully and more often than not… things end badly. And those thousands are just the ones that end up in local rescue facilities. Please keep cats in. If not, might want to check on out birdbegone collars. Not sure how effective they are.
Opp.. birdsbesafe not be gone. Probably does not help fledglings too much though.
What can be done if it’s cats’ instinc to hunt and catch birds.
Commenter #14 asks what can be done if it is the cat” instinct to hunt and catch birds? The answer: Be a responsible pet owner and keep one’s cat indoors or stay with the cat when it is allowed in one’s yard.
I am a responsible cat owner. All of the cats I own live indoors. All of them previously feral. They are all fixed, have their shots and don’t go outside. Those that I cannot take in, I feed and water. Feral cats are an unfortunate circumstance due to humans. It is beyond reprehensible to give some sort of credence to those “humans” who are so brazen as to justify poisoning these unfortunates. These people are mentally ill. They are themselves unfortunate. Should we poison them? It would be more justified as the feral cat is just trying to survive, as opposed to being self important psuedo-scientists. I am disappointed in the Smithsonian. If you are this irresponsible in publishing this crap, please provide the information so I can cancel my subscription to your magazine. Why not just own up to the fact that someone got a little lazy, pretentious and sloppy at the very least? Isn’t it up to humans to be more responsible? Let me help you with that. Yes, yes it is.