Sea otters – those fantastically adorable, overgrown weasels of the kelp – are highlights of any sightseeing trip along the California coast. But recent years have seen dozens die of toxoplasmosis, a parasite that reproduces in cats and causes neurological problems when it finds its way into otters. That happens when parasite eggs contained in cat feces wash into the ocean, scientists think.
The evidence was always fairly circumstantial – a 2005 San Jose Mercury News article (reposted here) noted that the town of Morro Bay, California, had the state’s highest concentration of otter deaths two years running. At the same time, the town is home to a sewage plant that discharges a million gallons of sewage per day containing up to 7 times more suspended solids than plants in other California cities (well above an EPA limit, but still legal thanks to a 1977 grandfathering agreement, the article says). Still, scientifically speaking, that’s a fairly tenuous link.
Which is why I was so pleased to see an article in the Journal of the American Veterinary Medical Association that went a step or two farther. They polled residents of Morro Bay, as well as nearby Los Osos and Cayucos, and estimated how many cats were out there and how much cat dung they were producing. The results are fairly astounding, especially if you are not really a cat person.
The three towns had an estimated 9,300 cats (more than 20 percent of them feral!). Cats lived in 38 percent of the area’s households, with an average of 1.9 per cat-containing house, which if you ask me is a lot of cats to have walking in front of the TV every time you try to watch a movie.
Worse, the survey suggested that even non-feral cats get outside often enough to contribute 75 percent of their bowel movements into the local greenery rather than in their kitty litter. The final estimate for annual outdoor cat dung deposition was 107.6 metric tons (78 tons of that came from domestic cats). Which strikes me as an awfully large heap of cat poo for three fairly small towns.
I’m always fascinated by these kinds of bulk estimates of our cumulative impact on the landscape – particularly when they’re large enough to be mind-blowing but still small enough to grasp. Just try to imagine the combined, shall we say, “throughput” of all the cats in the whole U.S. And while it’s still not a quantitative link from crapping cats to dead otters, it strikes me as a good argument for three precautions: Keep your cats inside (this will keep local birds alive, too). Don’t flush your kitty litter, even if it’s touted as flushable. And work to reduce feral cat populations (or at least stop putting out kibble for them).
And while this may sound glib coming from your admittedly cat-averse Scribbler, take heart that cats.about.com agrees.
(The basic cats – toxoplasmosis – otters story had tons of press last year – here’s NOAA, the BBC, Nat. Geo., Time (PDF here) and LiveScience for starters.)
Yikes. And I thought I was doing a good thing by switching to flushable litter!
Yep, it’s extremely important to train your cat to do all its business in the litter box if you are lucky enough to live along the California coast. Bag it up tightly, too. Unfortunately raccoons (and possibly oppossums?) carry the parasite too. I live in Santa Cruz and love our otters! Without them the sea urchin population would eventually explode and gobble up the spectacular giant kelp forests of the Monterey Bay National Marine Sanctuary… your website rocks, scribbler!
ps you don’t hurt cats do you?
Hi Deb, Don’t worry, the Scribbler is much too gentle to hurt cats – and will even grudgingly pet them whenever they climb into his lap. Thanks for reading!