Sunday, August 19, 2012

Catbird Seats

Cats as hunters  have raised considerable interest about breeding hunting out of house tabbies at Rabett Run, but the real problems are feral cats, and the real serious problem is feral cats on remote islands.  Birds, of course can fly, often considerable distances and over the eons have populated remote islands which mammals can't swim to.  OTOH, they can hitch rides with people in boats and they have done so with a vengeance, none more successfully than Brother Rat and Sister Cat, and to an extent Cousin Rabett. 

Birds on these islands have, again over the eons, have lost their native caution of hunting animals and protecting their nests and eggs from other beasts.  It is only relatively recently that eradication programs have started to rid some of these islands of the feline predators, but it is not a trivial thing.  Kill the cats, and you have the rats which are harder to get rid of and breed like crazy.  This is, also true of rabbits who leave the birds alone but eat the leaves down to the soil.

Feral cats do not seem to become well established in areas with “mesopredators” which
either compete with or prey upon cats. In New Zealand, Taylor (1984) suggests that stoats (Mustela erminea) outcompete feral cats, restricting their presence to larger islands and to areas either with rabbits or close to human habitation. Coyotes (Canis latrans) control cats in coastal southern California (Crooks and Soule 1999).
Coyotes, as Kevin Drum discovered to his dismay, like cat treats.  Since humans bond with cats this is often hard on the humans, but when too many cats disappear it does not go well for the coyotes.  There is a considerable literature on all this.

20 comments:

Anonymous said...

It's interesting how Australian ecology differs from the ecologies of other continents, in terms of the nature of its trophic webs.

The geological isolation of Australia, together with its ancient, nutrient-poor soils, mean that there is a great skew toward the lower trophic levels: that is, there ain't much room for a large biomass of top predators on the continent. In addition, over the recent but pre-human geological period predation was conducted more by reptiles and by birds than by mammals, compared to the other continents - this in itself is a reflection of the previously-mentioned isolated and impoverished character of Australia.

Of course, humans screwed it all up with dogs and rats, although it's interesting to see that over a period of tens of thousands of years the rats effectively speciated and became 'neonatives'. In the process though many original naïve Australian species were driven to extinction, including the largely dingo-driven loss of devils and thylacines from the Australian mainland.

The Europeans, late to the party but with a chestful of extra exotics, have presided over one of the most remarkable extinctions of indigenous mammals anywhere in the world. Foxes and cats especially have been more effective agents of extinction than dingos and aboriginal humans, and Europeans themselves have profoundly altered the landscape by removing much habitat.

And it's not finished yet, as the impacts of our exotic introductions and habitat destruction have incurred an extinction debt that will continue to be repaid in the decades and centuries to come. There are certainly ways that we could minimise the damage, but some of the approaches are likely to be different from those that would work overseas.

Anyway you look at it though, Sylvester needs to be whacked if the worst is to be avoided.


Bernard J. Hyphen-Anonymous XVII, Esq.

Anonymous said...

Two more points...

With the ~90% decrease of devils over the last decade, feral cat numbers have greatly increased. Devils do not prey on cats directly, so the increase probably reflects the fact that there is much more carrion for the feral cats to source. This results in a sustaining of elevated cat numbers that then impacts severely on species that form part of the cats' prey diet, and in Tasmania that includes a wide range of already-endangered native/endemic birds and mammals.

The introduced predator/prey combination has been used by some to argue that cats should not have been eradicated from Macquarie Island. However even though the cats were in a semblance of a balance with the rats and rabbits, all three species were still greatly impacting the natives. What might have been a better strategy would have been to target the rodents such that their numbers declined simultaneously with the cats.


Bernard J. Hyphen-Anonymous XVII, Esq.

John Mashey said...

Well, one could try some really clever species introduction, like cane toads.

Oz is inventive, as per "cane toad golf and cane toad cricket, where cane toads are used as balls."

More useful than rats.

Andrew H said...

Ever wondered why anyone would want to keep 30 cats and let them rule their lives. I'd suggest

this and this

Andrew

Jeffrey Davis said...

http://www.youtube.com/watch?v=taLNQWahGbw

Anonymous said...

Breeding hunting out
Of carnivores, no doubt
Like breeding hunting in
To rabbits and their kin

~@:>

Anonymous said...

The article in http://illogicopedia.org/wiki/List_of_things_the_cat_dragged_in
is very deficient in the avian deptartment at least. but it gives some indication of the diet.
They can kill prey the same size at least.

William Connolley said...

More stoats is good, but the NZ folks won't go for that.

Anonymous said...

"Breeding hunting out
Of carnivores, no doubt
Like breeding hunting in
To rabbits and their kin
"

Don Burk once claimed that he could breed a non-hunting cat in five generations, by carefully selection of founder stock. Unsurprisingly his apparently-initiated project quietly disappeared, likely because the only way to breed the hunting imperative from cats is to breed them so that they're effectively mentally retarded.

Somewhat more surprisingly - for a person who has many environmental brownie points - is the fact that Burk was a former director of the astroturf organisation AEC. Although once one pokes around into Burk's political inclinations and personality, perhaps it's not quite so surprising...


Bernard J. Hyphen-Anonymous XVII, Esq.

John said...

Meanwhile, Lake Mead, outside Las Vegas, has a problem with the invasive quagga mussel. The lake is infested by over 320 trillion quaggas, including baby quaggas. If anybody has any bright ideas for dealing with it, let the authorities know.

Anonymous said...

320 trillion!?

"Everything in excess" would seem to be a good motto for Lake Mead -- and Las Vegas.

It would be very ironic if Las Vegas -- which muscled itself into and created a mega-oasis of ostentation and waste (especially of water) in the most inhospitable environment in the US -- were eventually killed by a little mussel.

But maybe feral walruses would work.

~@:>

Jeffrey Davis said...

The quagga mussel? Ah, the irony.

The quagga (horse) figured in the Utopian imagination of Charles Fourier. The idea that the quagga would choke the water supply of our least/most Utopian city is difficult to get a hold of. Funny? Tragic? Inevitable?

(Confession: one branch of my family hailed from the Fourierist settlement in Claremont, Ohio. I suspect, but haven't established, that they were part of the community.)

Hank Roberts said...

Nice diagram, but too small to include the impact of the 4WD vandals. You want to turn a living mountainside into gravel, you gotta use fossil fueled technology.

Russell said...

In a related develoment, Eli <a href='http://reason.com/blog/2012/08/21/brickbat-rabbit-season"> has gone street legal in Eonnecticut</a>

Anonymous said...

Dr. Lumpus Spookytooth, phd.

sounds like when they first tried engineering population controls at Yellowstone.

david lewis said...

The plan for Lake Mead is to jack up the concentration of CO2 in the Earth's atmosphere until the US Southwest experiences a megadrought, suck all the water out through that new drain they put in the bottom, and presto, Lake Mead is dry.

Everyone is going to come down and laugh at those 320 trillion quaggas writhing around on the dry lake bottom. That'll show them for thinking they can take over the lake. It's going to be a hoot.

Brian said...

Bernard - interesting proposal by Burk. But just because he failed or didn't really try, doesn't mean others would fail.

John - my brilliant proposal for the quagga is to wait a few thousand years for nature to solve the problem. Just don't cause any other problems in the meantime.

Russell said...

Plan B is to wait until the quaggas lie steaming in the Dry Gulch Formerly Known As Mead, pour in the European Wine Lake, and let Vegas's All You Can Eat buffet patrons have at them.

Anonymous said...

Coyotes are willing to snack on humans. They like to get you from behind and knock you down. They are timid and stupid if you face and threaten them. How I know: I had a 30 second real-time learning experience. Fortunately I did the right thing to get out of becoming 'dog-meat'.

Snow Bunny

Anonymous said...

Late comment about the food web pictured here... there should be a direct connection drawn between chipmunks and birds. The cheeky little bastards are significant predators of ground-nesting birds,especially nestlings. By preying on rodents, cats can be a benefit to birds.

My cats catch very few birds (hello? adult birds can fly*), and if they do, they get scolded and lose their outdoor priviledges for a few days. They get praise for all the rodents they bring back. All of my cats are neutered of course.

*In midsummer, when there are a lot of fledgling birds, I tend to keep the cats indoors.