About Me

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Native Californian, biologist, wildlife conservation consultant, retired Smithsonian scientist, father of two daughters, grandfather of 4 small primates. INTJ. Believes nature is infinitely more interesting than shopping malls. Born 100 years too late.

Saturday, May 19, 2007

A ratty flashback

Ever since discovering the screech owl nest I've been scouting for nest cavities of other owls.

I'm about to give up. With the exception of the fortuitous encounter with the saw-whet owl, none of the tree cavities I've staked out during the past 2 weeks have yielded anything but deer mice and wood rats.

These pictures were from the most active site. A gopher snake was resting quietly at the base of the tree when I arrived. As it parted ways it occurred to me that I might be wasting my time. The snake might have eaten the occupants, but then again, maybe the snake would come back and eat the occupants after I left. Now, that would make a story.

Three days later there were 44 exposures; 14 were of deer mice, and 9 were of a wood rat. The rat and mouse visitations were separated by a couple hours.

The wood rat must have found the quarters a little cramped.

Nonetheless woodrats and deer mice cohabitate in the rats' stick nests. In fact, the coastal subspecies of the California mouse (Peromyscus californicus) was dubbed "parasiticus" because of its habit of living in nests of the dusky-footed wood rat.

The Allegheny woodrat, on the other hand, may not be as mouse-tolerant. If you'll excuse a flashback, I'll explain.

Many years ago a senior colleague of mine at the National Zoo had an uninvited dinner guest in the form of an Allegheny woodrat. This was shortly after Guy had moved into a partially renovated cottage at the zoo's Conservation & Research Center. Aware that the rodent was the previous occupant, and perhaps with a twinge of guilt, Guy offered it some hamburger from his plate.

Guy related the story in my office the next morning. After going to bed that night the rat had lived up to its moniker of "trade rat". It had deposited several pieces of plaster on the floor near the dinner table. (There was apparently a large supply of the relics of the lath and plaster walls under the house.)

Might the rodent become a nuisance? I asked. He didn't think so. The completion of the dry-walls would create a rat-proof boundary.

The dry walls were completed a few days later, but the rat kept showing up at dinnertime and continued delivering its nightly gift. Guy's amusement quickly wore off. I knew the game was over when he came puffing into my office one morning and deposited a bag of broken plaster on my desk. He explained that this vast amount--enough to fill a 2 lb coffee can--was deposited just last night.

It was time to catch the rat.

I live-trapped the rodent, and put it in a large cage of 1/2" hardware cloth in my chicken coop. In due course it made a respectable nest out of shredded feed bags and -- you won't believe it -- its own fecal pellets, which it heaped on top of the nest box.

The rat was particularly fond of animal protein. It tackled chunks of ham fat with the ferocity of a predator, literally throwing itself against the mesh, pulling the scraps through the mesh, and dragging them into its "lair".

Curiously, no mouse was permitted to share its domain. It promptly dispatched trespassing mice, and incorporated the carcasses into the pellet pile, which became a grotesque collection of fly-blown mouse mummies.

The rat thrived for 6 months, and then one night I left the cage open, thinking it might return for a day or two to the familiarity of its old digs.

Apparently it never looked back..

Such are the flashbacks after a bad day on the camera trapline.