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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.

Monday, May 21, 2007

A victim of Nackenbiss

Check out the skunk's neck. Yes, yes, yes -- that's a mouse in its mouth (and a trespasser from my garage where no mouse is tolerated.) But that's not the point. I want you to look at the skunk's neck. Can you see that the wounds are on both sides of the neck?

Sooner or later those who live close to nature encounter the diseased and injured, and it sinks in that "nature is red in tooth and claw".

So how did this happen? I offer four scenarios based on the observation that the wounds look traumatic, rather than the result of irritation.

Scenario 1: The skunk got its neck caught in some chicken wire, and scratched itself trying to get out.
This is possible, but I don't think it is likely. No one in the neighborhood keeps chickens or keeps chicken-wire cages, and the chicken-wire under our deck has already been breeched and offers free and safe access to critters seeking shelter.

Scenario 2: The skunk suffered from a neck bite during a sexual tryst.
If we knew this to be a female skunk, and it was earlier in the year -- like January or February -- a romantic interlude would be quite possible. The courthip of mustelids (members of the weasel family) is well known for prolonged bouts of neck biting along with all the other stuff. But the breeding season is past, and little skunks should be appearing soon; so I don't think it is very likely. I might also add that I haven't seen wounds like this in skunks photographed earlier in the year when "love is in the air".

Scenario 3: The skunk suffered from a predatory encounter with a naive bobcat or coyote.
Many mammalian predators, especially cats and weasels, dispatch their prey with a neck bite which severs the spine. Note that this skunk shows wounds not only on its neck. There are also scratches on its head.

In this case the hypothetical predator might have lost its appetite when overpowered by skunk musk. This scenario is feasible. A naive predator might try to nail a skunk once, but the skunk's chemical defense and uniquely bicolored coat are highly effective teaching tools. Smart predators learn their lesson from a single experience. (Domestic dogs seem to require several trials, and some never seem to get it.)

Scenario 4: The skunk had a brawl with another skunk.
This would be more likely in male than female skunks. Carnivores tend to fight over food and sex. Since skunks don't have to defend their food (which comes in small packets), I suspect that studly skunks fight over females. Whether male skunks fight by attacking each other's necks, I just don't know. It seems possible, but perhaps a mammalogist out there can enlighten us.

We haven't solved the problem, but my guess is that the luckless skunk was attacked by a coyote, bobcat, or fox. By discharging its scent gland, it not only saved its own damaged neck, but taught one more predator that 'ole stripey' isn't to be trifled with. In other words, his own close calls and occasional misfortune benefits other members of his species.

[By the way, German-speaking ethologists identified the Nackenbiss (=neck bite) as a fixed action pattern. It is innate (=genetically programmed), typical of the species, and is tiggered by specific sign stimuli. It is used in predatory, sexual, and maternal situations with very different effects.]


brian miller said...

I would vote for scenario 3 or 4. When black-footed ferrets (another mustelid) fought, or play-fought, most of the bites were aimed at the neck. At 6 weeks of age, 65% of play-bites were aimed at the neck. By 12 weeks of age 90% of play-bites were nackenbiss. That seems to be a critical period. Neck bites make grip retention stronger, and it is harder to receive a retaliatory bite.

Camera Trap Codger said...

Thanks Brian -- I was hoping some mustelid enthusiasts would speak up. I've seen similar behavior in African civets and genets. Apparently a number of carnivores bite the neck during fights and threats, and some species have developed thickened skin there, a dermal shield so to speak.

Castellanosm said...

The blog is always fascinating Chris. We on the right coast really enjoy your work. Would you be interested in helping me set up a similar outfit for Rock Creek (NZP)?


Camera Trap Codger said...

I'd be happy to help, Mario. You've got a perfect setting there at Rock Creek Park, and it would be a fun project. Camera traps will give you a good idea of what's prowling around the zoo at night. Give a call or send me an e-mail.

Mary Cummins - Animal Advocates said...

I've gotten in skunks with scars like that. Sometimes it's from digging for grubs in the grass. If it's sod, they get the nylon netting stuck around their neck. Here's a photo of such a skunk. They are naturally curious and will stick their head in everything from yogurt tubs to peanut butter jars.

Mary Cummins
Animal Advocates