Precocious Devils Fight for Their Lives
It’s a turbulent time for the sex lives of wildlife Down Under. The other week, I blogged about New Zealand’s tuataras, ancient reptiles imperiled because warming temperatures may cause all of their offspring to be born male. But while boy tuataras could soon face imbalanced sex ratios and a prolonged bachelorhood, nearby, Tasmanian devils are coupling at younger ages these days, according to a new study in the Proceedings of the National Academy of Science. Females are now more likely to start breeding at the adolescent age of one, instead of a more normal two or three.
The reason isn’t that young devils these days are extra promiscuous--for them it’s a matter of life or death. The phenomenon is an interesting, albeit upsetting, example of evolution in action. Their earlier couplings may be a rapid adaptation to the devils’ shortened lifespan during the last decade.
Declared an endangered species this past May, populations are being decimated by Devil Facial Tumor Disease, a deadly cancer which was first documented in 1996. Since then, the average number of devil sightings has dropped by about two-thirds, with declines up to 95% at the epicenter in northeast Tasmania. The mysterious disease is only one of three known cancers in the world that spreads infectiously--in this case, probably when one animal bites another.
This is reportedly the first time that scientists have observed a species breeding younger in response to a contagious disease. The rapidly-progressing cancer is 100 percent fatal and, in areas where it’s present, affects nearly all individuals by the time they are two or three (their normal lifespan is five to six). The precocious breeding response gives female devils a chance to have one litter, though they often don’t live to raise these offspring. Researchers think that early breeding may help prolong the lifeline of the species, but are not hopeful that this evolutionary strategy will be enough without some help.
Saving these screeching, malodorous marsupials seems to becoming something of a cause, even as far away as here in the States. The first time I heard about the plight of the devils was last year, randomly during a presentation before a taxidermy contest I attended in Brooklyn, NY (albeit only as a spectator). Though I didn’t know much, the photos I saw were pretty disturbing, and I added to the collection pot that was passed around. I hope my money went to the Tasmanian government’s Save the Tasmanian Devil campaign, which judging from their web site seems pretty extensive. They're using a mix of lab and population studies, and wild and captive management strategies, including “Project Ark,” in which they hope to increase the healthy, captive population size as a sort-of insurance policy in case wild devils go extinct. They are also hoping that Cedric, a lone devil that has proved so-far immune to the tumors, may hold the genetic key to a vaccine.
This is a good time to remember the cascade effect that top carnivores have on their surroundings. Though the devil, known for its nocturnal howl and Looney Tunes namesake, is a national symbol in Tasmania, its value to the ecosystem is more than sentimental. The largest of marsupial meat-eaters, devils actually forage for carcasses more often than they prey. The government web site reports that they are already noticing that surplus carrion is aiding the expansion of introduced and invasive species, such as feral cats, dogs and wild foxes. If foxes fully establish themselves, they would prey on an estimated 70 vertebrate species and directly endanger seven.
In short, humans need the Tasmanian devil, probably as much as they need our help right now.