Did coyotes trigger the ticks-Lyme scourge?
I am always amazed at the interconnectedness of nature. One recently revealed example: it seems the explosive growth in the black-legged tick population and the burgeoning epidemic of Lyme disease is caused by a complex and fascinating series of ecological reactions involving the Eastern coyote.
You can read about the most recent research on the subject, which was published in the June edition of the journal Proceedings of the National Academy of Sciences, in a story in Scientific American online at http://bit.ly/Kwakdo. The study was done at the University of California, Santa Cruz.
But perhaps to really appreciate the chain reaction that apparently has led to the Lyme disease scourge, we must go back a century or so to southern Canada and perhaps northcentral United States, where humans slaughtered so many wolves that the wolf's social pack structure was decimated.
That resulted in – for a short time, perhaps only decades some scientists believe – male Canadian gray wolves mating with female Western coyotes.
The resulting hybrid animal was the Eastern coyote – bigger, grayer and a more efficient predator than the Western coyote. Those animals migrated south and east, and now most coyotes in Pennsylvania and the Northeast are their progeny.
Research done in Massachusetts, New York and most recently Pennsylvania has confirmed that most coyotes carry the wolf genes. As we have seen in the results of organized coyote hunts, some get big; 50-pound males are not uncommon.
As we all know, coyotes are very prevalent in our state and the Northeast. And just like wolves, under normal circumstances, don’t tolerate the presence of coyotes, Eastern coyotes kill foxes. And the assent of the Eastern coyote in the Keystone State and the rest of the Northeast has resulted in the sharp decline in red fox numbers.
Researchers found that where there once was an abundance of red foxes, there is now an abundance of coyotes. That’s significant because the fox’s diet consists of small rodents such as the white-footed mouse, known to be one of the prime hosts of the tick that carries the bacteria that causes Lyme disease.
Coyotes eat rodents, too, but scientists suggest they are more focused on bigger prey.
So the decline in red fox populations may well be responsible for the explosion in tick numbers and Lyme disease in the last decade. When fox numbers dive, scientists tell us, mouse populations climb, and ticks follow suit.
We have been told for years that the increase in ticks and Lyme disease resulted from an overpopulation of white-tailed deer. Now scientists are realizing that may not be true.