Red fox populations in North American are rapidly decreasing and researches think they now know why – Lyme disease. The number of Lyme disease cases have risen dramatically since 1997, according to MSNBC. The influx of Lyme disease cases which have risen by as much as 380 percent in some states, has occurred independent of deer population fluctuations. Coyotes taking over the traditional red fox ranges in multiple states may play an integral role in the plummeting red fox population.
Deer are are well known carriers of the bacteria which causes Lyme disease, but researchers do not feel the problems with the red fox is related to an over abundance of deer. The disease is spread by ticks which contract the bacteria from infected rodents and deer. When a human is bitten by an infected animal they become ill as well. If a Lyme disease carrying tick is detected early, the human can be treated with antibiotics to kill the potentially deadly bacteria.
The Proceedings of the National Academy of Sciences journal excerpts republished on Live Science note a “wide decline” of “key small-mammal” predators due to increases in the coyote population. The coyote population has grown while red fox numbers have dropped in the same regions. Researchers have also found that due at least in part to the decreasing red fox population during the past three decades, small rodents which are typically eaten by the fox have increased substantially.
University of California graduate students studying the red fox problem reviewed data from five states and charted the spread of Lyme disease. The statistical model created by the students determined that as the red fox population dwindled, reports of Lyme disease infections increased without any change to the local deer population.