Researchers find increase in Lyme disease mirrors drop in red fox numbers

http://news.ucsc.edu/2012/06/red-fox-lyme-disease.html

June 18, 2012
By Guy Lasnier

A continued increase of Lyme disease in the United States, once linked to a recovering deer population, may instead be explained by a decline of the red fox, UC Santa Cruz researchers suggest in a new study.

The team's findings, published in the Proceedings of the National Academy of Sciences, reveal that although deer populations have stabilized, Lyme disease has increased across the northeastern and midwestern United States over the past three decades. The increase
coincides with shrinking populations of the red fox, which feeds on small mammals, such as white-footed mice, short-tailed shrews, and Eastern chipmunks, all of which transmit Lyme disease bacteria to ticks.

Dwindling numbers of red foxes, the authors suggest, might be attributed to growing populations of coyotes, now top predators in some eastern regions where wolves and mountain lions are extinct.

"A new top predator has entered the northeast and has strong impact on the ecosystem," said Taal Levi, a recent UCSC Ph.D. graduate in environmental studies. Levi is the lead author of Deer, Predators, and the Emergence of Lyme Disease, published this week online. Coyotes can and will kill foxes and more significantly, Levi said, "foxes often don't build dens when coyotes are around."

More significantly is that fewer coyotes will inhabit an area once populated by more foxes, Levi said. The greater number of foxes would have consumed a larger number of small, tick-bearing animals than the coyotes that replace them.

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