Dicromantispa interrupta

Dicromantispa interrupta

Thursday, July 3, 2014

Deer, Ticks, and Lyme Disease

Connecticut scientists have published the results of a 13-year monitoring study of what happens to tick numbers and the incidence of Lyme disease when deer populations are reduced in number: tinyurl.com/oaqf65s.

They found that when an area’s deer population was reduced in number by 87%+, as in their case by hunting, the numbers of ticks found on people and cases of Lyme disease dropped 76 and 80%, respectively.

Computer modeling studies indicate that populations of some species can be eliminated over time by reducing the number of fertile individuals below some threshold. In the case of feral cat colonies that are not artificially augmented (e.g., immigration, abandonment), TNR must sterilize ≥ 82% for colony die-out over 11 years. I suspect that similar rates might be appropriate for some other mammals. However, 87% is evidently not too high for deer in Connecticut (and likely not for feral hogs, either).

Nonetheless, these two sets of observations lead to two notions, that (1) we might be able to reduce the incidence of Lyme disease by reducing deer populations through intense hunting pressure and predator restoration, and (2) large predators and the pre-Columbian, contiguous Eastern forest together may have limited deer numbers and consequently kept Lyme disease case numbers down.

Eat mo’ venison!