Monday, May 9, 2016

Ticks, Deer and Fire

Tick infested fawn - Sam Leatherman
Ticks can be a major annoyance and transmit disease but I had never considered them a significant cause of wildlife mortality.  An article from the Quality Deer Management Association (QDMA) documents how serious a problem this can be.  "According to The Field Manual of Wildlife Diseases in the Southeastern United States, a comprehensive guide published by SCWDS, "heavy infestations of [ticks] may produce fawn mortality up to a reported estimate of 30 percent.”  Wildlife biologist Brian Towe reports:
"In 2012, I encountered 33 fawns that had become blinded in both eyes due to the onset of infection from the high volume of ticks surrounding the eye socket. Unfortunately those fawns were euthanized after efforts to improve their condition failed. While 33 isn’t a large number over a broad landscape, that number came from a single Missouri county, a scenario that played out through many other counties of Southern Missouri that year. One fawn that I and a wildlife rehabilitator worked to save had 316 ticks removed from the right eye and 257 from the left! So, while most deer managers highlight the impacts of hemorrhagic disease during 2012, I also reflect on the impact ticks had on our future standing crop."
In the early 20th century many Ozarkers burned their fields to get rid of ticks.  Does that work?  Another article in  QDMA says yes, for a year.  Several sources cited say that the next year the tick population rebounded, sometimes to a higher level.

Research conducted in the Missouri Ozarks by Brian F. Allen was published in 2009, showing that same decrease and rebound pattern.  The lone star tick (Amblyomma americanum) larva density was the greatest 2 years after a burn, six times higher than in adjacent unburned areas.  Deer density was also greater as they moved in to feast in the newly emerging grasses, a trick well known to the Osage in the presettlement period.  Unfortunately the deer bring in their ticks which find a new home.

Now here is where it gets really weird.  Research by the same Brian F. Allen showed that deer are attracted to areas dense with invasive bush honeysuckle (Lonicera maackii), increasing the number of lone star ticks which transmit ehrlichiosis to humans.  Experimental removal of bush honeysuckle caused a reduction in deer population and infected tick numbers.  It also reduced the number of blood meals away from deer.
Attacking invasive bush honeysuckle is a win-win!  More on bush honeysuckle and ticks is on this previous blog.

No comments:

Post a Comment