Sunday, March 30, 2014

No luck in Louisiana

Wildlife biologists can be an awful lot like gold miners, exploring new areas to be the first on the scene to find a new species or rediscover an ancient overlooked vein of biodiversity.  But sometimes what you don't find is just as important as when you uncover that rare nugget.  This is certainly the case in survey efforts to find eastern spotted skunks, a species on a precipitous decline across much of its range.  

Over the course of four years between 2009 and 2012, researchers Paul Leberg and Rebecca Davis of the University of Louisiana at Lafayette used proven spotted skunk detection methods to try to find out if eastern spotted skunks still remained in the Louisiana.  Using a combination of baited track plates, remotely triggered camera traps, hair snares and live traps the researchers failed to find even a single trace of an eastern spotted skunk remaining in the state.  

Declines in eastern spotted skunks across their historic range have been reported to be as high as 99%.  In Louisiana, a 97% decline in eastern spotted skunks was first documented over four decades ago based on declines in statewide fur sales between the 1920's and 1960's.  Now there is scientific evidence to suggest that eastern spotted skunks are very rare or perhaps extirpated from the state.  

The author's failure to find even a single animal following the first systematic survey of a state at the core of their former historic range should raise further conservation concern for the future of this species.  Unfortunately, with spotted skinks being so rare and on the verge of extirpation in Louisiana and elsewhere through the central, southern and eastern US, it is increasingly difficult or impossible to learn what they need to persist.  

We now more than ever need the public to step forward with sighting of this species so that researchers can begin to conduct detailed studies to find out about there ecology.  Only by discovering what conditions they do rely on and what impacts their survival will we be able to conserve the species effectively into the future. 

Further reading:

Gompper, M. E. and H. M. Hackett. 2005.  The long-term, range-wide decline of a once common carnivore: the eastern spotted skunk (Spilogale putorius). Anim. Conserv., 8:195-201.

Leberg, P. and R. Davis.  2013.  Assessment of population status and habitat use of the eastern spotted skunk in Louisiana.  Final Report submitted to U.S. Fish and Wildlife Service, Lafayette, Louisiana.

Lowery, G. H. 1976. The mammals of Louisiana and its adjacent waters. Kingsport Press Inc. Kingsport, Tennessee.

Sunday, March 2, 2014

Don't mess with the spotted skunk!

Video footage from California suggests that when it comes to scavenging a deer carcass, the diminutive western spotted skunk gets first dibs.  Scientists at University of California Davis placed a trail camera on deer that was killed by a mountain lion they had been studying (note the tracking collar in the video below) when they happened to catch on video a western spotted skunk chasing a much larger mountain lion from the carcass.  

The observation was reported in the recent issue of Canadian Field Naturalist where the authors note that despite the spotted skunk being 1% of the body size of a mountain lion, it not only chased the big cat off of the carcass once, but again when the lion returned.  This represents the largest reported size differential of a smaller mammal successfully out-competing a larger one.  Way to go spotted skunk!

While cougars are not present in our study area here in the Appalachian mountains, this video footage makes us wonder about how we interpret interactions like the one in the image below.

Is this an example of multiple carnivores "sharing" a carcass, or could the camera trap image only be capturing the moment right before aggression?