Friday, February 25, 2011

The Tussle.

Sometimes interesting behavior is captured by camera traps.  This occurs, in part, because the person placing the camera is able to find a good spot...but more times than not it has to do with plain ol' dumb luck.

It just so happened that back in August, I was able to get a series of pictures of a few male white-tailed deer (Odocoileus virginianus) attempting to assert their dominance over one another in front of my camera.

Dramatis Personae:
The Brute: I had captured pictures of this fella over a month before the incident.  He's easy to identify becuase of the fibromas that cover his body (for more information on deer fibromas, see the bottom of this post).  Although this picture of his face is blurry, you can see the large fibromas on his right cheek and above his right eye, and near the base of his right-front leg (picture 2 below) that identify him as the likely player later on.

The Upstart:  This individual has a smaller rack than The Brute at the time the tussle occurs.

The Onlooker:  An individual that stands by during the infraction.  He's clearly identifiable by the odd shape of his antlers.

So, our little performance begans at roughly 1:21 am on August 25th, 2010 with The Brute.  He appears in front of the camera at about this time.  Note how his antlers have grown since the first photograph of him taken in mid-June.  Whether I am correct in this, or not...I like to imagine he is the "resident male", defending his little patch of territory from intruders.

Before long, something catches his attention, and he turns.

Soon The Onlooker appears, and you can barely see The Upstart behind him.

After several minutes, The Onlooker turns as The Upstart passes him and comes into frame (perhaps being pursued by The Brute).

The confrontation ensues as The Brute appears from the left....

And eventually...The Brute drives off The Upstart.
Although he does give The Onlooker a brief glance, there appears to be no interest and off he goes behind The Upstart.

As great as camera traps are, they survey a very small capturing pictures similar to this are sort of a shot-in-the-dark.  This is especially true if one is not putting out bait to attract the deer, which I am not.  In fact, I'm not even really targetting deer with my cameras.  The purpose is to inventory wildlife on-site..and I know there are deer (TONS of deer) without using a wildlife camera trap to detect them.

According to Webster et al. 2003 (Mammals of the Carolinas, Virginia and Maryland) the rutting/mating season usually occurs in Autumn here.  The North Carolina Wildlife Resources commission reports this would be specifically be in November.  Testosterone levels are reportedly low in the summer.  So, I was alittle surprised to see this type of behavior in late August.  Seems a bit early.

But, it's only an anecdotal observation...and I ain't a deer.


Further Information about Deer Fibromas:

Fibromas are considered a "cutaneous neoplasm" that occurs in members of the deer family (Cervidae).  "Cutaneous" refering to the skin and "neoplasm" being the technical term for a tumor or abnormal growth.  According to Sunberg and Nielsen in 1981, "viral particles" have been found in the nuclei of cells from deer fibromas and they suggest transmission is similar to that of any virus.  Becuase fibromas often become cracked, or ulcerate, which can result in bleeding, un-infected animals may become inoculated if they, themselves, have a scratch that comes into contact with the ulcerated fibroma of another deer.  Also, scratched skin coming into contact with vegetation that has touched the ulcerated fibroma of an infected individual is a possible means of transmission.  Finally, blood-feeding insects may be an important vector.  Although this information is somewhat dated, Sunberg and Nielsen also summarize data on the prevalence of fibromas in white-tail deer populations reported by other studies: 
  • Of 3,000 deer harvested in New York State in 1962, 1.4% had tumors that may have been fibromas
  • Of 236 deer examined from 1946-1958 at the University of Maine, 5.5% had fibromas
  • Of 861 deer examined from 1933-1962 in Michigan, 1.3% had fibromas.
So, a pretty low rate of occurrence.  Also of interest is the fact that, of the deer with fibromas in the New York study, the majority were male.  This would sugget that male-male transmission may occur during tussles in the rutting season, or from the rubbing of antlers to remove velvet on a tree that was previously rubbed by an infected individual.

Because these fibromas are cutaneous (involving only the skin), they are not considered a major health hazard for the deer..of course, unless they become particularly congregated in areas around the nose or eyes (which can lead to secondary mortality, not as a result of pathology related to the fibroma). 

It is also worth noting that, most sources indicate fibromas are not a health hazard to humans, and according to the Michigan Department of Natural Resources and the Environment, are not known to infect humans.  For the most part, they're just unsightly...and may make a infected deer undesirable as a "trophy".

Literature Cited:

Sundberg, J.P., and S.W. Nielsen. 1981.  Deer Fibroma: a review. Canadian Veterinary Journal 22: 385-388.

No comments:

Post a Comment