What killed this White-tailed Deer? Part 6: Results and Discussion

I want to start by reviewing the evidence that we observed before I offer some conclusions.

§         We discovered the animal dead within 50 feet of Bissell Rd.
§         There were some external injuries to the hind limbs and although the animal was still warm the crows were already starting to eat portions of the carcass.
§         We determined that the animal was an adult female approximately 6 years of age.
§         The carcass did not exhibit any internal injuries, or at least none were observed. 
§         The kidney fat index and heart fat index were low but small amounts of fat were observed.
§         The bone marrow fat index was marginal. 

I started this examination thinking that there could have been several factors that contributed to the death of this animal.  I hypothesized that it could have been struck by a vehicle, predation, or winter severity.  I feel confident to conclude that it was not struck by a vehicle.  The internal organs were not injured nor were any of the large bones.  This gave you an opportunity to examine relatively healthy white-tailed deer internal organs.  Pretty cool, Huh! 

I was left wondering if this winter was severe enough that the animal depleted its fat reserves and could not procure enough food due to the deep snow.  This doe was an older animal with respect to the rest of Connecticut’s white-tailed deer population.  Old and young animals tend to die during seasons of extreme environmental stress.  All Connecticut residents can attest to severity of this winter.  We had extremely deep snow, cold temperatures, and with relatively no thaw like we usually experience during most winters. 

I also wonder if predators could have wounded the animal enough that the animal died from these injuries.  Coyotes are quite common on the property and are observed eating from deer carcasses.  They quite often employ a strategy of wounding an animal's hind limbs and then letting the animal wander off to die.  This strategy is quite efficient because they do not have to expend more energy to kill a large animal and it reduces their overall risk of being injured by a swift kick from a large animal.  Coyotes are commonly observed scavenging carcasses, which could be an efficient strategy relative to predating their food. 

But why could it not have been a little bit of both factors (winter severity and predation)?  Unfortunately, we can’t say that one factor was the only thing that killed this animal.  So, we have to hedge our bets and say that both factors contributed to this animal’s death.  The animal died at the end of a severe winter and Eastern coyotes are known to predate white-tailed deer when the deer’s movements are limited and they are in a weakened condition. 

We need to be very cautious to not expand this observation to what happens to all white-tailed deer that died this winter.  It only indicates what may have happened throughout the state.  White-tailed deer were observed exhibiting “yarding” behavior throughout the state of CT.  “Yarding” is a seasonal migration pattern usually observed in white-tailed deer populations in Northern New England, Adirondacks of NY, some of the Northern Midwest States and Canada Provinces.  White-tailed deer migrate long distances from their breeding/warm season grounds to a central location that provides several resources that they need to survive.  These locations offer adequate cover, food, water, and space so that they can survive the extreme winter environment; in other words these are their winter “habitats”. 

I hope you enjoyed this series.  It was an unique opportunity to show you not only what a white-tailed deer looks like from the inside and out, but also it gave me an opportunity to demonstrate one activity performed by a Wildlife Biologist.  You have learned what knowledge we have as a discipline by those who created that knowledge before us.  You also have learned how we apply this information to monitor and learn more about the populations we conserve.  I hope to show you more things like this in the future.  So, come back soon and often. 

No comments: