| Many causes of traumatic injury are encountered in wildlife
forensics. This portion of the website deals with injuries other than those caused
by firearms, such as vehicle collisions, electrocution, sharp instruments, bludgeoning,
and various trapping techniques. We will review some of the typical findings with
different causes. Please remember that cases may not be as straightforward as
depicted here. |
| Vehicle Collisions |
As roads encroach into almost every corner of the North America,
it is not surprising that wildlife frequently fall victim to vehicle collisions.
What is the significance of vehicle collision to wildlife forensics? After all, it
might be difficult to prove that someone intentionally ran down an animal (although -
people have been prosecuted for hitting deer with cars for food!). These cases may
be presented to determine cause of death when other causes are suspected.
For
example, animals are frequently shot from vehicles along roadways. Animals
debilitated by toxins may die by the road as well. Also, as power lines frequently
run along roads, electrocution would be another consideration for avian species.
The
necropsy findings with vehicle collisions are fairly predictable. On external
examination, abrasions and hair loss may be evident from contact with the road surface
(a.k.a. road rash). Victims usually have significant internal bleeding. Fractures
may occur, but are not necessarily present. Let us look at two vehicle collision
cases. |
This is a coyote (below) that was run down by a snowmobile (you were
expecting a car?). The hide was removed to help find areas of trauma. You can
see a large area of subcutaneous hemorrhage over the dorsum (red circle). This
animal also had severe internal bleeding. An investigator cannot definitively state
what inflicted this wound; however, his/her observations may support other evidence
gathered by investigators.
This incident occurred in Western Canada where this crime
is a problem. Snowmobile riders find coyotes out in large snow fields where there is
no cover to escape. The next example occurs all too commonly in the
Southeastern U.S. |
|
 |
Boat collisions are a major cause of mortality in Florida
manatees. You can see the lacerations left by propeller blades on this animal. |
|
| As automobile collisions most often produce injury by blunt
trauma, we will take a brief moment to discuss similar injuries caused by other
means. Blunt trauma from instruments, such as bludgeoning, produces focal traumatic
lesions , i.e. hemorrhage, fractures. Depending on the object used, the lesions may
be too nonspecific to identify a specific type of weapon. However, instruments such
hammers and axes can leave distinctive wounds. |
| Electrocution |
Electrocution in wildlife forensics most commonly involves power
lines and avian species. As stated under vehicle collisions, power lines often run
parallel to roadways, thus the two causes of death must be differentiated.
Power
companies may be subject to fines or equipment alterations based on cases of
electrocution. Unfortunately, power poles and lines are a common place for birds,
especially raptors, to light, hunt, and even nest. Birds are exposed in these
locations and easily can be shot from their perches. Thus, gunshot is another
rule-out in these cases. |
The mechanism of death in cases of electrocution is ventricular
fibrillation. Intercostal spasm and subsequent respiratory arrest also may be
involved. Terminal hemorrhage at the base of the heart (reported in eagles) and
muscle trauma may be observed due to violent contraction or subsequent falls (Stroud
1996).
Grossly, burns may or may not be present. Focal burns are accompanied
by singeing and curling of feathers. As these birds may fall from great heights,
secondary trauma also may be present. |
| Cutting Injuries |
Injuries caused by sharp-edged instruments are most commonly
encountered when animals are incised along the neck as part of the field dressing
procedure or to inflict a final fatal wound. Incision injuries also are produced
when body parts are removed to harvest specific portions or to conceal an animal's species
or sex.
First, an investigator must determine whether an injury was inflicted while
the animal was still alive or post-mortem. This information can be determined by
examining the wound edges. In a living animal, the wound margins are infused with
blood. In contrast, infusion does not occur following death. There is other
valuable information that investigators can gather by looking at incision wounds.
Let us look at some examples. |
 |
Here is a relatively common
scenario. Some hunters were found in possession of 3 freshly killed decapitated
carcasses. The head, viscera, and genitals had been removed. At a nearby farm,
three heads were found. The hunters were suspected of trespassing to hunt without
permission and for taking two does on a male-only harvest day. |
 |
You can see here that the forensic
pathologist was able piece together an impressive display for the prosecution.
Good
apposition can be a helpful characteristic of incision wounds. However, the investigator
did not stop there. |
 |
When cervids are decapitated either as
part of the normal field dressing procedure or to collect a trophy, the cervical vertebrae
often must be cut with a saw or some other cutting instrument. |
| In this case, the cut
did not extend cleanly through the articulation. Fragments that were broken off of
the cervical segment attached to the head were still attached to those segments left with
the body. The pathologist carefully boiled the segments down to harvest the
bones. |
 |
Here is the result. A fragment
from the body clearly matches the vertebral body from the head portion. Convincing,
is it not?
If the match was not so clean, can you think of another method that we
could have used? |
| DNA analysis of course! Forensic laboratories equipped to
handle wildlife cases have PCR primers for many common species. We could have
matched the DNA from the head and body specimens. |
|
| Matching lines of incision also works well on the portion of the
carcass referred to as the cape (skin covering the neck and head). Hunters remove
the cape for taxidermy purposes. Often, cartilage left in the nasal region of the
carcass can be matched with segments adhered to the cape. |
| Trap-related Injuries |
Trapping fur-bearing mammals is a legal means of wildlife harvest,
provided that trappers abide by trap design regulations and take animals during the
appropriate hunting season.
We will discuss two general types of traps, the
clamp-style traps and the snare-type mechanism. Clamp-style traps operate on a
spring mechanism, whereby the jaws close in the animal. Most people are familiar
with leghold traps.
Another type, called conibear trap, is designed to grasp animals
around the body rather that an appendage. Many designs and styles exist for both
types of traps. As the name implies, snares operate by creating a locking noose. |
 |
This coyote was caught in a leghold type trap. Lesions
caused by these devices can be extremely subtle, such as in this case.
You can see
the severe edema in the distal limb. Also, there appears to be an abrasion proximal
to the carpus. |
| On external examination, such lesions may not be evident and removal
of the skin is necessary to visualize abnormalities. On the other hand, some leghold
trap lesions may be quite gruesome, resulting in open fractures and self-mutilation. |
 |
Here is another coyote. This animal appeared to have died
by gunshot. |
 |
After skinning the animal, this ligature mark was identified
around the caudal abdomen.
It was suspected that the animal was snared before being
shot. |
| Again, this case demonstrates the importance of skinning the animal during a
forensic necropsy. Are you detecting a recurrent theme here yet? |
|
| Toxicology >> |
|
^ Top
of page |
Veterinary Forensic Pathology | Traumatic Injury 