The Impact of Trauma on Wildlife Health

Between the spring and fall of 2017 North Atlantic right whales experienced a mass mortality event caused by collisions with vessels and entanglements in fishing gear, resulting in the deaths of 16 whales during this time period. In a single night in May 2017, approximately 400 migratory birds died after colliding with a building in Galveston Texas. While these tragic events garnered a great deal of media attention, trauma is generally underappreciated as a major cause of wildlife mortality.

North Atlantic right whale brought ashore for necropsy during the 2017 mass mortality event. Photo credit: Marine Animal Response Society, 2017.

Trauma is responsible for an enormous number of wildlife injuries and mortalities annually. Estimates suggest the number bird-window collisions in Canada could be as high as 25 million per year, and an additional 14 million birds are killed through vehicle collisions per year. In the year 2000 alone there were over 30000 reports of collisions between mammals and vehicles. Additionally, while road mortalities involving reptiles and amphibians are generally under reported it has been suggested that in some cases these species could comprise more than 94% of such incidents.

Owls and passerines are the most common bird species killed by vehicles in Canada. Young, inexperienced birds are often more likely to be injured or killed by vehicles. Photo Credit: DM Jefferson.

Small, inconspicuous reptiles and amphibians often must cross roads to travel among habitats making them highly vulnerable to road mortality. Photo Credit: SE Fisher.

In preparation for the upcoming 2017-2018 CWHC Annual Report we have conducted a database search of trauma incidents over the five year period from 2013 through 2017. The results of this search produced a total of 7364 incidents involving 3043 (41%) birds, 4215 (57%) mammals, and 106 (1%) other species (Fig.1 and Fig. 2). Collisions with vehicles represent the majority of trauma incidents with a total of 3977 (54%), while collisions with structures comprised an additional 742 (10%) incidents; combined these two forms of collision were responsible for 4719 (64%) trauma incidents. Human inflicted trauma (excluding vehicular collisions) were found to be responsible for approximately 540 (7%) incidents; misadventure was responsible for approximately 140 (2%) incidents; predation was the cause of approximately 447 (6%) incidents; and 1518 (20%) incidents resulted from some trauma that could not be specified (Fig. 3). *See footnote for definitions of trauma categories.

Fig. 1: Number of incidents in each category of trauma reported for each of the animal categories.

Fig. 2: Percentage of trauma incidents involving each category of animal.

Fig. 3: The percentage that each category of trauma contributed to the overall surveyed incidents.

Reports and submissions from the public are vital to the success of the CWHC-RCSF’s wildlife health surveillance. If you observe any incidents of sick, dead, or injured wildlife please report them to your nearest Canadian Wildlife Health Cooperative regional centre.

For some additional information on trauma you can check out our infographics on Reducing Bird-Window-Collisions; Reducing Wildlife-Vehicle Collisions; and the collaboratively produced Incident Report on The North Atlantic Right Whale Mortality Event. Additionally, if you are in PEI or NL and you can report bat encounters through our Toll-Free Bat Number.

*Trauma Categories Defined

Human Inflicted (non-vehicular): trauma resulting from any human interaction other than vehicle collisions (e.g. hunting, trapping, angling, malice, accidental injuries/deaths from handling/capture/research/rehabilitation efforts, etc.).

Vehicular Collision: trauma resulting from collision with any form of vehicle (e.g. car, trucks, trains, air craft, ships/boats, motorcycles, bicycles, farm equipment, etc.)

Structural Collision: trauma resulting from collision/entanglement with a structure (e.g. houses/buildings, fences, barbed wire, electrical lines, lamp posts, signs, wind turbines, etc.).

Predation: trauma caused by an attack from a non-human predator (e.g. cats, dogs, wolves, foxes, raptors, etc.).

Misadventure: naturally occurring, accidental trauma not involving humans (e.g. weather related injuries [e.g. lightning strikes, hypothermia, etc.], trips/falls, fighting among individuals).

Unspecified: source of traumatic injury/death could not be inferred from the data provided.