Causes of Morbidity and Mortality of Wildlife Species Presented to a Wildlife Clinic in East Tennessee , USA , 2000 – 2011

To determine the causes of wildlife morbidity and mortality in East Tennessee, we performed a retrospective analysis using 14,303 records from cases presented to the wildlife clinic of the University of Tennessee between 2000 and 2011. The cases were first categorized into herptile (includes reptiles and amphibians), mammal, or avian and then classified into 1 of 20 groups based on the primary admitting/presenting sign. The top reasons for presentation were trauma, found abandoned/orphaned, hit by automobile, cat-related injury, and dog-related injury. Overall mortality was 45.3% for the herptile cases, 57.6% for mammal cases, and 65.1% for avian cases. There are a variety of reasons animals were presented to the clinic, and some appear to be attributed to anthropogenic factors such as automobiles (n = 1253) and habitat destruction (n = 218), while the origin of others, such as trauma and disease remain unknown. This study confirms the importance of monitoring wildlife morbidity and mortality as an indicator of ecosystem health and of focusing efforts to reduce the anthropogenic threat on native habitats and resident wildlife populations.

Around the world, wildlife species and the ecosystems they inhabit are evolving and shifting in an attempt to adapt to human influences and environmental change.The factors dictating these changes are diverse and numerous, making it difficult to separate the effect each has on species survivorship.Increased morbidity and mortality of wildlife can be attributed to a variety of factors, including infectious diseases and environmental toxins, as well as exposure to such human activities as land development, predation by domestic pets, and automobile traffic [1][2][3][4][5].
As the urbanization of areas with native wildlife continues to increase, numerous pressures are exerted on the natural structures of those habitats.For example, infringing development may not only increase exposure between wildlife species, domestic animals, and invasive species, but may also increase wildlife's exposure to novel pathogens, leading to what Daszak et al. call "pathogen pollution" (2000).Furthermore, fragmentation of natural landscapes and, thus, wildlife populations poses additional dangers.Dividing wildlife species into smaller subpopulations threatens the conservation of biodiversity by limiting the genetic variation within breeding groups and decreasing breeding ground area [6,7].Native habitats are becoming more divided and isolated by land development [3,7,8], and it is possible that this fragmentation may lead to an increase in wildlife morbidity and mortality due to new infectious diseases.Although some of this increased morbidity and mortality can be directly attributed to habitat disruption, it may also be indirectly linked to anthropogenic-induced climate change resulting in the shift of geographic ranges of certain parasites and predators [9,10].Non-native species carry with them non-native pathogens as well as the ability to alter the balance of predator/prey populations in established ecosystems.This introduction of new disease and new predators can have deleterious effects on wildlife species.
Clearing and isolating wildlife habitats may also lead to high-traffic roadways, which increase roadside automobile-related mortalities, noise, environmental pollution, and disturbance stress on the surrounding wildlife [11].The construction of other infrastructure can change the flow of water runoff thereby increasing flooding and further deteriorating the habitable environment.The establishment of neighborhoods and housing communities will likely also increase the number of domestic animals in the area, which provides an unnatural predator stress on nearby native species.
Regardless of whether these increasing threats to wildlife originate directly or indirectly from anthropogenic effects, or as a result of disease spread, it is important to understand the extent of their impact.One study found that trauma and infection were the If cases contained more than one primary A/PS, they were categorized according to the most detailed sign in the description.In cases where multiple signs of equal detail were provided, the case was categorized according to the sign first mentioned.Most of these A/PSs are self-evident; others were grouped as follows: If case notes indicated that there was impaired motor function, a wound or wound abscess, air sac rupture (in the case of 1 songbird), mention of the animal being found entrapped in barbed wire, trap etc., or cases of drowning were all categorized as trauma.Cat related, dog related, and automobile related cases were separated out from trauma in order to show their frequency.Any time "hit by car" was indicated, the animal was placed in the hit by automobile category.If the animal was found "in" the road, it was categorized as hit by automobile, but those that were found "near road" were placed under found/abandoned/orphaned.If a non-specific "dog/cat" or "cat/dog" attack was noted, the patient was categorized by the animal mentioned first.Behaviorally abnormal cases included those that mentioned lethargy, anorexia, aggressive behavior, Journal of Veterinary Science & Animal Husbandry unresponsiveness, weakness, or general statements of acting abnormally.Habitat destruction included nest destruction and any mention of trees being cut down, but cases in which nests fell or were blown from a tree and cases in which a tree fell (but not from being cut down) were categorized as simple found/abandoned/orphaned cases.The category "Disease suspected" includes cases of bloating, scale/feather sloughing, diarrhea, vomiting, infection, fever, as well as any mention of suspected disease, whereas cases without specifics about illness were categorized as sickly/ill.A general description of discharge, missing feathers, and inability to urinate or defecate were all categorized as unknown.
The number of cases in each category was evaluated, and the top four A/PSs were recorded for herptile and avian groups, and the top five A/PSs were recorded for mammals.A drop-off in case frequency after these top categories occurred and there was a high frequency of automobile related cases appearing in all three animal groups.Outcomes (alive, dead on arrival [DOA], died, or euthanized) were recorded for these top A/PSs, mortality rates were calculated for the top four species affected in the three groups, and case fatality rates were calculated for each A/PS.Finally, cases were sorted by year of presentation in order to determine the presence of any temporal pattern.
For the 20 A/PSs, the case frequencies ranged from 0 to 4,492 for each animal group, and the case fatality rates ranged from 0.0 to 1.0 (Table 1).The top four or five A/PSs for the herptile, mammal, and avian groups were determined, and the percentages of cases for each are shown in Table 2.The species most commonly presented and their outcomes are shown in Table 3. Specifically, chelonians with trauma were the most numerous of the herptile cases resulting in death (169 cases), however an additional 163 herptile cases specified death due to being hit by an automobile.Rabbits with cat-related trauma were the most numerous of the mammal cases resulting in death (537), and songbirds with trauma of unknown origin were the most numerous of the avian cases resulting in death (2332).Most common herptiles include chelonia, snakes, amphibians, lizards; most common mammals include rabbits, squirrels, opossums, racoons; most common avian include songbirds, coulumbiformes, raptors, waterfowl * Trauma includes all other types of trauma (ex: blunt force, entrapment, unknown origin) excluding specifically "Cat Related", "Dog Related", and "Hit by Car" ** n is the total number of cases in each species group and admitting/presenting signs, (%) represents the percent of total cases within each species group Table 2: Case outcomes and case fatality rates (CFR) of the most frequent admitting/presenting signs for herptile, mammal, and avian species presented to a wildlife clinic in East Tennessee between [2000][2001][2002][2003][2004][2005][2006][2007][2008][2009][2010][2011] Overall mortality was 45.3% for the herptile cases, 57.6% for mammal cases, and 65.1% for avian cases.Many of the A/PSs could be directly attributed to anthropogenic reasons and accounted for 4,328 cases (30.3%).Reason for case presentation related to habitat disturbance and interactions with humans and domestic pets, in decreasing order, include cat-related, hit by automobile, dog-related, habitat/nest destruction, accidental ingestion (which includes foreign bodies and accidental ingestion of potential poisons), and translocation (Table 1).

Discussion
Wildlife species are continually being presented to veterinary clinics throughout the United States, and it is important to study the reasons in order to monitor the changing health status of the surrounding ecosystem [13], decrease the anthropogenic effect of habitat fragmentation and pathogen pollution [1,3,7,8], and investigate preemptive strategies for reducing the number of wildlife casualties.This large dataset provides a good sample to thoroughly explore causal trends for presentation and sheds light on some of the major threats to wildlife health.Although many of the causal factors reported are anthropogenic in origin, the database used in this study also includes physiologic maladies and traumatic injuries unknown in origin.Signs of respiratory, gastrointestinal, neurologic, and other physiologic problems may be the result of some disease process, but evidence of the source and specifics of these diseases or other processes are unclear and, therefore, not investigated.This study does not attempt to explain the origin or cause of all reasons for presentation, but rather focuses on the most frequent causes of presentation.
The most frequent categories-trauma and found/ abandoned/ orphaned do not explicitly imply direct human involvement, but they do highlight the importance of understanding how wildlife habitats are changing in response to both natural and unnatural disruptions.Although pathogen pollution, noise pollution, and environmental pollution, have been shown to lead to wildlife morbidity [1,2,[15][16][17], this study provides an additional explanation that "predator pollution, " by means of introducing domestic cats and dogs to wildlife areas, may also be having a profound and damaging effect.This study further supports the importance of reducing the impact human infringement has on native wildlife [18] in order to protect the health of the wildlife and support ecosystems.
With a standard deviation of 0.01, the percentage of overall cases seen each year did not differ dramatically.This may represent a minimal change in presentation frequency over the course of the eleven years included in this study, but further studies focused on temporal and seasonal trends would be helpful in further studying anthropogenic effects.
The data provided in this study does not investigate or support the role of environmental pollution, pesticide use, or other forms of habitat disruption, but it does lend itself to the needed discussion about the many factors contributing to the morbidity and Submit your next manuscript to Annex Publishers and benefit from: Submit your manuscript at http://www.annexpublishers.com/paper-submission.php→ Easy online submission process → Rapid peer review process → Open access: articles available free online → Online article availability soon after acceptance for Publication → Better discount on subsequent article submission → More accessibility of the articles to the readers/researchers within the field 19.U.S. Fish and Wildlife Service (2003) Recovery Plan for the Red-cockaded Woodpecker (Picoides borealis): Second Revision, Atlanta, GA, USA.20.Shepard B, Whittington J (2006) Response of wolves to corridor restoration and human use management.Ecology and Society, USA.21.Rosenberg DK, Noon BR, Meslow EC (1997) Biological corridors: Form, function, and efficacy.BioScience 47: 677-87.22. Goddard MA, Dougill AJ, Benton TG (2010) Scaling up from gardens: biodiversity conservation in urban environments.Trends Ecol Evol 25: 90-8.

Table 1 :
Frequency of common admitting/presenting signs for herptile, mammal, and avian species presented to a wildlife clinic in East Tennessee between 2000-2011