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Veterinary Aspects of Forensic Medicine: Wild Animals – Wildlife Forensic Pathology
Veterinary Aspects of Forensic Medicine: Wild Animals – Wildlife Forensic Pathology TC Viner, National Fish and Wildlife Forensics Laboratory, Ashland, OR, USA r 2016 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by K. Goddard, volume 4, pp 344–349, © 2005, Elsevier Ltd.
Abstract Forensic pathologic changes in animals are closely parallel to those in humans. Electrothermal burns, toxicities, and gunshot wounds cause similar effects to the body, whether that is the body of Homo sapiens or Canis lupus. This chapter describes some common results of human–wildlife and wildlife–wildlife conflict, and describes the techniques used in the forensic pathology investigation of wild animal death.
Glossary Alternate light source An equipment used to produce visible and invisible light at various wavelengths to enhance or visualize items of evidence (fluids, fingerprints, clothing fibers, etc.). The light will cause possible biological stains to change color or fluoresce, assisting in the location process. Anticholinergic insecticide A toxin that acts by inhibiting the physiological action of acetylcholine, especially as a neurotransmitter. Organophosphates and carbamates are examples of anticholinergic insecticides. Feather barb One of the parallel filaments projecting from the main shaft of a feather. Interspecific conflict A form of competition in which individuals of different species compete for the same resource in an ecosystem (e.g., food or living space). Intraspecific conflict A particular form of competition in which members of the same species vie for the same resource in an ecosystem (e.g., food, light, nutrients, or space).
Introduction The concept of One Health recognizes that pathogens and disease conditions behave similarly in human and nonhuman hosts, and the health of all species on this planet is impacted by environmental factors. The One Health model can also be applied to forensic science. As humans and wildlife are increasingly brought into close contact, conflict is almost inevitable, and the manifestation of this conflict bears striking resemblance to interhuman conflict. Other portions of this chapter explore the actions of ballistic projectiles on a body, the effects of electrocution, and the hallmarks of blunt force trauma, all agents of morbidity and mortality that also occur in wildlife species. The scientific principles behind gunshot trauma, powerline contact, and hit-bycar events can be translated across animal species, and the collaboration and cooperation of forensic scientists
Encyclopedia of Forensic and Legal Medicine, Volume 4
One Health One Health (formerly called One Medicine) is dedicated to improving the lives of all species – human and animal – through the integration of human medicine, veterinary medicine, and environmental science. Photoluminescence Photoluminescence describes the phenomenon of light emission from any form of matter after the absorption of photons. Photovoltaic panel A solar panel is a set of solar photovoltaic modules electrically connected and mounted on a supporting structure. Plastic-tipped bullet A type of bullet meant to confer the advantages of both spitzer and hollow-point bullets. Solar flux In radiometry, radiant flux or radiant power is the measure of the total power of electromagnetic radiation (including infrared, ultraviolet, and visible light). The power may be the total emitted from a source, or the total landing on a particular surface.
in both the human and veterinary medicine fields will strengthen and advance the knowledge and techniques of this brand of science. This chapter on wildlife forensics will outline some techniques used in the forensic investigation of wild animal death, and explore some of the common causes of death. While natural death from disease most certainly occurs in wild species, and inter- or intraspecific conflict may result in fatal injuries, the direct and indirect effects of humans in the environment have a significant impact on wild animal populations.
Techniques Radiography
Radiography is a valuable tool in the postmortem evaluation of a carcass. Full body radiographs taken in
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two views (lateral and dorsoventral/ventrodorsal) can reveal bullets or ballistic material and help to localize these items for retrieval and analysis. Radiographs can also show prior trauma that resulted in damage to bones. Skinning the Animal
The skin of most mammals and birds is largely covered and obscured by hair or feathers. This external layer hides changes – such as bruising, lacerations, and incisions – that can be more easily seen in the skin of humans. Shaving or plucking an entire animal to look for such changes is not logistically feasible. Most animals have a well-defined subcutaneous space, and
Figure 1 Skinning an animal completely can reveal pathologic changes – such as the multifocal hemorrhage in this gray wolf (Canis lupus) – that would be obscured by the hair coat (Photo by Rebecca A. Kagan).
separation of the skin from the underlying muscle or bone by skinning of the animal can help the examiner to visualize traumatic impacts on the skin (Figure 1). The skin is generally removed in one piece and as entirely as possible. Keeping the skin intact maintains the orientation and juxtaposition of anatomic structures and landmarks so that the physical location of lesions can be shown. Removal of the skin can also help to determine the trajectory of a projectile in gunshot cases. Plumage and pelage can be pulled through the skin and into a wound tract by a passing projectile. Careful removal of the skin can reveal entry wounds with hair or feathers extending from the outer surface of the skin, through the hole, and into the wound tract. Hair and feathers do not protrude into the hole of an exit wound. An alternate light source (ALS) can be utilized in the postmortem examination of wildlife cases. ALS can be used to identify fibers from clothing or packaging materials (e.g., ropes, snares, or blankets) on the hair coat or plumage that may indicate handling of the carcass prior to retrieval and analysis. The animal may also have been exposed to chemicals, which may leave residues on the body. Though indistinct to the naked eye, euthanasia solution may leave detectable residues in the plumage or pelage around an injection site, and the fluorescent labeling of cyanide can remain around and in the oral cavity after ingestion of bait. Physical changes in the feathers and fur can be highlighted by the use of an ALS. Singeing of the feathers and fur by electrothermal injury affords a photoluminescent quality when viewed at certain wavelengths (Viner et al., 2014). The often subtle changes in the adnexa that occur with powerline contact or lightning strike are made visibly obvious with the appropriate use of the ALS (Figures 2(a) and (b)).
Figure 2 Subtle changes in the feathers on the inner surface of the wing of this snow goose (Chen caerulescens; (a) were caused by lightning strike during flight. An alternate light source tuned to 570 nm and viewed with a red filter (b) causes the singed feathers to photoluminesce and become more obvious (Photo by Rebecca A. Kagan).
Veterinary Aspects of Forensic Medicine: Wild Animals – Wildlife Forensic Pathology
Trauma Gunshot
Ballistic trauma is one of the most common agents of illegal take in wildlife. Because of the nature of the human–wildlife relationship, most wild animal gunshot deaths are the result of long-range firing. Only when animals are trapped or injured are close- or intermediate-range injuries sustained. Damage to the bones and soft tissue in gunshot injury is reflective of the weapon used. Rifles are associated with the most damage to the body, often causing highly comminuted fractures, tearing of internal organs, and massive hemorrhage. Because of the lower velocity and character of shotgun projectiles, damage to tissues from a shotgun event is not as extensive as that produced from a similarly-distanced rifle event. Fragments of lead, copper, or steel bullets or pellets can be detected radiographically and visually within the wound tract. Occasionally, plastic tips – colored cones of plastic at the point of bullets – can be retrieved from the wound tract. The color and composition of these plastic tips is specific to certain makes and manufacturers of ammunition (Thompson et al., 2012), and their analysis can be valuable in narrowing down the range of weapons possibly used in cases where the remainder of the projectile is fragmented. Ballistic elements (bullet jackets and shot pellets) are frequently found chronically embedded in the soft tissues or bones of wild animals. These are generally the result of a nonfatal gunshot injury that has healed or is resolving. As in humans (Dienstknecht et al., 2012), embedded ballistic elements cause little to no clinical effect once bone and soft tissue damage and inflammation has resolved (De Francisco et al., 2003). Lead toxicosis is an infrequent sequel to nonlethal gunshot injury. The liver may be analyzed for lead levels in animals with embedded lead fragments. Results, however, should take into account the animal's feeding habits and behavior. Raptors, for example, may be exposed to lead when feeding on hunter-killed deer or offal, and the ingested lead may have already passed through the gastrointestinal (GI) tract at the time of testing. In scavengers such as these with elevated blood or liver lead levels, determining whether the lead was previously ingested or has been absorbed from the embedded metal particle is difficult or impossible.
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blunt force event occurred. Abrasive loss of hair may be associated with underlying contusions, which can be visualized under the skin in the subcutaneous space. Lacerations of the skin and organs occur when the elastic capacity of the tissue is exceeded by the impact. These changes must be differentiated from incisions that are made by sharp objects, such as knives. The edges of a laceration through the skin may be rounded or blunted, and connective tissue deep in the wound may exhibit bridging, creating an uneven deep surface. This manifestation contrasts with sharp incisions that are often wedge-shaped and of a consistent or evenly-graded depth in the deep parts of the wound. Contusions, or bruises, are commonly seen in blunt force events and result from breakage of small blood vessels in the soft tissues with extravasation of blood into the surrounding tissues. Contusions may occur in the skin or internal organs, and may be small and localized or widespread, depending on the character of the trauma. The shape and location of bruising in animals may reflect the item that caused the bruise. For example, bruising localized to opposite sides of a lower extremity may indicate that the animal had been caught in a leg hold trap. Bruising over a broad area of the trunk may indicate impact with a vehicle bumper. Blunt force trauma is most often incurred in animals, and especially wildlife, due to being hit by a vehicle (hit-by-car). At the time of impact, animals may attempt to grip the substrate on which they are standing, resulting in shredding of the nails or complete removal of claws (Figure 3). This change can be used in conjunction with abrasions and lacerations to support a claim of hit-by-car. Birds may suffer blunt force trauma or mortality due to striking glass panels. Windows of commercial or residential buildings often reflect vegetation that is attractive to birds, and can appear to present a clear flight
Blunt Force Trauma
Hallmarks of blunt force trauma include lacerations, abrasions, and contusions. These are easily identified in the hairless skin of humans, but can be difficult to see when covered by hair or feathers in nonhuman animals. Abrasions of the skin of mammals may be associated with shortening or removal of the hair. This damage to the hair coat may be the only outward indication that a
Figure 3 This mountain lion (Puma concolor) was hit by a car while standing on pavement. The claws were scraped across the pavement on impact and were shredded.
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path into open space (Klem et al., 2009). Additionally, photovoltaic panels or mirrors may reflect a clear, blue sky or appear to be inviting pools of water on which to land. Depending on the force of impact, birds may die instantly and be found at the base of the glass panel, fly away to later die of the injuries sustained, or may survive the impact with minimal injuries. Evidence at the scene that a bird has struck a glass panel may include feather dust silhouettes on the window or body feathers stuck to the pane at the point of impact. Feather dust may be highlighted by illuminating the pane with oblique light and viewing against a dark background. Window strike most often results in lacerations of internal organs in small birds (most often passerines) (Figure 4). Organs most often affected include the liver and heart. Similar to
Figure 4 Hemorrhage in the coelomic cavity of this juvenile yellowbellied sapsucker (Sphyrapicus varius) comes from four longitudinal liver lacerations (arrowheads) and a ruptured pericardium (arrows).
deceleration injury in humans, the great vessels at the heart base are often torn from the heart when small birds collide with glass panels. Bone fractures are seen more often in larger birds (e.g., raptors and pelicans) that strike glass panels. Sharp Force Trauma
Trauma due to incising objects is unusual in wildlife forensic cases. Knives are generally not the principal weapon used by humans in attempts to kill wild animals. The most common sharp weapon in use against wild land animals is the hunting arrow. Hunting tips may have two to four blades and are designed to cleanly enter the animal and cause deep lacerations of vital internal organs. The resultant and abundant hemorrhage ideally leads quickly to death of the animal. Occasionally, attempts are made to disguise an outof-season gunshot take as an arrow kill. In these instances, it is important to thoroughly examine the wound tract for signs consistent with the weapon(s) in question. Arrows may be inserted postmortem into gunshot entry or exit holes or, if these holes are not located, may be inserted into an undamaged portion of the body. Assessment of hemorrhage around the wound site can indicate whether an arrow wound is antemortem or postmortem (Figure 5). Arrows do not cause the temporary cavity effect that gunshot projectiles do; thus, tearing or shredding of soft tissues is absent. Additionally, arrows passing through bone or soft tissue will not leave residual metal within the wound tract. Metal seen in radiographs, or gunshot residues detected on the body point away from the arrow as the weapon used to kill the animal.
Figure 5 The arrow wound through the muscle and reflected skin on the left (a) is surrounded by hemorrhage, indicating antemortem trauma. The arrow-shaped lesion through the skin on the right (b) is devoid of hemorrhage and indicates a postmortem event (Photo by Richard K. Stroud).
Veterinary Aspects of Forensic Medicine: Wild Animals – Wildlife Forensic Pathology
Sharp force injuries may also be caused in marine mammals by rotating propeller blades (Lightsey et al., 2006). Lesions generally occur on the back and are characterized by parallel, linear, or shallow S-shaped evenly-spaced incisions to a consistently extensive depth in the soft tissues. Depending on the depth of the lesions and the extent of blood loss, the trauma may or may not be immediately fatal. Sublethal injury may result in local infection or thoracic pathology, such as pneumothorax, hemothorax, or pyothorax. A listing attitude exhibited by a live marine mammal in the water may indicate pathology within the chest cavity. Intraspecific Aggression
Aggression between wolves may result in fatalities that appear, on external examination, to resemble gunshot wounds. Punctures in the skin caused by the canine teeth are generally round and small, similar to bullet entry wounds, and may be single or in pairs. The damage to the underlying muscle, however, is distinctively different from the damage caused by ballistic impact. Wolves tend to bite and hold the neck, chest, limbs, or back of an opponent. In areas of large muscle mass, such as the neck, escape movements of the opponent against the bite hold of the wolf cause deep and irregular shredding of the musculature with abundant hemorrhage. Contraction of the damaged muscle results in cavitated defects in the tissue. This can be seen radiographically, as well as at gross postmortem exam (Figure 6).
Figure 6 Cavitation of the musculature on the dorsal aspect of the neck of wolves is consistent with interspecific aggression. The overlying lesions in the skin may be small and reflective of punctures delivered by the canine teeth. The muscle, a less elastic tissue, tears during wolf fights while the elasticity of the skin absorbs the pull of the teeth.
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Similarly, intraspecific aggression between eagles can result in penetrating wounds to the trunk and legs. Eagles perform aerial battles using their talons as the primary weapon. The talons, which can be up to 5 cm long, easily penetrate the thin skin of adversaries and dig into the muscle. Because the general format of eagle battle involves grab-and-release moves, damage to the muscle in opponents reflects penetrating injury and not shredding of the tissue as is commonly seen in wolf aggression. Talons may penetrate thin bones, such as the sternal plate, and the resulting hole should be differentiated from a bullet wound.
Industrial Mortality Energy Facilities
One of the most widely recognized, industry-related agents of wildlife mortality is powerline contact resulting in medium- to high-voltage electrocution. Electric power poles are attractive perching and nesting sites for many species of birds including raptors, song birds, and pigeons. Larger birds, such as eagles and ospreys, may inadvertently contact two points on the pole (either wire to ground or wire to wire), creating a circuit through the body of the bird that results in electrocution. Depending on the voltage of the contacted wire and the duration of contact, physical signs of electrocution may vary. High voltage powerline contact may result in extensive damage to feathers and soft tissues (Figure 7), including charring of the skin, rupture of internal organs (e.g., aorta and liver), and amputation of limbs. In these cases, physical evidence of powerline contact is obvious. Lower voltage powerline contact may result only in conduction disturbances in the heart (asystole or ventricular fibrillation), and physical burns or feather singeing may be subtle or absent. In these cases, the use of an alternate
Figure 7 Singed tail feathers and legs on the ventral aspect of a redtailed hawk (Buteo jamaicensis). Skin has been removed from the leg by the electrical trauma (arrow). Limb amputation is not unusual in cases of avian powerline contact.
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light source can greatly assist in locating singed feathers or skin. Additionally, muscle that has been exposed to an electric current may appear dry, brown, and ‘cooked.’ Wind turbines have also been recognized as causing mortality in bats, eagles, and other raptors (Pagel et al., 2013). Damage to the body is reflective of high-energy, blunt force impact. The high speed at the tip of a wind turbine blade may cause severe lacerations, resulting in amputation of limbs or bisection of the body of large birds, such as eagles. The character of the bony fractures ensuing from turbine blade collision is often comminuted and open in these animals. In smaller animals, such as bats, high-energy blunt impact by wind turbine blades may result in extensive bruising and fractures of the ribs, spine, and skull, as well as diaphragmatic herniation. In addition, and to a lesser extent than direct trauma, bats may be exposed to atmospheric cavitations caused by the movement of the turbine blade (Rollins et al., 2012). These cavitations cause damage to the lungs of the bats, similar to that seen in barotrauma. Solar energy generating facilities cause wildlife mortality in two major ways. As described in the ‘Blunt Force Trauma’ section, birds may collide with heliostats or mirrors due to the reflective quality of the panels. The resultant blunt impact may result in bruising, internal organ laceration, bony fractures, or compression damage to joints. Some solar facilities, termed ‘power tower’ facilities, generate power by reflecting the sun's rays from an array of mirrors that may cover up to 1000 acres onto a centrally located tower containing liquid that is superheated to run a generator. The convergence of the reflected rays around the tower results not only in greater illumination of the area, but also a very high solar flux. Solar flux is measured in watts and does not inherently possess a temperature value. However, similar to contact with power lines, flying animals
(birds and bats) exposed to this intense solar flux near the tower can suffer feather burns and soft tissue damage relative to the amount of solar flux to which the animal was exposed. Oil Pits/Spills
Skim pits, evaporation ponds, and reserve pits are above-ground or in-ground holding tanks used in the extraction and mining industries. When these tanks are left uncovered, they appear to be an attractive resting environment or water source for migratory birds. These pits, however, often contain either physical inhibitors or toxic chemicals that may harm animals. Oil or other thick fluid is a physical inhibitor that can coat the plumage of a bird, making it unable to fly. Additionally, environmental conditions may cause the oil to become extremely hot, causing hyperthermia in the trapped birds. Oil may also inhibit the insulative properties of the body feathers, resulting in hypothermia during colder weather. Spills of crude oil in rivers and oceans have a similar effect. Super-saline ponds also pose a physical inhibition when the salts crystalize on the plumage at the surface of the pond. The crystals grow around the nidus of feather barbs and also inhibit escape by flight (Figures 8(a) and (b)). A variety of chemicals are used in the mining and extraction industries and the clinical and pathological effects of the chemicals vary and are related to the compounds present in the pond. Cyanide is typically used in the extraction of precious metals and may be associated with mass wildlife mortalities. Sulfuric acid is used to assist the leaching process in waste ponds. When investigating wildlife deaths around an industrial pond, it is prudent to analyze the pond fluid for potential toxins, as gross and microscopic lesions in the affected animals may be subtle or absent, and autolysis may confound postmortem examination.
Figure 8 (a and b): A mallard (Anas platyrhynchos) that was trapped in a super-saline pond at a mining installation. Salt crystalized on the feathers after the mallard landed in the pond – note the heavy distribution of crystals where the water surface would touch the body. The salt increases the weight of the bird and disrupts the cohesiveness of the feathers barbs. These effects then prohibit flight and aerial escape from the pond.
Veterinary Aspects of Forensic Medicine: Wild Animals – Wildlife Forensic Pathology
Toxicosis Anticoagulants
Anticoagulants, such as brodifacoum and chlorophacinone, can cause morbidity and mortality in wild animals, especially those that feed on rodents. These small mammals are often the target of residential and commercial anticoagulant use and, when debilitated by the effects of the toxin, become easy prey for eagles, hawks, and owls. Most owls submitted to rehabilitation centers, regardless of clinical presentation, have elevated levels of anticoagulants detected in the blood or liver (Stone et al., 2003). As in rodents, exposure of birds to significant levels of anticoagulants can result in hemorrhage into body cavities, the gastrointestinal tract, or subcutaneous tissues. Relatively minor blunt trauma events may result in exaggerated hemorrhage at the point of impact, and death due to rapid blood loss. Low level, chronic exposure to anticoagulants often results in microvascular seepage of blood into the GI tract in the absence of frank hemorrhage (Figure 9). Postmortem changes consistent with chronic anticoagulant exposure include anemia with generalized soft tissue pallor; muscle wasting due to loss of protein through the GI tract; and scant, black, pasty gastrointestinal content. In raptors fitting this postmortem profile, anticoagulant exposure must be differentiated from lead ingestion by analysis of liver and/or blood samples. Lead
Plumbism is another common toxicosis in wild birds. Historically, lead fishing sinkers caused heavy losses in waterfowl that consumed the weights when dive feeding. More recent restrictions on the use of lead sinkers in the United States, United Kingdom, and Canada have greatly reduced the impacts on waterfowl populations. Lead, however, may be present in the environment as
Figure 9 Chronic exposure to anticoagulant rodenticides results in microvascular leakage of blood into the GI tract, as evidenced by dark discoloration of the intestines of this bald eagle (Haliaeetus leucocephalus). There is generalized pallor (anemia) without evidence of frank hemorrhage.
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components of batteries, paint, or mining waste, and is still a preferred material in the manufacture of ballistic projectiles for hunting purposes. Lead bullets are heavy and generally shatter on impact with a target, causing more extensive soft tissue damage than non-fragmenting bullets. These fragments may remain within the soft tissues and viscera, which is usually removed from the body by the hunter and left in the field (field dressing the animal). The offal piles containing the lead fragments are often scavenged by vultures and other raptors. The ingested lead may have one of two clinical outcomes. In birds that are highly sensitive to the effects of lead in the system, clinical signs of crop stasis, ataxia, and dull mentation may be seen within hours. Untreated, these birds may die with radiographically visible lead fragments within the upper GI tract. Elevated levels of lead detected in the liver and/or blood can confirm the diagnosis of acute lead toxicity. Birds repeatedly exposed to low levels of lead or that are more resistant to the effects of lead may lose weight and develop anemia related to chronic inanition and disease. In these birds, metal particles rarely remain within the system and cannot be detected radiographically. Exposure to lead over months to years can result in detectable lead isotopes in the flight feathers. Lifetime exposure to lead is reflected in the bones, as this tissue is a long-term reservoir for this element. Prosecution of acute and chronic lead toxicity is very difficult as birds may move away from the inciting gut pile prior to discovery and whole bullets that can be traced to specific firearms are rarely found in the body of the affected animal. Organophosphates and Carbamates
These anticholinergic compounds are used as insecticides for residential and commercial applications. Organophosphates and carbamates have anticholinergic properties and cause rapid central nervous system dysfunction. Properly used, these toxins should not be available for ingestion by nontarget, wild animals. However, scavengers are occasionally exposed through ingestion of a poisoned target animal or direct ingestion of a baited carcass. The neurologic effects of anticholinergic insecticides result in a characteristic death posture in eagles wherein the head and neck are thrown over the back, the shoulders are pulled together, the wings are slightly extended, and the talons are clenched (Figure 10). When multiple animals feed on a baited or poisoned carcass, many animals exhibiting this classic posture may ring the scavenged animal. Because these toxins act rapidly, the crop and gizzard of the affected birds may be full, indicating recent feeding activity. Suspicion of organophosphate/carbamate toxicity should be high in birds that otherwise appear healthy and well-muscled, but exhibit neurologic signs or a classic death pose, and have a full crop. Testing of
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many cases, the resolution may only be narrowed to a window of days or weeks.
Legal Note The findings and conclusions in this chapter are those of the author and do not necessarily represent the views of the US Fish and Wildlife Service.
Figure 10 Classic death pose of a bald eagle poisoned by an anticholinergic pesticide, e.g., organophosphate or carbamate (Photo by USFWS).
the recently ingested tissue by gas chromatography/mass spectroscopy can reveal the specific toxin involved in the poisoning event. Postmortem Change
Wild animals are rarely discovered within hours of their death. Thus, some degree of postmortem decomposition is almost always encountered during the forensic analysis of wildlife carcasses. Measurements of rectal temperature, rigor mortis, and chemical composition of ocular or synovial fluid, taphonomic metrics commonly used in time-since-death evaluation of humans, are generally invalidated by the length of time elapsed between death and necropsy examination. Because weather, environmental conditions, and scavengers have a large effect on a body left in the outof-doors, the veterinary forensic scientist should be familiar with the local conditions in their geographic jurisdiction. Postmortem lividity can be enhanced by freeze-thaw cycles during colder months and the health and activity status of the animal just prior to death. These accentuated changes must be differentiated from hemorrhage in a degraded carcass, especially when insect or vertebrate scavenging activity mimics signs of antemortem trauma. Effective time-since-death analysis in wildlife is often a team effort involving point-ofdiscovery environmental measurements, knowledge of potential scavenger ecology, prompt evaluation of the condition of the body, and analysis of botanical and insect evidence. Even with an abundance of data, in
See also: Anthropology: Taphonomy in the Forensic Context. Electric Shocks and Electrocution, Clinical Effects and Pathology. Injury, Fatal and Nonfatal: Blunt Force Injury. Injury, Fatal and Nonfatal: Firearm Injuries. Road Traffic Accidents: Air Bag-Related Injuries and Deaths
References De Francisco, N., Ruiz Troya, J.D., Agüera, E.I., 2003. Lead and lead toxicity in domestic and free living birds. Avian Pathology 32, 3–13. Dienstknecht, T., Horst, K., Sellei, R.M., et al., 2012. Indications for bullet removal: Overview of the literature, and clinical practice guidelines for European trauma surgeons. European Journal of Trauma Emergency Surgery 38, 89–93. Klem Jr., D., Ramer, D.J., Delacretaz, N., Gelb, Y., Saenger, P.G., 2009. Architectural and landscape risk factors associated with bird-glass collisions in an urban environment. Wilson Journal of Ornithology 121, 126–134. Lightsey, J.D., Rommel, S.A., Costidis, A.M., Pitchford, T.D., 2006. Methods used during gross necropsy to determine watercraft-related mortality in the Florida manatee (Tricheus mantus latriostris). Journal of Zoo and Wildlife Medicine 37, 262–275. Pagel, J.E., Kritz, K.J., Millsap, B.A., Murphy, R.K., 2013. Bald eagle and golden eagle mortalities at wind energy facilities in the contiguous United States. Journal of Raptor Research 47, 311–315. Rollins, K.E., Meyerholz, D.K., Johnson, G.D., Capparella, A.P., Loew, S.S., 2012. A forensic Investigation into the etiology of bat mortality at a wind farm: Barotrauma or traumatic injury? Veterinary Pathology 49, 362–371. Stone, W.B., Okoniewski, J.C., Stedelin, J.R., 2003. Anticoagulant rodenticides and raptors: Recent findings from New York, 1998-2001. Bulletin of Environmental Contamination and Toxicology 70, 34–40. Thompson, M.C., Lancaster, C.A., Banta, M.G., et al., 2012. Chemical properties of selected plastic-tipped bullets. Association of Firearm and Toolmark Examiners Journal 44, 38–46. Viner, T.C., Kagan, R.A., Johnson, J.L., 2014. Using an alternate light source to detect electrically signed feathers and hair in a forensic setting. Forensic Science International 234, e25–e29.
Relevant Websites http://www.fws.gov/lab/ National Fish and Wildlife Forensics Lab. http://www.fws.gov/le/ US Fish and Wildlife Service Office of Law Enforcement.
Abstract Forensic pathologic changes in animals are closely parallel to those in humans. Electrothermal burns, toxicities, and gunshot wounds cause similar effects to the body, whether that is the body of Homo sapiens or Canis lupus. This chapter describes some common results of human–wildlife and wildlife–wildlife conflict, and describes the techniques used in the forensic pathology investigation of wild animal death.
Glossary Alternate light source An equipment used to produce visible and invisible light at various wavelengths to enhance or visualize items of evidence (fluids, fingerprints, clothing fibers, etc.). The light will cause possible biological stains to change color or fluoresce, assisting in the location process. Anticholinergic insecticide A toxin that acts by inhibiting the physiological action of acetylcholine, especially as a neurotransmitter. Organophosphates and carbamates are examples of anticholinergic insecticides. Feather barb One of the parallel filaments projecting from the main shaft of a feather. Interspecific conflict A form of competition in which individuals of different species compete for the same resource in an ecosystem (e.g., food or living space). Intraspecific conflict A particular form of competition in which members of the same species vie for the same resource in an ecosystem (e.g., food, light, nutrients, or space).
Introduction The concept of One Health recognizes that pathogens and disease conditions behave similarly in human and nonhuman hosts, and the health of all species on this planet is impacted by environmental factors. The One Health model can also be applied to forensic science. As humans and wildlife are increasingly brought into close contact, conflict is almost inevitable, and the manifestation of this conflict bears striking resemblance to interhuman conflict. Other portions of this chapter explore the actions of ballistic projectiles on a body, the effects of electrocution, and the hallmarks of blunt force trauma, all agents of morbidity and mortality that also occur in wildlife species. The scientific principles behind gunshot trauma, powerline contact, and hit-bycar events can be translated across animal species, and the collaboration and cooperation of forensic scientists
Encyclopedia of Forensic and Legal Medicine, Volume 4
One Health One Health (formerly called One Medicine) is dedicated to improving the lives of all species – human and animal – through the integration of human medicine, veterinary medicine, and environmental science. Photoluminescence Photoluminescence describes the phenomenon of light emission from any form of matter after the absorption of photons. Photovoltaic panel A solar panel is a set of solar photovoltaic modules electrically connected and mounted on a supporting structure. Plastic-tipped bullet A type of bullet meant to confer the advantages of both spitzer and hollow-point bullets. Solar flux In radiometry, radiant flux or radiant power is the measure of the total power of electromagnetic radiation (including infrared, ultraviolet, and visible light). The power may be the total emitted from a source, or the total landing on a particular surface.
in both the human and veterinary medicine fields will strengthen and advance the knowledge and techniques of this brand of science. This chapter on wildlife forensics will outline some techniques used in the forensic investigation of wild animal death, and explore some of the common causes of death. While natural death from disease most certainly occurs in wild species, and inter- or intraspecific conflict may result in fatal injuries, the direct and indirect effects of humans in the environment have a significant impact on wild animal populations.
Techniques Radiography
Radiography is a valuable tool in the postmortem evaluation of a carcass. Full body radiographs taken in
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two views (lateral and dorsoventral/ventrodorsal) can reveal bullets or ballistic material and help to localize these items for retrieval and analysis. Radiographs can also show prior trauma that resulted in damage to bones. Skinning the Animal
The skin of most mammals and birds is largely covered and obscured by hair or feathers. This external layer hides changes – such as bruising, lacerations, and incisions – that can be more easily seen in the skin of humans. Shaving or plucking an entire animal to look for such changes is not logistically feasible. Most animals have a well-defined subcutaneous space, and
Figure 1 Skinning an animal completely can reveal pathologic changes – such as the multifocal hemorrhage in this gray wolf (Canis lupus) – that would be obscured by the hair coat (Photo by Rebecca A. Kagan).
separation of the skin from the underlying muscle or bone by skinning of the animal can help the examiner to visualize traumatic impacts on the skin (Figure 1). The skin is generally removed in one piece and as entirely as possible. Keeping the skin intact maintains the orientation and juxtaposition of anatomic structures and landmarks so that the physical location of lesions can be shown. Removal of the skin can also help to determine the trajectory of a projectile in gunshot cases. Plumage and pelage can be pulled through the skin and into a wound tract by a passing projectile. Careful removal of the skin can reveal entry wounds with hair or feathers extending from the outer surface of the skin, through the hole, and into the wound tract. Hair and feathers do not protrude into the hole of an exit wound. An alternate light source (ALS) can be utilized in the postmortem examination of wildlife cases. ALS can be used to identify fibers from clothing or packaging materials (e.g., ropes, snares, or blankets) on the hair coat or plumage that may indicate handling of the carcass prior to retrieval and analysis. The animal may also have been exposed to chemicals, which may leave residues on the body. Though indistinct to the naked eye, euthanasia solution may leave detectable residues in the plumage or pelage around an injection site, and the fluorescent labeling of cyanide can remain around and in the oral cavity after ingestion of bait. Physical changes in the feathers and fur can be highlighted by the use of an ALS. Singeing of the feathers and fur by electrothermal injury affords a photoluminescent quality when viewed at certain wavelengths (Viner et al., 2014). The often subtle changes in the adnexa that occur with powerline contact or lightning strike are made visibly obvious with the appropriate use of the ALS (Figures 2(a) and (b)).
Figure 2 Subtle changes in the feathers on the inner surface of the wing of this snow goose (Chen caerulescens; (a) were caused by lightning strike during flight. An alternate light source tuned to 570 nm and viewed with a red filter (b) causes the singed feathers to photoluminesce and become more obvious (Photo by Rebecca A. Kagan).
Veterinary Aspects of Forensic Medicine: Wild Animals – Wildlife Forensic Pathology
Trauma Gunshot
Ballistic trauma is one of the most common agents of illegal take in wildlife. Because of the nature of the human–wildlife relationship, most wild animal gunshot deaths are the result of long-range firing. Only when animals are trapped or injured are close- or intermediate-range injuries sustained. Damage to the bones and soft tissue in gunshot injury is reflective of the weapon used. Rifles are associated with the most damage to the body, often causing highly comminuted fractures, tearing of internal organs, and massive hemorrhage. Because of the lower velocity and character of shotgun projectiles, damage to tissues from a shotgun event is not as extensive as that produced from a similarly-distanced rifle event. Fragments of lead, copper, or steel bullets or pellets can be detected radiographically and visually within the wound tract. Occasionally, plastic tips – colored cones of plastic at the point of bullets – can be retrieved from the wound tract. The color and composition of these plastic tips is specific to certain makes and manufacturers of ammunition (Thompson et al., 2012), and their analysis can be valuable in narrowing down the range of weapons possibly used in cases where the remainder of the projectile is fragmented. Ballistic elements (bullet jackets and shot pellets) are frequently found chronically embedded in the soft tissues or bones of wild animals. These are generally the result of a nonfatal gunshot injury that has healed or is resolving. As in humans (Dienstknecht et al., 2012), embedded ballistic elements cause little to no clinical effect once bone and soft tissue damage and inflammation has resolved (De Francisco et al., 2003). Lead toxicosis is an infrequent sequel to nonlethal gunshot injury. The liver may be analyzed for lead levels in animals with embedded lead fragments. Results, however, should take into account the animal's feeding habits and behavior. Raptors, for example, may be exposed to lead when feeding on hunter-killed deer or offal, and the ingested lead may have already passed through the gastrointestinal (GI) tract at the time of testing. In scavengers such as these with elevated blood or liver lead levels, determining whether the lead was previously ingested or has been absorbed from the embedded metal particle is difficult or impossible.
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blunt force event occurred. Abrasive loss of hair may be associated with underlying contusions, which can be visualized under the skin in the subcutaneous space. Lacerations of the skin and organs occur when the elastic capacity of the tissue is exceeded by the impact. These changes must be differentiated from incisions that are made by sharp objects, such as knives. The edges of a laceration through the skin may be rounded or blunted, and connective tissue deep in the wound may exhibit bridging, creating an uneven deep surface. This manifestation contrasts with sharp incisions that are often wedge-shaped and of a consistent or evenly-graded depth in the deep parts of the wound. Contusions, or bruises, are commonly seen in blunt force events and result from breakage of small blood vessels in the soft tissues with extravasation of blood into the surrounding tissues. Contusions may occur in the skin or internal organs, and may be small and localized or widespread, depending on the character of the trauma. The shape and location of bruising in animals may reflect the item that caused the bruise. For example, bruising localized to opposite sides of a lower extremity may indicate that the animal had been caught in a leg hold trap. Bruising over a broad area of the trunk may indicate impact with a vehicle bumper. Blunt force trauma is most often incurred in animals, and especially wildlife, due to being hit by a vehicle (hit-by-car). At the time of impact, animals may attempt to grip the substrate on which they are standing, resulting in shredding of the nails or complete removal of claws (Figure 3). This change can be used in conjunction with abrasions and lacerations to support a claim of hit-by-car. Birds may suffer blunt force trauma or mortality due to striking glass panels. Windows of commercial or residential buildings often reflect vegetation that is attractive to birds, and can appear to present a clear flight
Blunt Force Trauma
Hallmarks of blunt force trauma include lacerations, abrasions, and contusions. These are easily identified in the hairless skin of humans, but can be difficult to see when covered by hair or feathers in nonhuman animals. Abrasions of the skin of mammals may be associated with shortening or removal of the hair. This damage to the hair coat may be the only outward indication that a
Figure 3 This mountain lion (Puma concolor) was hit by a car while standing on pavement. The claws were scraped across the pavement on impact and were shredded.
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path into open space (Klem et al., 2009). Additionally, photovoltaic panels or mirrors may reflect a clear, blue sky or appear to be inviting pools of water on which to land. Depending on the force of impact, birds may die instantly and be found at the base of the glass panel, fly away to later die of the injuries sustained, or may survive the impact with minimal injuries. Evidence at the scene that a bird has struck a glass panel may include feather dust silhouettes on the window or body feathers stuck to the pane at the point of impact. Feather dust may be highlighted by illuminating the pane with oblique light and viewing against a dark background. Window strike most often results in lacerations of internal organs in small birds (most often passerines) (Figure 4). Organs most often affected include the liver and heart. Similar to
Figure 4 Hemorrhage in the coelomic cavity of this juvenile yellowbellied sapsucker (Sphyrapicus varius) comes from four longitudinal liver lacerations (arrowheads) and a ruptured pericardium (arrows).
deceleration injury in humans, the great vessels at the heart base are often torn from the heart when small birds collide with glass panels. Bone fractures are seen more often in larger birds (e.g., raptors and pelicans) that strike glass panels. Sharp Force Trauma
Trauma due to incising objects is unusual in wildlife forensic cases. Knives are generally not the principal weapon used by humans in attempts to kill wild animals. The most common sharp weapon in use against wild land animals is the hunting arrow. Hunting tips may have two to four blades and are designed to cleanly enter the animal and cause deep lacerations of vital internal organs. The resultant and abundant hemorrhage ideally leads quickly to death of the animal. Occasionally, attempts are made to disguise an outof-season gunshot take as an arrow kill. In these instances, it is important to thoroughly examine the wound tract for signs consistent with the weapon(s) in question. Arrows may be inserted postmortem into gunshot entry or exit holes or, if these holes are not located, may be inserted into an undamaged portion of the body. Assessment of hemorrhage around the wound site can indicate whether an arrow wound is antemortem or postmortem (Figure 5). Arrows do not cause the temporary cavity effect that gunshot projectiles do; thus, tearing or shredding of soft tissues is absent. Additionally, arrows passing through bone or soft tissue will not leave residual metal within the wound tract. Metal seen in radiographs, or gunshot residues detected on the body point away from the arrow as the weapon used to kill the animal.
Figure 5 The arrow wound through the muscle and reflected skin on the left (a) is surrounded by hemorrhage, indicating antemortem trauma. The arrow-shaped lesion through the skin on the right (b) is devoid of hemorrhage and indicates a postmortem event (Photo by Richard K. Stroud).
Veterinary Aspects of Forensic Medicine: Wild Animals – Wildlife Forensic Pathology
Sharp force injuries may also be caused in marine mammals by rotating propeller blades (Lightsey et al., 2006). Lesions generally occur on the back and are characterized by parallel, linear, or shallow S-shaped evenly-spaced incisions to a consistently extensive depth in the soft tissues. Depending on the depth of the lesions and the extent of blood loss, the trauma may or may not be immediately fatal. Sublethal injury may result in local infection or thoracic pathology, such as pneumothorax, hemothorax, or pyothorax. A listing attitude exhibited by a live marine mammal in the water may indicate pathology within the chest cavity. Intraspecific Aggression
Aggression between wolves may result in fatalities that appear, on external examination, to resemble gunshot wounds. Punctures in the skin caused by the canine teeth are generally round and small, similar to bullet entry wounds, and may be single or in pairs. The damage to the underlying muscle, however, is distinctively different from the damage caused by ballistic impact. Wolves tend to bite and hold the neck, chest, limbs, or back of an opponent. In areas of large muscle mass, such as the neck, escape movements of the opponent against the bite hold of the wolf cause deep and irregular shredding of the musculature with abundant hemorrhage. Contraction of the damaged muscle results in cavitated defects in the tissue. This can be seen radiographically, as well as at gross postmortem exam (Figure 6).
Figure 6 Cavitation of the musculature on the dorsal aspect of the neck of wolves is consistent with interspecific aggression. The overlying lesions in the skin may be small and reflective of punctures delivered by the canine teeth. The muscle, a less elastic tissue, tears during wolf fights while the elasticity of the skin absorbs the pull of the teeth.
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Similarly, intraspecific aggression between eagles can result in penetrating wounds to the trunk and legs. Eagles perform aerial battles using their talons as the primary weapon. The talons, which can be up to 5 cm long, easily penetrate the thin skin of adversaries and dig into the muscle. Because the general format of eagle battle involves grab-and-release moves, damage to the muscle in opponents reflects penetrating injury and not shredding of the tissue as is commonly seen in wolf aggression. Talons may penetrate thin bones, such as the sternal plate, and the resulting hole should be differentiated from a bullet wound.
Industrial Mortality Energy Facilities
One of the most widely recognized, industry-related agents of wildlife mortality is powerline contact resulting in medium- to high-voltage electrocution. Electric power poles are attractive perching and nesting sites for many species of birds including raptors, song birds, and pigeons. Larger birds, such as eagles and ospreys, may inadvertently contact two points on the pole (either wire to ground or wire to wire), creating a circuit through the body of the bird that results in electrocution. Depending on the voltage of the contacted wire and the duration of contact, physical signs of electrocution may vary. High voltage powerline contact may result in extensive damage to feathers and soft tissues (Figure 7), including charring of the skin, rupture of internal organs (e.g., aorta and liver), and amputation of limbs. In these cases, physical evidence of powerline contact is obvious. Lower voltage powerline contact may result only in conduction disturbances in the heart (asystole or ventricular fibrillation), and physical burns or feather singeing may be subtle or absent. In these cases, the use of an alternate
Figure 7 Singed tail feathers and legs on the ventral aspect of a redtailed hawk (Buteo jamaicensis). Skin has been removed from the leg by the electrical trauma (arrow). Limb amputation is not unusual in cases of avian powerline contact.
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light source can greatly assist in locating singed feathers or skin. Additionally, muscle that has been exposed to an electric current may appear dry, brown, and ‘cooked.’ Wind turbines have also been recognized as causing mortality in bats, eagles, and other raptors (Pagel et al., 2013). Damage to the body is reflective of high-energy, blunt force impact. The high speed at the tip of a wind turbine blade may cause severe lacerations, resulting in amputation of limbs or bisection of the body of large birds, such as eagles. The character of the bony fractures ensuing from turbine blade collision is often comminuted and open in these animals. In smaller animals, such as bats, high-energy blunt impact by wind turbine blades may result in extensive bruising and fractures of the ribs, spine, and skull, as well as diaphragmatic herniation. In addition, and to a lesser extent than direct trauma, bats may be exposed to atmospheric cavitations caused by the movement of the turbine blade (Rollins et al., 2012). These cavitations cause damage to the lungs of the bats, similar to that seen in barotrauma. Solar energy generating facilities cause wildlife mortality in two major ways. As described in the ‘Blunt Force Trauma’ section, birds may collide with heliostats or mirrors due to the reflective quality of the panels. The resultant blunt impact may result in bruising, internal organ laceration, bony fractures, or compression damage to joints. Some solar facilities, termed ‘power tower’ facilities, generate power by reflecting the sun's rays from an array of mirrors that may cover up to 1000 acres onto a centrally located tower containing liquid that is superheated to run a generator. The convergence of the reflected rays around the tower results not only in greater illumination of the area, but also a very high solar flux. Solar flux is measured in watts and does not inherently possess a temperature value. However, similar to contact with power lines, flying animals
(birds and bats) exposed to this intense solar flux near the tower can suffer feather burns and soft tissue damage relative to the amount of solar flux to which the animal was exposed. Oil Pits/Spills
Skim pits, evaporation ponds, and reserve pits are above-ground or in-ground holding tanks used in the extraction and mining industries. When these tanks are left uncovered, they appear to be an attractive resting environment or water source for migratory birds. These pits, however, often contain either physical inhibitors or toxic chemicals that may harm animals. Oil or other thick fluid is a physical inhibitor that can coat the plumage of a bird, making it unable to fly. Additionally, environmental conditions may cause the oil to become extremely hot, causing hyperthermia in the trapped birds. Oil may also inhibit the insulative properties of the body feathers, resulting in hypothermia during colder weather. Spills of crude oil in rivers and oceans have a similar effect. Super-saline ponds also pose a physical inhibition when the salts crystalize on the plumage at the surface of the pond. The crystals grow around the nidus of feather barbs and also inhibit escape by flight (Figures 8(a) and (b)). A variety of chemicals are used in the mining and extraction industries and the clinical and pathological effects of the chemicals vary and are related to the compounds present in the pond. Cyanide is typically used in the extraction of precious metals and may be associated with mass wildlife mortalities. Sulfuric acid is used to assist the leaching process in waste ponds. When investigating wildlife deaths around an industrial pond, it is prudent to analyze the pond fluid for potential toxins, as gross and microscopic lesions in the affected animals may be subtle or absent, and autolysis may confound postmortem examination.
Figure 8 (a and b): A mallard (Anas platyrhynchos) that was trapped in a super-saline pond at a mining installation. Salt crystalized on the feathers after the mallard landed in the pond – note the heavy distribution of crystals where the water surface would touch the body. The salt increases the weight of the bird and disrupts the cohesiveness of the feathers barbs. These effects then prohibit flight and aerial escape from the pond.
Veterinary Aspects of Forensic Medicine: Wild Animals – Wildlife Forensic Pathology
Toxicosis Anticoagulants
Anticoagulants, such as brodifacoum and chlorophacinone, can cause morbidity and mortality in wild animals, especially those that feed on rodents. These small mammals are often the target of residential and commercial anticoagulant use and, when debilitated by the effects of the toxin, become easy prey for eagles, hawks, and owls. Most owls submitted to rehabilitation centers, regardless of clinical presentation, have elevated levels of anticoagulants detected in the blood or liver (Stone et al., 2003). As in rodents, exposure of birds to significant levels of anticoagulants can result in hemorrhage into body cavities, the gastrointestinal tract, or subcutaneous tissues. Relatively minor blunt trauma events may result in exaggerated hemorrhage at the point of impact, and death due to rapid blood loss. Low level, chronic exposure to anticoagulants often results in microvascular seepage of blood into the GI tract in the absence of frank hemorrhage (Figure 9). Postmortem changes consistent with chronic anticoagulant exposure include anemia with generalized soft tissue pallor; muscle wasting due to loss of protein through the GI tract; and scant, black, pasty gastrointestinal content. In raptors fitting this postmortem profile, anticoagulant exposure must be differentiated from lead ingestion by analysis of liver and/or blood samples. Lead
Plumbism is another common toxicosis in wild birds. Historically, lead fishing sinkers caused heavy losses in waterfowl that consumed the weights when dive feeding. More recent restrictions on the use of lead sinkers in the United States, United Kingdom, and Canada have greatly reduced the impacts on waterfowl populations. Lead, however, may be present in the environment as
Figure 9 Chronic exposure to anticoagulant rodenticides results in microvascular leakage of blood into the GI tract, as evidenced by dark discoloration of the intestines of this bald eagle (Haliaeetus leucocephalus). There is generalized pallor (anemia) without evidence of frank hemorrhage.
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components of batteries, paint, or mining waste, and is still a preferred material in the manufacture of ballistic projectiles for hunting purposes. Lead bullets are heavy and generally shatter on impact with a target, causing more extensive soft tissue damage than non-fragmenting bullets. These fragments may remain within the soft tissues and viscera, which is usually removed from the body by the hunter and left in the field (field dressing the animal). The offal piles containing the lead fragments are often scavenged by vultures and other raptors. The ingested lead may have one of two clinical outcomes. In birds that are highly sensitive to the effects of lead in the system, clinical signs of crop stasis, ataxia, and dull mentation may be seen within hours. Untreated, these birds may die with radiographically visible lead fragments within the upper GI tract. Elevated levels of lead detected in the liver and/or blood can confirm the diagnosis of acute lead toxicity. Birds repeatedly exposed to low levels of lead or that are more resistant to the effects of lead may lose weight and develop anemia related to chronic inanition and disease. In these birds, metal particles rarely remain within the system and cannot be detected radiographically. Exposure to lead over months to years can result in detectable lead isotopes in the flight feathers. Lifetime exposure to lead is reflected in the bones, as this tissue is a long-term reservoir for this element. Prosecution of acute and chronic lead toxicity is very difficult as birds may move away from the inciting gut pile prior to discovery and whole bullets that can be traced to specific firearms are rarely found in the body of the affected animal. Organophosphates and Carbamates
These anticholinergic compounds are used as insecticides for residential and commercial applications. Organophosphates and carbamates have anticholinergic properties and cause rapid central nervous system dysfunction. Properly used, these toxins should not be available for ingestion by nontarget, wild animals. However, scavengers are occasionally exposed through ingestion of a poisoned target animal or direct ingestion of a baited carcass. The neurologic effects of anticholinergic insecticides result in a characteristic death posture in eagles wherein the head and neck are thrown over the back, the shoulders are pulled together, the wings are slightly extended, and the talons are clenched (Figure 10). When multiple animals feed on a baited or poisoned carcass, many animals exhibiting this classic posture may ring the scavenged animal. Because these toxins act rapidly, the crop and gizzard of the affected birds may be full, indicating recent feeding activity. Suspicion of organophosphate/carbamate toxicity should be high in birds that otherwise appear healthy and well-muscled, but exhibit neurologic signs or a classic death pose, and have a full crop. Testing of
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many cases, the resolution may only be narrowed to a window of days or weeks.
Legal Note The findings and conclusions in this chapter are those of the author and do not necessarily represent the views of the US Fish and Wildlife Service.
Figure 10 Classic death pose of a bald eagle poisoned by an anticholinergic pesticide, e.g., organophosphate or carbamate (Photo by USFWS).
the recently ingested tissue by gas chromatography/mass spectroscopy can reveal the specific toxin involved in the poisoning event. Postmortem Change
Wild animals are rarely discovered within hours of their death. Thus, some degree of postmortem decomposition is almost always encountered during the forensic analysis of wildlife carcasses. Measurements of rectal temperature, rigor mortis, and chemical composition of ocular or synovial fluid, taphonomic metrics commonly used in time-since-death evaluation of humans, are generally invalidated by the length of time elapsed between death and necropsy examination. Because weather, environmental conditions, and scavengers have a large effect on a body left in the outof-doors, the veterinary forensic scientist should be familiar with the local conditions in their geographic jurisdiction. Postmortem lividity can be enhanced by freeze-thaw cycles during colder months and the health and activity status of the animal just prior to death. These accentuated changes must be differentiated from hemorrhage in a degraded carcass, especially when insect or vertebrate scavenging activity mimics signs of antemortem trauma. Effective time-since-death analysis in wildlife is often a team effort involving point-ofdiscovery environmental measurements, knowledge of potential scavenger ecology, prompt evaluation of the condition of the body, and analysis of botanical and insect evidence. Even with an abundance of data, in
See also: Anthropology: Taphonomy in the Forensic Context. Electric Shocks and Electrocution, Clinical Effects and Pathology. Injury, Fatal and Nonfatal: Blunt Force Injury. Injury, Fatal and Nonfatal: Firearm Injuries. Road Traffic Accidents: Air Bag-Related Injuries and Deaths
References De Francisco, N., Ruiz Troya, J.D., Agüera, E.I., 2003. Lead and lead toxicity in domestic and free living birds. Avian Pathology 32, 3–13. Dienstknecht, T., Horst, K., Sellei, R.M., et al., 2012. Indications for bullet removal: Overview of the literature, and clinical practice guidelines for European trauma surgeons. European Journal of Trauma Emergency Surgery 38, 89–93. Klem Jr., D., Ramer, D.J., Delacretaz, N., Gelb, Y., Saenger, P.G., 2009. Architectural and landscape risk factors associated with bird-glass collisions in an urban environment. Wilson Journal of Ornithology 121, 126–134. Lightsey, J.D., Rommel, S.A., Costidis, A.M., Pitchford, T.D., 2006. Methods used during gross necropsy to determine watercraft-related mortality in the Florida manatee (Tricheus mantus latriostris). Journal of Zoo and Wildlife Medicine 37, 262–275. Pagel, J.E., Kritz, K.J., Millsap, B.A., Murphy, R.K., 2013. Bald eagle and golden eagle mortalities at wind energy facilities in the contiguous United States. Journal of Raptor Research 47, 311–315. Rollins, K.E., Meyerholz, D.K., Johnson, G.D., Capparella, A.P., Loew, S.S., 2012. A forensic Investigation into the etiology of bat mortality at a wind farm: Barotrauma or traumatic injury? Veterinary Pathology 49, 362–371. Stone, W.B., Okoniewski, J.C., Stedelin, J.R., 2003. Anticoagulant rodenticides and raptors: Recent findings from New York, 1998-2001. Bulletin of Environmental Contamination and Toxicology 70, 34–40. Thompson, M.C., Lancaster, C.A., Banta, M.G., et al., 2012. Chemical properties of selected plastic-tipped bullets. Association of Firearm and Toolmark Examiners Journal 44, 38–46. Viner, T.C., Kagan, R.A., Johnson, J.L., 2014. Using an alternate light source to detect electrically signed feathers and hair in a forensic setting. Forensic Science International 234, e25–e29.
Relevant Websites http://www.fws.gov/lab/ National Fish and Wildlife Forensics Lab. http://www.fws.gov/le/ US Fish and Wildlife Service Office of Law Enforcement.