Wild animals are vulnerable to an enormous variety of threats in nature. The threat of physical injury is one of the most common. Nonhuman animals are often injured, sometimes resulting in death. The actual wounds may kill the animals, or their injuries may cripple them in ways that are fatal, such as certain types of mutilations. In other cases, even though they survive, their wounds cause a lot of suffering, especially from chronic pain when injuries do not heal properly.
Most physical injuries are due to inter and intra-specific interactions (e.g., predation or territorial disputes) but other natural causes may also cause injuries, such as flying accidents or exposure to excessive heat.
The condition of an injured animal is usually aggravated by the risk of infection and associated diseases. Some of the complications that can result from injuries in the wild are discussed below.
Many attacks do not succeed. Often, animals manage to escape a pursuer even when initially captured – see, for example, this video on a wildebeest escape.1 But terrible injuries may result from attacks by predators, which are usually sudden and brutally violent. They can involve compression, stretching, torsion, and puncture of tissues. Predators are the most common cause of injury, though physical trauma can also occur during interaction with members of the same species.
Survival strategies may injure animals even in their daily interactions. For example, animals chase and fight each other to protect territory or social structure, or, to establish a new social or mating hierarchy, (as among bears2 and ferrets3) or to protect their young.4 Also, competition for food, water, bedding, or other basic needs may lead to such aggressive behavior that injury becomes systematically involved.
Scientific evidence suggests that rape (sometimes referred to as forced copulation) is observed among some nonhuman animals, such as some species of waterfowl,5 bottle-nosed dolphins, and primates.6 The victim usually struggles and attempts to escape and is often immobilized by the attacker. In some cases it results in severe injury from actions like scalping (tearing the skin over the head) in waterfowl. The rape attempts can be made individually or in groups, like the “rape flights” performed by groups of drakes.7 The risk of injury is high and the severity of the act may lead to the drowning of the assaulted animal.5
Many animals sustain crushing injuries caused by accidental trauma. Crushing occurs when an individual becomes caught between the ground and a solid object, often a larger animal. The type and degree of the injury depends on the amount of force, resulting in a range of injuries from minor bruising to severe hemorrhage, fractures, and rupture of internal organs. This type of injury has been particularly observed in hedgehogs8 and waterfowl,9 though it can occur in animals of many other species.
Impact injury is a common cause of death in some species of wild animals, especially birds.9 Birds often collide during flights, resulting in crash landings. Young birds also commonly fall from nests. As a result, many individuals suffer from bruising, hemorrhage, and fracture, in particular of limbs and vertebra.10 In waterfowl, the most severe cause of impact injury are hailstorms.11 Survivors of hailstorms often have torn skin, damaged mandibles and internal organ damage.
Many wild animals have to face extreme climatic conditions (see weather conditions and nonhuman animals section). These conditions are often responsible for injury, such as skin burns. Burns may range from minor scorching to complete destruction of the skin and underlying tissues. The most severe wounds can be fatal. Burn wounds are usually caused by excessive exposure to direct, strong sunlight.12 However, they can also be due to lightning strikes13 or fires.14 In addition to the pain associated with the wound, burned animals are likely to experience complications such as dehydration, lethargy, and depression.
When an animal becomes injured but does not die, she may be suffering on many levels. Firstly, there is the pain of the wounds. An injured animal may experience intense pain and discomfort. In some cases, the pain is so grievous that the animal self-mutilates.15 Pain can also cause other behaviors that can become dangerous to the animal such as causing them to decrease their intake of food and water, leading to weight loss, breaking down muscles, and impairing breathing. Secondly, an injured animal is likely to suffer from a range of other problems due to infections and related diseases. In the absence of medical treatment, infection is a ‘natural’ correlate of wounding in the wild. Damaged tissues tend to become infected by parasites (known as myiasis). In addition to being extremely painful for the animal, parasitic infestation may cause additional complications such as diarrhea, vomiting, and visual disturbance.
Finally, the disabling effects of the injury –increased by the process of infection– jeopardize the animal’s wellbeing in many important respects. Most notably, the animals may not be able to escape from threatening situations or to keep up with their social group. They may also be unable to eat or drink adequately to promote healing or even to stay alive. Injured animals also become preferential targets for both predators and competitive members of their own species, which drastically increases the number of deaths in the wild. The correlation between poor physical condition and predation has been thoroughly discussed in the scientific literature.16 Predators do not hunt randomly but rather select individuals who seem weak, including those who show signs of illness. As an example, in research carried out by M.W. Miller and colleagues, it was determined that the rate of predation of deers by mountain lions had grown fourfold, due to increased prevalence of infection in the population of deers.17
If animal suffering matters, then the increase in predation should concern us. The suffering of wild animals does not seem to be relevantly different from that of domestic animals. From the animal’s point of view, the experience of being injured by a sharp wood stick in nature or by a steel knife wielded by a human is equally painful and stressful. A wounded animal suffers, no matter who or what causes that suffering. Arguably, wounding in the wild causes more suffering because of infection and associated complications. If we think that humans have a moral obligation to reduce animal suffering this should include all animals, domesticated and wild.
Humans often intervene in the wild to treat injured or sick animals.18 Nevertheless, intervention is justifiable only if one of the following conditions is met:
If we reject speciesism and believe that equal interests should be given equal consideration, there is no sound moral reason to object to intervening on behalf of wild animals, whenever it is within our power to alleviate their suffering.
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Figiel, Jr., C. R. & Semlitsch, R. D. (1991) “Effects on nonlethal injury and habitat complexity on predation in tadpole populations”, Canadian Journal of Zoology, 69, pp. 830-834.
Clutton-Brock, T. H. & Parker, G. A. (1995) “Sexual coercion in animal societies”, Animal Behaviour, 49, pp. 1345-1365.
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Cooper J. E. (1996) “Physical Injury”, in Fairbrother A.; Locke L. N. & Hoff G. L. (eds) Noninfectious disease of wildlife, 2nd ed., Ames: Iowa State University Press, pp. 157-172.
Delahay, R. J.; Smith, G. C. & Hutchings, M. R. (2008) Management of disease in wild mammals, New York: Springer.
Emlen, S. T. & Wrege, P. H. (1986) “Forced copulations and intra-specific parasitism: Two costs of social living in the white-fronted bee-eater”, Ethology, 71, pp. 2-29.
Harris, Reid N. (1989) “Nonlethal injury to organisms as a mechanism of population regulation”, The American Naturalist, 134, pp. 835-847 [accessed on 13 March 2013].
Heithaus, M.; Frid, A. & Dill, L. (2002) “Shark-inflicted injury frequencies, escape ability, and habitat use of green and loggerhead turtles”, Marine Biology, 140, pp. 229-236.
Jonhson, Pieter T. J.; Preu, E. R.; Sutherland, D. R.; Romansic, J. M.; Han, B. & Blaustein, A. R. (2006) “Adding infection to injury: synergistic effects of predation and parasitism on amphibian malformations”, Ecology, 87, pp. 2227-2235.
Olsson, Mats (1995) “Forced copulation and costly female resistance behavior in the Lake Eyre Dragon, Ctenophorus maculosus”, Herpetologica, 51, pp. 19-24.
Reimchen, T. E. (1988) “Inefficient predators and prey injuries in a population of giant stickleback”, Canadian Journal of Zoology, 66, pp. 2036-2044.
Reimchen, T. E. (1992) “Injuries on stickleback from attacks by a toothed predator (Oncorhynchus) and implications for the evolution of lateral plates”, Evolution, 46, pp. 1224-1230.
Schoener, T. W. (1979) “Inferring the properties of predation and other injury-producing agents from injury frequencies”, Ecology, 60, pp. 1110-1115.
Smuts, B. B. & Smuts, R. W. (1993) “Male aggression and sexual coercion of females in nonhuman primates and other mammals: Evidence and theoretical implications”, Advances in the Study of Behavior, 22, pp. 1-63.
2 Person, A. M. (1975) The northern interior grizzly bear Ursus arctos L., Ottawa: Information Canada, pp. 39-42.
3 Porter, V. & Brown, N. (1990 ) The complete book of ferrets, new ed. London: Pelham, pp. 67-79
5 McKinney, F & Evarts, S. (1998) “Sexual coercion in waterfowl and other birds”, Ornithological Monographs, 49, pp. 163-195.
6 Connor, R. & Vollmer, N. (2009) “Sexual coercion in dolphin consortships: A comparison with chimpanzees”, in Muller, M. N. & Wrangham, R. W. (eds.) Sexual coercion in primates and humans: An evolutionary perspective on male aggression against females, Cambridge: Harvard University Press, p. 218.
7 Bailey, R.; Seymour, N. & Stewart, G. (1978) “Rape behavior in blue-winged teal”, Short Communications, 95, pp. 188-190.
9 Bexton, S. & Robinson, I. (2003) “Hedgehogs”, in Mullineaux, E.; Best, R. & Cooper, J.E. (eds.) BSAVA manual of wildlife casualties, Quedgeley: British Small Animal Veterinary Association Year, pp. 49-65.
9 Beer, J. V. & Ogilvie, M. A. (1972) “Mortality”, in Scott, P. & The Wildfowl Trust (eds.) The swans, London: Michael Joseph, pp. 125-142.
10 Bush. M. (1986) “Laparoscopy and Surgery”, in Fowler, M.E. (ed.) Zoo & wild animal medicine, 2nd ed., Philadelphia: WB Saunders & Co., pp. 253-261.
11 Macdonald, J. W.; Goater, R.; Atkinson, N.K. & Small, J. (1990) “Further causes of death in Scottish swans (Cygnus spp.)”, State Veterinary Journal, 44, pp. 81-93.
12 Schmidt, M. (1986) “Elephants (Proboscidae)”, in Fowler, M.E. (ed.) Zoo & wild animal medicine, op. cit., pp. 883-923.
13 Evans, G. H. (1910) Elephants and their diseases: A treatise on elephants, Rangoon: Government Press.
14 du Toit, J. G. (2001) Veterinary care of african elephants, Pretoria: Novartis and south African Veterinary Foundation.
15 Lascalles, B. D. X. (1996) “Advances in control of pain in animals”, The Veterinary Annual, 36, pp. 1-15.
16 See for example, Curio, E. (1976) The ethology of predation, Berlin: Springer Verlag. Martín, J.; de Neve, L.; Polo, V. & Fargallo, J. A. (2006) “Health-dependent vulnerability to predation affects escape responses of unguarded chinstrap penguin chicks”, Behavioral Ecology and Sociobiology, 60 (6), pp. 778-784. Penteriani, V.; Delgado, M. M.; Bartolommei, P.; Maggio C.; Alonso-Álvarez, C. & Holloway, J. (2008) “Owls and rabbits: predation against substandard individuals of an easy prey”, Journal of Avian Biology, 39, pp. 215-221.
17 Miller, M. W.; Swanson, H. M.; Wolfe, L. L.; Quartarone F. G.; Huwer, S. L.; Southwick, C. H. & Lukacs, P. M. (2008) “Lions and prions and deer demise”, PLoS ONE, 3, e4019 [accessed on 13 February 2013].
18 Wildpro (2011) “Ruminant pain management”, Wildpro.twycrosszoo.org [accessed on 28 January 2013]; Wildpro (2011) “Managing foot-and-mouth disease”, Wildpro.twycrosszoo.org [accessed on 28 January 2013]; Wildpro (2011) “Elephant disease management”, Wildpro.twycrosszoo.org [accessed on 30 January 2013].