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ENCYCLOPEDIA OF ANIMAL RIGHTS AND ANIMAL WELFARE
Edited by Marc Bekoff
with Carron A. Meaney Foreword by Jane Goodall
Greenwood Press Westport, Connecticut
156
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ENRICHMENT
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dead-end these lines. Relevant differences make the two as morally distinct as death by natural causes is from murder. Selected Bibliography. Gunn, Alastair S., Preserving Rare Species, in Tom Regan (Ed.), Earthbound: New Introductory Essaysin Environmental Ethics (New York: Random House, 1984); Norton, Bryan G. (Ed.), The Preservation of Speczes(Pnnceton, NJ: Princeton University Press, 1986); Rolston, Holmes, Conserving Natural Value (New York: Columbia University Press, 1994); Rolston, Holmes, EnViromnental EthicS (Philadelphia: Temple University Press, 1988); Wilson, E. 0., The DIVersity of Life (Cambridge , MA: Belknap Press of Harvard University Press, 1992). HOLMES ROLSTON III
2. Simple objects such as balls can be rotated with other toys, and where possible, some possibility for their animation can be provided. A ball suspended tetherball style will often lead to greater interaction and entertainment for animals than one simply thrown in their living space. 3. Most young animals love to explore new situations. A trip to the local toy store may yield giant, durably made building elements that may be assembled and reassembled into ever-changing steps to climb and holes to dive into. 4. A simple switch or motion detector can be used to allow animals to control various parts of the environment. The range of opportunities is limited only by imagination and budget. Inexpensive suggestions include allowing animals to control the dimming or brightening of lights in their room; to control radios, televisions, or video recorders (perhaps even with motion pictures of their favorite companions to entertain themselves while humans are at work); to rotate a wheel or perform other exercise to deliver food treats; or to turn on showers or mists in which to play.
ENRICHMENT FOR ANIMALS During the past 25 years the recognition that captive wild animals are in need of richer environments than those traditionally afforded them has ?ecome the accepted norm. Often this recognition has spurred the pro.ductIOn of more beneficial behavioral conditions for animals in our care, but m some cases it has resulted in richer-appearing environments that please humans, but do little or nothing to improve the animals' well-being:* Th~ term "e~richment" might better be limited to those circumst~nces.m which ~ere IS measurable improvement in the behavioral and physIOlogical well-bemg of the animal. . . Historically, there were distinctions between "behavIOral e~nchment "dan "environmental enrichment." These were based on suggestlons tha~ there were two radically different approaches to improving the lot .of captlve a~imals. The behavioral enrichment approach focused on engmee~mg e~vIronments that provided opportunities that were likely to elicit spe.Cles-~lcal behaviors. For example, occasionally producing the sounds of cnckets m an otter exhibit and providing means by which the otters. could .hunt and ~apture crickets resulted in considerable display of speCles-typlc~l. behaVl.ors. Supporters of environmental enrichment suggest.ed ~at pro~Tld~ng"anch,~ enough environment precluded the need for engl~eenng artlficlal hunts or other apparatus that rewarded animals for partlc~lar respon~es. For ex: ample, if a captive forest with sufficient .foo.dwas proVIded for chm~panze~s, this might be sufficient to encourage significant .amount~, ~f spe~les-typlcal behaviors. Today, the term "environmental ennchment I~ typlc.ally used to refer to all efforts to improve the circumstances of captlve alllmais (s~e also ZOOS). Methods of providing more stimulating environments fo~ alllmals obviously depend on the species involved, but so~e exa~ples of simple and inexpensive methods that will serve for many alllmais mclude the following: 1. Provide interesting ways for them to hunt for food. Hide their ~rovisio~s in tr~es
or behind objects in ever-varying ways so that they may have the JOY d lscovenng of them.
Selected Bibliography. Markowitz, H., Behavioral Enrichment in the Zoo (New York: Van Nostrand Reinhold, 1982); Markowitz, H., and C. Aday, Power for Captive Animals: Contingencies and Nature, in D. Shepherds on, J. Mellen, and M. Hutchins (Eds.), Second Nature: Environmental Enrichment for Captive Animals (Washington, DC: Smithsonian Institution Press, 1998); Markowitz, R., C. Aday, and A. Gavassi, Effectiveness of Acoustic "Prey": Environmental Enrichment for a Captive African Leopard (Panthera pardus), Zoo Biology 14 (1995): 371-379; Markowitz, R., and A. Gavassi, Eleven Principles for Improving the Quality of Captive Animal Life, Lab Animal 24 (1995): 30-33; Markowitz, H., and S. W. Line, The Need for Responsive Environments, in B. E. Rollin and M. L. Kesel (Eds.), The Experimental Animal in BiomedicalResearch,vol. 1 (Boca Raton, FL: CRC Press, 1990), 153170.
HAL MARKOWITZ Enrichment and Research Changes in the conditions under which animals are kept that appear superficially to improve animals' lives do not always have the desired effect. Such contradictory results have most often been found when animals are kept in large numbers under standardized conditions on farms or in laboratories. To measure effects of proposed improvements in living conditions on the welfare of large numbers of animals usually requires carefully designed experiments. If you want to know whether changing the diet of 1,000 rats in a laboratory colony improves their health, you have to keep careful records of the animals' condition before and after the diet change to see if the new diet really improves the health of colony members. "Enrichment" has potential costs as well as potential benefits. On the surface, it seems likely that an animal living with others or in an interesting environment would be happier than an animal that spends its entire life alone in a standard laboratory cage. But consider the Norway rat, a common laboratory animal. When placed together, groups of male rats will engage in a
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or more males series of fights and form a dominance hierarchy with ~ne dominant over the rest. Subordinate individuals are contmually harassed by dominant animals, and within the confines of a laboratOry cage, subordinate rats are forced into constant contact with their superiors. Enhancement of the physical environment can also have undesired side effects. Consider the Mongolian gerbil. Gerbils are easy to handle and do not appear stressed by interaction with humans. However, if you provide.dIg ~o a breeding pair of gerbils with an environment where they.are free tunnels (as they do in nature) and allow them to rear theIr young m the underground nest chambers they construct, such young behave strangely when they are grown. They flee when you attempt to pick them up. When captured, they frequently have seizures. Here, ennch~ent seems to de~rease, not increase, the well-being* of animals who are gomg to spend theIr lIves . . interacting with humans. . Other attempts to improve the well-bemg of caged anIm.als may have SImbecause ilar paradoxical effects, not because of the nature of the anImals, but. of the economics of animal maintenance. Most people seem to belIeve that off the animal the larger the enclosure in which an animal is kept, ~he .bett~r will be. However, rats in nature spend most of theIr lIves m burrows consisting of small nest chambers connected by even smaller tun~els. a chOIce Perh~ps rats like to be kept in closely confined spaces. In fact, w~en gt~e~ between tall cages and short ones, rats are nonresponsIve. SImilarly, researchers at Oxford University in England have found that domesticated hens raised in the cramped "battery cages" (see CHICKENS) used for commercial egg production show no preference when given the choice between a large pen and a battery cage. Existing standards for animal maintenance have evolved over. the years with revisions based on professional judgment and personal evaluatlOn~. Su~h informal development of standards for animal maintenance does not mspIre confidence that the procedures in use today are optimal. On the other hand, the equally personal basis for many proposed changes in ~aintenance procedures suggests that such changes may not have the desired result of.enhancing the well-being of animals. Paradoxical consequen~es of alt~ratlO~s in maintenance conditions intended to improve the well-bemg of anImals m laboratories and on farms are likely. More research on consequences for animals of proposed changes in living conditions is needed. (See also LABORATORY ANIMAL USE.) Reari~g Selected Bibliography. Clark, M. M., and B. G. Galef, Jr., Effects ~f Environment on Adrenal Weights, Sexual Development, Journal of Comparative and Hypothesis, and BehavIOr III Gerbils: An Examination of Richter's Domestication PhysiologicalPsychology94 (1980): 857-863; Dawkins, M. S., Do Hens Suffer in Battery Cages? Environmental Preferences and Welfare, Amm~l Behav/~ur 25 (19?7): 10341046; Dawkins, M. S., From an Animal's Point of View: Motlvatlon, Fitness, and Animal Welfare, Behavioral and Brain Sciences 13 (1990): 1-61; Galef, B. G.,Jr., and
P; DurIach, Should Large Rats Be Housed in Large Cages' An Empirical Issue ' CanadianPsychology 34 (1993): 203-207.
BENNETT G. GALEF, JR.
ENVIRONMENTAL
ETHICS
Anthropocentric (human-centered) environmental ethics bases concern for the ~onhuman natural environment (including animals) on the benefits it provides ~umans. It treats only humans as of direct and intrinsic moral con-
cern. T~king care of a pet (see COMPANION ANIMALS AND PETS) or
a park IS done solely because they are useful to us. Anthropocentrism* is often defended by appeals to biblical passages that give humans "dominion over. . . every living thing ~hat ~oves upon the earth" (Genesis 1:28). In contras~, nonanthrop.oc~ntr~c ~nvlronmental ethics bases the protection of ~he envIro~ment on ItS mtrmsIC value. It conceives of nonhuman nature as Important m ways that surpass its instrumental (or use) value to humans
sentiocentric (sentience-centered; see SENTIENTISM) environme~tal ethic ho~ds that se~tient. creatures-those who can feel and perceive-are m~rally Important m their own right. Some of the best-known defenders of ammals accept th!s ethic, including Peter Singer. Because it is likely that only ~ertebrate ammals-n:ammals, birds, fish,* amphibians,* and reptiles*conscIOusly feel and perceIve, a sentiocentric environmental ethic treats inverteb:ate nature as solely of instrumental value for sentient creatures. Such an ethIc protects trees and ecosystems, for example, not for their own sake ' but because they provide a habitat for sentient creatures. Sentiocentrism ruptures ~e ~oun.dary of the traditional human-only mora~ club a~d may have radIcal ImplIcations for animal agriculture, animal exp~nmentatlOn, a~d hunti.ng.* Nonetheless, from the perspective of broader e~~Ironmen.tal ethIcs, sentIocentrism is but a small modification of the tradItlO~al ethIc. It ~xtends. moral concern beyond humans only to our closest c?~sms, .the sentient anImals, and denies direct moral concern to 99% of lIvmg bemgs ~n the planet, as well as species and ecosystems. Sentiocentrists respond that .It makes ~o sens.e t~ care directly about trees or ecosystems and that the Idea of owmg oblIgatIOns to bacteria is foolish. Biocentric. (life-centered) environmental ethics views all living beings as wort~y of direct moral concern. Biocentrists contend that although plants and mverteb:ate animals do not have preferences, they nonetheless have goods of.th.eIr own that we should morally consider. Though a tree does not care If ItS roots are crushed by a bulldozer, crushed roots are still bad f?~ the t~ee and not just for the homeowner who wants its shade. Insentient h~ng bemgs have a welfare of their own that should be part of direct enVIronmental concern. Albert Schweitzer's* reverence-for-life ethic is an example of biocentrism.
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