The Importance of Behavioural Studies in Conservation Biology
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ANIMAL BEHAVIOUR, 1998, 56, 801–809 Article No. ar980896 REVIEW The importance of behavioural studies in conservation biology WILLIAM J. SUTHERLAND School of Biological Sciences, University of East Anglia (Received 27 March 1998; initial acceptance 24 April 1998; final acceptance 29 May 1998; MS. number: RV2) ABSTRACT The exciting research developments in animal behaviour over the last two decades have had a negligible impact on conservation. I list 20 subjects in which the study of animal behaviour can make a significant contribution to conservation. Behaviour may in itself be worth conserving. I also suggest how behavioural ecologists could become more involved in conservation. 1998 The Association for the Study of Animal Behaviour onservation is an excellent subject for research by conservation, there are increasing amounts of money C those interested in behaviour. As well as obviously available to study conservation, there are books and there being important in its own right, the solving of conser- have been conferences linking the two subjects (Ulfstrand vation problems is often intellectually stimulating and 1996; Clemmons & Buchholz 1997; Caro, in press; conservation helps ensure the persistence of subjects for Gosling & Sutherland, in press), I doubt that editors and future behavioural research. conference organizers show a prejudice against conser- In view of the exciting research developments in ani- vation papers or talks, yet there is a clear gap between the mal behaviour, it is surprising that this subject has made two subjects. a negligible contribution to conservation biology. In It is remarkable that the animal behaviour community Table 1, I have summarized the subjects of 229 papers seems to have shown so little interest in conservation, from the 1996 volume of Animal Behaviour and 97 from unlike the population biology or genetics community. I Conservation Biology. There is a complete lack of papers in think one problem is that those studying animal behav- Animal Behaviour that directly relate to conservation. iour do not believe they have an important role to play in Although nine papers in Conservation Biology include an conservation biology. I also suspect that the priorities are aspect of behaviour in the title, most of the behavioural to remove the prejudice amongst those studying animal papers in that journal are descriptive (but still useful) behaviour that conservation is dull and not intellectually studies of subjects such as the use of corridors and challenging and remove the prejudice amongst conser- changes in time budgets in response to human distur- vation biologists that animal behaviour is of little rel- bance. It is remarkable that current conservation seems evance and, if really necessary, can be studied without to make so little use of the revolution in behavioural any background in the subject. ecology of the last 20 years. There is little use of modern developments in subjects such as game theory, sperm Table 1. Classification of subjects of research papers in the journals competition, cultural evolution, learning or breeding Animal Behaviour and Conservation Biology in 1996 systems. Similarly, at the latest (1997) International Ethological Journal Conference there was little evidence from the talks or poster sessions of a real interest in answering conser- Animal Conservation vation problems (1.6%: nine out of 577 of the papers Subject Behaviour Biology related to conservation). Students seem keen to study Conservation 0 88 Correspondence: W. J. Sutherland, School of Biological Sciences, Behaviour 229 0 University of East Anglia, Norwich NR4 7TJ, U.K. (email: Conservation and behaviour 0 9 [email protected]) 0003–3472/98/100801+09 $30.00/0 801 1998 The Association for the Study of Animal Behaviour 802 ANIMAL BEHAVIOUR, 56, 4 If most animal behaviour research were directed at helpers reduce their parents’ success and only 23% are applied problems, such as conservation biology, the females. Phenomena such as these must greatly alter the subject could well be less exciting and develop more extinction probabilities. slowly conceptually. It would, however, seem appropriate that a reasonable percentage (say 10%) of papers in journals and talks at meetings should have applied impli- Mating Systems and Inbreeding Depression cations. Furthermore, there are likely to be increasing The level of inbreeding depression will depend upon calls to justify our research funding and it would be useful the level of homozygosity, which is in turn related to the to be able to point to practical applications. effective population size, which in turn is related to the mating system (Seal 1985). Understanding the relation- ship between breeding system and inbreeding depression HOW BEHAVIOURAL STUDIES CAN HELP will help us to understand when inbreeding depression is CONSERVATION likely to be a problem. There is also the possibility I list 20 areas in which I believe that the study of animal of manipulating the social system to alter effective behaviour should be providing a major contribution to population size. solving conservation problems. This is not intended to be an exhaustive list: I have concentrated on those areas Species Isolation in which behavioural studies could make a substantial contribution to a subject area. Species diversity obviously depends upon species remaining genetically isolated and whether this happens often depends upon the details of the behaviour. Small Population Extinctions Seehaussen et al. (1997) showed that in Lake Victoria recently increased turbidity, as a result of deforestation Small populations decline and go extinct for many and agricultural practices, constrains the colour vision of reasons, some of which are behavioural. For example, cichlid fish, thus interferes with mate choice and so there may be members of each sex present in the popu- blocks reproductive isolation. Eutrophication leads to a lation yet they fail to breed successfully. The Allee effect community of low species diversity, few colour morphs (Allee 1931) describes such a decline in population and dull-coloured fish. growth rate at low population sizes, but the behavioural Hybridization between native and nonindigenous component of this has attracted little research. For species is becoming a widespread problem (Simberloff example, it would be useful to know if species with 1998). Two species may hybridize such that the native communal displays, such as leks, are most susceptible to species disappears through introgression, as is the case small population extinctions. Small populations of plants with the introduced ruddy duck, Oxyura jamaicensis,in could also experience reduced pollination as a result of Europe mating with the native white-headed duck, changes in the behaviour of pollinators. Very small popu- Oxyura leucophela. Alternatively the hybrid fetus may lations may experience greater predation as a result of abort or the resulting offspring may be infertile resulting reduced vigilance or group defence. Some species are in a reduction in fertility. For example, the introduced more likely to breed in the presence of conspecifics (Reed American mink, Mustela vison, is greatly affecting the & Dobson 1993). The obvious implication of this research reproduction of the European mink, Mustela lutreola,as is that it may then be possible to find ways of reducing the hybrid fetus aborts and the female loses a breeding extinction risk and to identify the risks of allowing a season (Rozhnov 1993). population to become small. If a pair of species will hybridize, then the consequence The fate of small populations may also be linked to for each species will greatly depend upon the details of sexual selection. Studies of the fate of populations of mating behaviour and mate choice. In the cases described introduced birds in Tahiti and Oatu (McLain et al. 1995) above, the white-headed duck females seem to prefer and in New Zealand (Sorci et al., in press) showed that the males of ruddy ducks to conspecifics and because the probability of extinction was higher if the species was American mink males reproduce earlier the female sexually dichromatic. This can be interpreted in terms of European mink mates disproportionately with them exaggerated ornamentation or coloration that promotes (Simberloff 1998). Thus the behavioural details determine reproductive success also reducing survival (Lande 1980; the severity of the problem. Sutherland & De Jong 1991) thus potentially reducing the population size or growth rate. An understanding of the manner in which the sex ratio Dispersal in Fragmented Populations changes with population density and environmental conditions will also have implications. For example, Habitat fragmentation is a major conservation issue. As Komdeur et al. (1997) showed considerable distortions of a habitat becomes more fragmented, it becomes increas- the sex ratio of Seychelles warblers, Acrocephalus seychel- ingly unlikely that a patch will be recolonized after local lensis, in response to differences in habitat. Helpers are extinction. A major issue in understanding the conse- usually females. On good quality territories, helpers quences of fragmenting habitats on populations or meta- increase the reproductive success of their parents populations is the behaviour of dispersing individuals. If and 87% of young are females. On poor territories an individual can search an infinite area then any patch REVIEW 803 can be located, but with a more realistic assumption of Reducing Predation restricted