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Behavioural ecology was born over thirty years ago as a result of the merging of evolutionary theories and classical ethology (Sutherland W.J, & Gosling L.M, . 2000). Behavioural Ecologists it is understood on the one hand are concerned with animal interactions that include both their biotic and abiotic environments inclusive of to what extent these interactions and behavioural characteristics have evolved. Conservation Biologists on the other hand focus on multiple disciplines concerning the Conservation of Biodiversity (Sutherland & Gosling, 2000) and the threat to the natural world from anthropogenic development and activities (Pullin, 2002). Through understandings gained from interactions; examples of which are; feeding, breeding, territoriality, dispersal, migration and the responses to anthropogenic disturbances, behavioural ecology has the potential to contribute immensely to the field of conservation. Despite the integration of behavioural ecology being initiated into conservation over 30 years ago, it is still vulnerable to criticisms such as is contained in the Caros' 1999 paper which states that "there is a conceptual divide between the study of variations in behaviour of individuals and the study of the response of populations to deterministic and stochastic events". An opinion reflected in Dr Wayne Linklaters' 2004 paper also suggests "even when behavioural ecology is applied to conservation, the difference in perspective and approach persists as a mismatch between conservation needs and research practice in behavioural ecology." A review of the key areas where knowledge of behaviour could play a role in in-situ and ex-situ conservation practises, evaluating recent contributions of behaviour ecology in conservation biology, reveals areas in which the two disciplines dovetail showing scope for behaviour ecology to contribute significantly to conservation, viewing behaviour as an integral component of overcoming conservation problems but not as the sole key to solving them ( Fiesta-bianchet & Appollino , 2003).
Population ecology seeks to quantify the number, distribution and parameters that govern a species contained within a population. The discipline of population ecology is dependent on four processes, which occur on both a global and regional scale.
(Population increase through birth rate or hatching over fixed period of time)
(Population decrease over a fixed period of time normally as a result of disease, predation or old age resulting in death)
( Population decrease through dispersal over fixed period of time)
( Population increase through dispersal over fixed period of time)
These four behavioural processes can be utilized in mathematic formulae to calculate population sizes and densities refer to figure 1.
Whilst the above referred parameters can provide a good insight into the status of populations, studies in this fashion can take a long time to achieve the desired results. Another negative factor is that the population number of individuals may not vary enough in order to correctly and accurately identify the density dependant parameters. It is also important to note that there is no underlying theory in Population Ecology on which to base predictions to population responses under new circumstances.
Nt+1 = Nt+Bt-Mt+It-Et
It is accordingly true to state that Population Ecology relies on the behavioural theories, established by Alfred Russell Wallace & Charles R Darwin who developed the theory of survival of the fittest through natural selection and evolution. Darwin's theory of evolution challenged the ordered world of design that was argued by creationists and in its place substituted Darwin's and Wallace's theory of natural selection, suggesting that environmental pressures acted on the phenotype. This occurs when the environmental pressure changes on a species population, the individuals in said population should begin to vary in phenotypic characteristics, by developing characteristics which make them more adapt and efficient in maximising their chances of survival, resulting in a higher fecundity rate, thereby making them more numerous and changing the phenotypic characteristics of a species population. These theories however are not sufficient to predict population reactions to new circumstances on their own, and it is essential to combine them with other behavioural concepts such as game theory, optimization theory, Ideal free & ideal despotic distributions, the allee effect and buffer effect.
Behavioural concepts related to conservation biology;
Assumes animals adopt behaviours which maximise their fitness, natural selection pressures act on these characteristics. Individuals displaying characteristics which maximise their fitness become more numerous as those who lack these characteristics become less numerous. This model relies on using simple animal behaviours as indicators of fitness i.e. Increased rate of feeding is assumed to increase fitness.
This model like the Optimization model assumes that animals adopt behaviours that shall maximise their fitness, however in this instance the optimal behaviour of one individual is influenced by the behaviour of other individuals.
Ideal Free Distribution
In this instance the model predicts the distribution of ideal and free competitors and invariably occurs in areas that contain varying patches of intrinsic fitness value. Ideal animals are those who know the relative rewards received by moving to patches of higher intrinsic fitness value and accordingly move freely to these patches. Free animals are able to move freely between different patches and are not constrained by factors such as dispersal or territoriality. However patches with better rewards will decrease in intrinsic fitness value as immigration increases population densities and competition.
Ideal Despotic Distribution
This model is used to predict the distribution of ideal and despotic competitors. Despotic individuals are not able to move freely between different patches within an area and are accordingly usually constrained by plants and other sessile species.
Individuals in a species are assumed to always differ. This means that individuals vary in efficiency at relevant behaviours to fitness, such as the ability to attract mates or even evading capture by predators. The Natural selection probes acts on these variations resulting in making the better adapted individuals more numerous. Individual variation is also understood to stabilize populations against changing pressures, such as when individuals develop an immunity to detrimental pathogens or parasites.
The allee effect infers that populations that are of smaller sizes and densities will have reduced survival or fecundity. Smaller populations may mean resources are low or scarce, mating may be made difficult by restricted numbers of the opposite gender or population density may be restricted by vulnerability to predators.
Assumes populations of a small size and density should occupy patches with highest intrinsic fitness value, where as larger populations should mean the majority of individuals occupy patches with lower intrinsic fitness value.
Combining Behaviour ecology & Conservation Biology
The examples detailed below outline how the combination of the aforementioned behavioural theories and rules or concepts can be combined with population ecology as a tool in the conservation of biodiversity, the principal aim of conservation biology.
Response to Human Activities and Exploitation
Human interaction and disturbance to wildlife systems will often stimulate positive or negative responses on species populations. Noise, air and light pollution can interfere with wildlife communications systems. In the Netherlands the song of male Great tits Parus major raised the minimum frequency with the increased amplitude of traffic, much the same as killer whales Orcinus area off the Washington state coast whom increased their call duration in the presence of whale watching boats (Caro 2007). In both cases it is clear that human activities have evoked compensatory responses to communication interference.
Response to land use change and Habitat fragmentation
Anthropogenic urbanization and habitat fragmentation has had a major influence and impact on the distribution and vitality of many facets of the natural world and its ecosystems. Conservationists focus on mortality and movement of species populations in response to these changing pressures. As a habitat becomes increasingly fragmented it becomes increasingly less likely that an isolated patch will become re-colonized in the case of a local extinction, an understanding of dispersal amongst individuals is key to describing population or meta-population responses to fragmentation (Sutherland 1998). Urban developments are interwoven with connecting roads which aid anthropogenic movement however come at the detriment of natural habitats. Roads cause habitat fragmentation, are a source of pollution and cause barriers to dispersal for some species. The TransCanada Highway has been made famous by its enormous wildlife over passes (50m) and underpasses (>12m), which provide corridors and facilitate dispersal. Maintenance of genetic diversity and population tolerability to change is reliant on dispersal amongst individuals between patches in the wild. Caro 2007 found that some of the large mammals such as elk Cervus elaphus, deer Odocoileus virginianus and grizzly bear Ursus arctos were found to prefer crossing the road using the over passes. Alternately cougars Puma concolor and black bears Ursus americanus preferred the relatively constricting underpasses.
Use of Corridors
Habitat fragmentation can be on as small a scale as two leaves on the same plant or as vast as forests dissected by mountain ranges. When the construct of habitat patches is such that there is no flow of individuals amongst them, then the dynamics of one region will not affect the dynamics of another region i.e. population extinction in one region does not affect extinction of that species at any other region(Sutherland 2000).Corridors can be understood as channels which allow for the flow of genetic information between patches. Habitat fragmentation is a widespread problem around the world, corridors can serve to negate impacts of roads and urban developments to natural habitats through the facilitation of migration, immigration and dispersal. Corridors can be local or global, 'Ecological principle states that a corridor should be twice the width of the average home range of the species thought to be the potential users of the corridor.' (Boyle and Ervin, 2010). Caro 2007 refers to the case of the eastern bluebirds Sialia sialis which were noted to be feeding on wax myrtle Myrica cerifera and were channelled along experimental corridors and proved a positive correlation in bluebird navigation amongst patches using corridors and tree regeneration.
Reserve design should be centred around key species for conservation, it can be generally accepted that small areas have small populations and are therefore at higher risk to extinction. Carnivores often go extinct even in very large numbers, mainly due to anthropogenic persecution along reserve perimeters, requiring reserves to be of larger extent than the home range of the species which occupy it. Wild dogs Lycaon pictus have vast home ranges, thought to have disappeared from most reserves with areas smaller than 3500Km2.Currently only a small proportion of reserves occupy such an area i.e. the Kruger National Park in South Africa extends over 18,000Km2.However in smaller reserves the 'Edge effect' has a detrimental impact on wild dog populations inhabiting protected areas, reducing their resilience against extinction(Gosling & Southerland 2000).
Captive breeding institutions began using behavioural knowledge informally during the 1980's and 1990's to design social and physical environments for the fostering of breeding species (Caro, 2007). Sutherland & Gosling (2000) suggests that an understanding of how culture is transmitted could aid re-introduction programs, criticizing previous failed reintroductions for neglecting the importance of feeding, predation and mating behaviours. The Arabian oryx gazelle Oryx leucoryx was hunted to extinction in the wild in 1972, thanks to a proactive conservation strategy which drew on a behavioural knowledge base developed from the study of a close relative to the Arabian Oryx, the fringe eared Oryx Oryx callotis, 21 pairs of successfully bred Arabian Oryx were released into the wild in Oman (Price, 1989). However Caro 1999 warns that reliance on surrogate species for behavioural research cannot be considered effective in conservation practice.
For the successful reintroduction of many species behavioural characteristics can be essential for survival in the wild. Many reintroduction attempts have failed due to the lack of basic survival skills in reintroduced populations (Sutherland 2000). Mitigating human contact in rehabilitation processes can be essential to success, as demonstrated by the feeding methods used in the regeneration of California condors Gymnogyps californianus or whooping cranes Grus Americana. California condor chicks were fed using condor head shaped puppets, discouraging chicks to associate humans with food following their release. Similarly whooping cranes were raised by humans wearing crane disguises, leading them to good feeding patches and emulating alarm calls. The results were successful, the release of both species was made easier by mitigating human imprint and the retention of natural behaviour (Caro 2007).
The proactive monitoring of populations is of significant importance to conservation and a key area in which behaviour can help extensively. Calls of illusive or secretive animals such as the corncrake Crex crex can be used to monitor population numbers and densities. Carro's 2007 paper cites a study in Tanzania of mammal species compared to highlight behavioural differences to hunting pressures. It was found that 7 out of 9 large mammal species fled more often from the observer in area's subject to higher hunting pressure. The difficulty of monitoring illegal hunting or poaching poses a serious drawback to conservation, the example of the above mentioned Tanzania study highlights the potential for behaviour ecology to provide effective shortcuts to identifying area's subject to illegal hunting pressures.
Reviewing the chronological development of behavioural ecology reveals a clear overlap with conservation biology inhibited by the pursuit of answers to theoretical questions by behavioural ecologists. Caro 2007 outlines seven steps to refining more relevant and effective studies of behaviour to the field of conservation. Behavioural ecologists should begin by designing studies around conservation problems, communicating with conservationists and assuring relevance to conservation. Work should be carried out in threatened or disturbed habitats, ensuring work is relevant to conservation. Research projects should include a wide variety of the taxonomies relevant to the region of study, maximising the potential of understanding as many of the variables as possible associated with restoration projects. Research projects most likely to be supported publicly and politically are those which concentrate on high profile species. Whilst study of the fringe eared Oryx was successful in helping with the Arabian Oryx restoration project, it is suggested that the use of surrogate species be avoided as even closely related species can differ markedly in behavioural characteristics. Research findings and material should be relayed to wildlife managers rapidly for effect, pursuits of scientific notoriety in the form of academic journal publications should come second to the need for rapid sharing of information to conservation managers on the ground. In order to gain public appeal and for informed decision making it is integral that work carried out by behaviour ecologists be popularized through public speaking, newspaper articles and popular forms of media. The role of behavioural ecologists must not be blown out of proportion but must be emphasized for its importance to the overarching aim of conservation, the conservation of biodiversity. Sutherland 1998 reminds us "we have a moral obligation" to carrying out relevant behavioural studies and to contributing those findings to the conservation of biodiversity.