Putman R.,Keil House |
Flueck W.T.,University of Basel |
Flueck W.T.,Atlántida Argentina University
Animal Production Science | Year: 2011
It has been noted that the search for patterns in biology to assist our understanding, often leads to over-simplification. That is, we are satisfied with statements that 'the species as a rule does this' or, 'males of this species do that'. But within such generalisations are masked what are often important variations from that supposed norm and in practice there is tremendous variation in morphology, physiology, social organisation and behaviour of any one species. The focus on a supposedly mean optimal phenotype has diverted attention away from variation around that mean, which is regularly regarded as a kind of 'noise' stemming merely from stochastic effects, and thus irrelevant to evolution. Yet it is becoming increasingly clear that this variation is by converse extremely significant and of tremendous importance both to evolutionary biologists and to managers. Such intraspecific variation (IV) may be directly due to underlying genetic differences between individuals or populations within a species, but equally may include a degree of phenotypic plasticity whether as 'non-labile', traits which are expressed once in an individual's lifetime, as fixed characteristics inherited from the parents or as more labile traits which are expressed repeatedly and reversibly in a mature individual according to prevailing conditions. Recognition of the extraordinary degree of IV which may be recorded within species has important consequences for management of cervids and conservation of threatened species. We review the extent of IV in diet, in morphology, mature bodyweight, reproductive physiology, in population demography and structure (sex ratio, fecundity, frequency of reproduction) before also reviewing the striking variation to be observed in behaviour: differences between individuals or populations in ranging behaviour, migratory tendency, differences in social and sexual organisation. In each case we explore the factors which may underlie the variation observed, considering the extent to which variation described has a primarily genetic basis or is a more plastic response to more immediate social and ecological cues. © 2011 CSIRO.
Putman R.,Keil House |
Watson P.,Brynkinalt Business Center |
Mammal Review | Year: 2011
Population density alone is unlikely to be a good predictor of the impacts of deer on their environment. The assessment of management requirements should therefore be based on assessment of deer impacts, alongside estimates of density. Both density and impacts need to be monitored at a landscape scale, and there is a need to develop appropriate methodologies that allow managers to consider the current and likely future impact of deer. The relevant scale for assessment (and management) varies both with deer species and context of impact, but should always encompass at least the estimated biological range of the population of deer present in an area. Some impacts (e.g. deer-vehicle collisions, and risks of disease transmission) may need to be assessed at a wider regional level. In this review we consider various approaches available for assessing: absolute or relative animal abundance; impacts of ungulates on agriculture, forestry, amenity woodlands and other conservation sites; impacts on public safety (e.g. through road traffic accidents) and on humans or livestock through potential spread of disease. In each case the advantages and disadvantages of a variety of methods are considered, before recommendations are made for methodologies which are sufficiently accurate, sufficiently robust and sufficiently practical to be favoured in a management context. To address impacts at the landscape scale requires management policies that integrate information on both positive and negative impacts of deer in order to ensure appropriate and holistic management. We present a decision-support framework suitable for use within the UK, using inputs from a variety of possible impact types to assist managers and forewarn of situations where current management may need to be modified. © 2011 The Authors. Mammal Review © 2011 Mammal Society.
Putman R.,Keil House |
Langbein J.,Greenleas |
Green P.,South Woolley Farm |
Watson P.,Brynkinalt Business Center
Mammal Review | Year: 2011
At high densities, deer populations may have adverse effects upon and within their environment. In this review we explore published and unpublished information to derive density thresholds for deer species in relation to impacts upon agriculture, forestry, conservation habitats, road traffic, and human and livestock health in the UK. Impact levels are affected by many factors other than absolute density. We therefore seek to establish the range of densities within which negative impacts might start to occur and which should trigger objective monitoring of actual impacts. In commercial forestry, a threshold of 4 deer per 100ha has been suggested. Unfenced native woodlands seem to regenerate naturally if there are fewer than 4-5 large deer or fewer than 25 roe deer Capreolus capreolus per 100ha; open habitats may suffer only light or moderate impacts from red deer Cervus elaphus at landscape densities of 7-8 per 100ha. Woodland bird species may have declined where deer densities are high but absolute thresholds seem impossible to establish. One study suggests maximum diversity at about 8 white-tailed deer Odocoileus virginianus per 100ha. Deer-vehicle collisions are affected by various factors in addition to deer density, but British and American studies suggest that accident frequencies decline at densities below 7-8 per 100ha. Fallow deer Dama dama populations may maintain bovine TB (bTB) infection at much lower densities (25/100ha) than red or roe deer (91/100ha and 200/100ha, respectively) assuming 100% prevalence. Even at 30% prevalence a density of 75 fallow deer per 100ha could maintain bTB within the population. We conclude that deer density alone is unlikely to be a good predictor of impact, and suggest that long-term management should be based on assessment both of actual impacts and apparent density of deer. © 2011 The Authors. Mammal Review © 2011 Mammal Society.
Putman R.J.,Keil House
European Journal of Wildlife Research | Year: 2012
For many of those wildlife species with larger home ranges, the expressed annual range size may extend over many landscape units and separate landholdings. In order to be wholly effective, management of such a population for control of numbers or in mitigation of negative impacts needs to be coordinated at the landscape scale rather than the level of individual properties. By corollary, differences in management of a population in different parts of the biological range (differences in intensity or objective of management) may have significant effects on numbers and distribution across the wider landscape. Thus, management in one part of their range towards one objective may compromise the ability of managers of the same population in another part of the range, to deliver their, perhaps different, objectives. This paper offers demonstration of such landscape level effects of differential intensity of culling, focusing on open hill populations of red deer (Cervus elaphus) in Scotland. On each landholding within the wider catchment, mismatch between observed counts in a given year and population size and composition predicted from counts of previous years (on the basis of known 'domestic' rates of recruitment and known culls) permits identification of possible episodes of active immigration onto or emigration from that particular property/landholding. Coincidence in time of episodes of presumed immigration or emigration from adjoining land units may be used to infer movements of population between those landholdings and identify sources and sinks within the population's wider home range. © 2012 Springer-Verlag.