10 - Mammals
Published online by Cambridge University Press: 05 September 2012
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Summary
Introduction
Census methods for mammals depend critically on the size of the species and its natural history. If species are diurnal, common and highly visible, the census problem is relatively simple. If species are nocturnal, rare and difficult to detect, the census problems are most difficult. As in all ecological census work, you need to decide the purpose of the study and the level of precision you require. Higher precision bears costs in time and money, and methods that lead to higher precision might not be practical for some species within a finite budget.
A sequence of decisions to facilitate the choice of methods for a mammal census is outlined in Figure 10.1 (Table 10.1). Just because many studies of a particular species or group of species have used a particular method does not mean that you must use this method for your study. Many studies have not used the best methods in the past, and there is no reason to continue using sub-optimal techniques that waste time and money.
Total counts
The simplest way to determine how many individuals of a particular species of mammal live in an area is to count all of them. This census method we might consider the Holy Grail of mammal-census methods, yet it can hardly ever be achieved. Total counts can be done on large mammals in restricted areas (Bookhout 1994), but one should always be sceptical of the accuracy of total counts, since in most cases to date there is a negative bias – estimated numbers are less than actual numbers.
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- Ecological Census TechniquesA Handbook, pp. 351 - 369Publisher: Cambridge University PressPrint publication year: 2006
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