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1 Introduction This manual deals with methods and techniques applicable under field conditions often remote from the usual support facilities characteristics of this last quarter of the twentieth century. Alter- nating electric current, with constant voltage, is not readily avail- able in areas that require the study of vertebrate ecology, espec- ially in remote areas where a faunal survey must precede the establishment of a park or reserve. Thus, the technological sup- port for faunal surveys normal for more settled regions is often lacking and one must fall back on techniques that to a large ex- tent have been forgotten by biologists in recent decades. The compass, notebook, india ink pen, watch, scales, binoculars, and tape measure are still the basic tools, augmented by calipers, pliers, wire, camera, formalin for preservation of specimens, and tape or tags for marking trees (see Figure 1.1). This manual outlines the basic steps for conducting prelimi- nary studies of mammalian ecology. Several indirect census methods are available for studying large terrestrial herbivores; they are suitable for rapidly making rough comparisons of activ- 1
TECHNIQUES IN PRIMATE POPULATION ECOLOGY FIGURE 1-1 Typical collection of field equipment for undertaking primate rpnsusino censusing ity levels in large areas. Thus, fecal pellets, dung piles, and ani- mal tracks can aid in estimating the abundance of a species being studied. Indirect methods have also been used to determine age classes and ranging patterns in some large terrestrial species and have been valuable additions to direct observational techniques. Although observers should be aware of the value of using signs of activity to locate primates, no standardized methods are avail-
Introduction 3 able that allow extrapolations from the abundance of feces around sleeping and resting trees, or from the amount of vegeta- tive matter (fruits, leaves, petioles) dropped around feeding trees, to the number or species of primates that have progressed through an area. There are other situations in which extrapola- tion is a satisfactory censusing procedure. One is estimating the number of pygmy marmosets in an area by counting trees that have sap holes; another is estimating the baboon population by counting rock-cliff sleeping sites. The censusing of arboreal species, including most primates, continues to rely on standard- ized and relatively time-consuming visual counts of individual animals by observers. The objectives of various types of censuses are stated later in this introduction. Chapter 2 discusses the selection of survey sites, and Chapter 3 is concerned with methods for identifying and describing characteristics of habitats that are essential to support the target species. It is seldom possible to count all members of an animal popula- tion directly. Consequently, sampling methods must be used. Al- though typically social and diurnal, most primate species live in tropical forests where visibility is poor and movement by the ob- server is often impeded. Chapter 4 describes sampling techniques most useful for counting primates, emphasizing forest species because forested habitats contain the greatest number of species and pose the greatest number of practical problems. The sampling method selected will depend on the objectives of the study; the characteristics of the study species; the habitat; and the availability of time, money, and personnel. Objectives often involve one or more of the following: â¢ Determining the presence (and abundance) or absence of particular species in relation to geographic and habitat features. â¢ Estimating densities of animal and plant populations. â¢ Compiling data on group sizes and the age and sex composi- tions of populations. â¢ Determining population trends. â¢ Determining microhabitat preferences of study species. â¢ Determining interspecific associations.
4 TECHNIQUES IN PRIMATE POPULATION ECOLOGY These objectives are fundamental to the development of conserva- tion and management programs, as well as to the understanding of the biology of the populations and ecosystems concerned. Three techniques for estimating population densities are dis- cussed in this report: broad surveys, line transects, and detailed study of specific groups. Broad surveys are used as pilot studies in order to' assess land uses, inventory species, and compare the status of populations in large areas in a relatively short period (Eisenberg, 1979; Scott et al., 1976b). The method best suited for obtaining data on the relative num- bers of primate groups in forest habitats is the random compass line transect. Because of its statistical reliability, this method pro- vides estimates that can be used for general management of species. The most accurate method of estimating primate densities is the detailed study of specific groups. This method provides data on home range size, group size, and age-sex composition over time, and it provides a basis for intense species management and hypothesis testing. Accurate estimates of the composition and use of space by a population are necessary before trends in population size can be understood. Therefore, techniques for aging and sexing primates are given in Chapter 5 and are followed by methods for evaluating habitat use in Chapter 6. Collecting data on the use of space, feeding habits, and time budgets is the most time-consuming part of observational studies. The use of life tables for the analysis of populations is described in Chapter 7. Finally, environmental and other factors influencing population size are discussed in Chapter 8.