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2 Site Selection MAPS AND PHOTOGRAPHS Although most of the earth's surface has been mapped by foot survey, aerial photography, or satellite imagery, information on the distribution of vegetative cover in some tropical countries is not well documented. Thus, when working in a new area it may be necessary to spend time determining where the censuses should be made. If topographic maps are available, they provide the logical starting point. Working from the best published map you can ac- quire, you should find the approximate position of the area you intend to survey. Typically, your starting point will be some major geographic feature (e.g., lake, river, mountain range). You may find that a map has a scale that is too large to include features such as tributaries, lagoons, hills, and outcroppings, which would be perfectly obvious to you on the ground. It is important to examine vegetation maps, which enable you to become familiar with the range of habitats that can be ex- pected in the survey region. Broad classifications are available for 5
6 TECHNIQUES IN PRIMATE POPULATION ECOLOGY the neotropics in Holdridge (1967), for Asia in Puri (1960) and Richards (1966), and for Africa in Keay (1959). If recent aerial photographs are available, they will augment the maps and provide details on the status of vegetation at poten- tial survey sites. Such an analysis is cheaper than making an aerial reconnaissance in a small plane. Selecting a site can also be accomplished by ground travel, though this method is more time- consuming than the others. In areas for which detailed maps and photos are not available, it may be necessary to expand the scale of the preliminary mapping efforts described in Chapter 4 for es- tablishing grids. Images from LANDSAT satellites are being used increasingly for developing regional and national inventories of land-use patterns and for monitoring changes in vegetation. The large scale of the images makes them useful in selecting forested sites for surveys. Detailed interpretation of satellite photos depends on ground ver- ification or on classification of vegetation types based on visits to the sites. Potential applications of satellite imagery techniques for the analysis of vegetation are discussed in Chapter 3. FAUNAL LISTS AND FLORAL INVENTORIES Most major geographic areas have at least provisional faunal lists for the major vertebrate classes. Before undertaking a survey in a new area, you should make a provisional key based on published reports and museum specimens. Since many areas that you may wish to survey have strict regulations concerning specimen collec- tion, the key must utilize field characters that are readily identi- fied in an intact, living specimen. Of course, on occasion, it is necessary to collect and preserve voucher specimens (Chapter 3). The following field key for the primates of Guyana should suffice as an example: KEY TO THE ADULT PRIMATES OF GUYANA 1. Size small (< 1 kg) and squirrel-like; tail bicolored 2 1' Size medium to large; tail color uniform 3 2. Face and body dark, with hands and feet reddish; tail reddish proximally, black distally Saguinus midas
Site Selection 7 2' Contrasting black muzzle and light body; tail like legs and body golden brown, proximally with black tip Saimirisciureus 3. Basic body coloration black 4 3' Body coloration brown, gray, or reddish 6 4. Large body size (> 6 kg); prehensile tail Ateles paniscus 4' Medium body size ( ~ 1.5 kg); nonprehensile, bushy tail 5 5. Contrasting white fur on face; body pelage long Pithecia pithecia cr 5' Typical body hair length; face dark and not contrasting to body color; conspicuous beard (cr) Chiropotes sutanus 6. Tail bushy and nonprehensile; basic body color gray to agouti brown Pithecia pithecia 9 6' Tail partially or fully prehensile 7 7. Basic adult body coloration reddish; conspicuous beard Alouana seniculus T Basic body coloration light brown or brown 8 8. Conspicuous flat-topped black cap with tufts on head Cebus apella 8' Buff to brown cap; basic body coloration gray-brown Cebus nigrivittatus SPECIAL STUDIES OF INDICATOR SPECIES A general knowledge of natural history is invaluable during initial attempts to characterize forests. Parameters of habitat quality, such as age of the forest, relative density of fruiting trees, and persistence of standing water, can often be assessed by keeping careful notes on other vertebrates present in the forest. Birds are conspicuous by their diurnal activity, voice, and often brilliant coloration. When you are transect walking, birds are often the most frequently encountered vertebrates. You can often make general statements by noting the frequency of bird sightings and the species identity. Consider the case where primates are rare in, or absent from, a forest block. If one has noted that large frugivo- rous birds, such as hornbills (in Asia), are present, there is reason to suppose that the lack of primates is not tied to a lack of fruiting trees. A knowledge of frog calls can often aid in the assessment of the availability of standing water. Amphibians often have strict limits on their tolerance for aridity and temperature minima. Trees may be useful as indicators of habitat quality. Certain trees are of pivotal importance in primate feeding (e.g., Ficus), and the presence or absence of fig species may correlate with the relative abundance of primates. Some species of trees are indica- tors of soil type or drainage patterns. For example, well-drained
8 TECHNIQUES IN PRIMATE POPULATION ECOLOGY soils in northern South America are typified by Saman. Pithecol- obium, whereas poorly drained soil may be dominated by ma- ne he palm, Copernicia. The presence of various rodents may also indicate the quality and disturbance of forest habitats. Muul and Lim (1978) described the association of Malaysian flying squirrels with forest type. They showed that 4 of 11 species of frying squirrels occur in pri- mary and partially cut forests; another 5 species occur in dis- turbed forests, which range from secondary forests to mixed fruit and rubber plantations; the other 2 species occur frequently in both primary and secondary forests, but rarely in plantation areas. Similar correlations between habitat and species should be discernible for diurnally active mammals and birds. An aware- ness of such correlations will provide additional insight into un- derstanding the community in which any censused species occurs. During long-term studies, it is of great value to combine several projects at the same study site. Interchanges between workers who have concentrated on such diverse aspects of vertebrate ecology as bird feeding, amphibian reproduction, and rodent population dynamics often lead to the development of exciting new ap- proaches in data acquisition and analysis. Many mechanisms of population biology- are understood only for a few nonprimates. Indeed, rodents can be studied with great profit to aid our under- standing of how tropical ecosystems function. Rodent populations have been of interest to mammalian ecolo- gists for many decades, particularly in temperate latitudes. There are several reasons why rodents and their population dynamics should be of interest to ecologists. First, rodents are common members of virtually all terrestrial ecosystems, where they play an important rote as "key industry" animals in the transfer of energy from primary producers (plants) to secondary consumers. Sec- ond, rodents can have a considerable economic impact on human food supplies, particularly in tropical countries, where their destruction of crops and stored grain can run into millions of dollars annually. Crop destruction by rodents and insects may be many times greater than that caused by primates and birds. Third, various rodent populations serve as reservoirs for a diverse array of disease organisms that pose direct health threats to man. Plague, scrub typhus, Lassa fever, and various types of encephalitis
Site Selection 9 and hemorrhagic fever are just a few examples of rodent-borne diseases that can affect the health of human beings and non- human primates. Finally, because they are ubiquitous and rela- tively easily studied, rodents and their populations can be used as "model systems" for studying the adaptive strategies of mammals in a wide variety of environments. Results of studies aimed at determining the basic operation of rodent populations under dif- ferent environmental conditions have a direct bearing on our theoretical understanding of the evolution and maintenance of natural ecosystems.