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3 Habitat Description and Specimen Collection Accurate and standardized ecological information should be mandatory for any census or survey. A description of the physical features, community structure, and vegetation in a survey area is a necessary prerequisite for comparing densities of censused ani- mals in different areas or in different habitats in the same area. The more detailed the habitat description, the more useful the census results. It is necessary to emphasize that habitat descriptions can be either highly quantitative or just qualitative without very much field measurement. The type of data, as discussed for census pro- cedures, will depend on the length of time available to conduct the survey, the personnel involved, and the level of sophistication desired. The methods for collecting habitat information should be decided when the census is planned. If a small area is to be surveyed, attention can probably be di- rected toward microhabitat differences, such as flat terrain, hilly terrain, and flooded or unflooded areas. However, conducting a survey in larger areas will not permit attention to such detail, and 10
Habitat Description and Specimen Collection 11 it is advisable to evaluate habitat types in relation to the way cen- sus transects have been selected (see Table 3-1). Ecological communities are frequently obvious to the researcher while conducting a census. For example, moist soil in a forest along a river indicates flooding. In a montane forestr if sampling covers a wide range of elevation, describe the habitat at every 50 m of elevation. Forests that have been logged or show signs of re- cent regeneration will require descriptions separate from those for undisturbed forest. Often, broad ecological communities are not apparent in the census zone, and the researcher may decide to describe the habitat at noticeable changes or every hour along the transect census. Whatever the choice, standardized descriptions of the habitat must be an integral part of the census. HABITAT PROFILE A physiognomic or structural classification of habitat types sepa- rates vegetation according to height and interdispersion of height classes. A sketch of a vegetation profile along transect lines has proved to be useful in augmenting detailed notes. Composite hab- itat profiles for an entire study area have also been useful in sum- marizing the relationship between animal abundance (based on sightings or signs) and habitat type (Figure 3-1). In Sri Lanka, vegetation was classified into three major classes: (g) grass (and forbs), (Sc) scrub, and (T) trees. Mixtures of the three classes were indicated by the symbols (g, Sc), (Sc, T), (g, T), and so on. By use of transect sampling, it was possible to esti- mate the relative proportion of vegetation classes for the study areas (Figure 3-2). Scrub was arbitrarily defined as being com- posed of woody plants less than 2 m in height (Eisenberg and Lockhart, 1972). In adapting this scheme to other areas (e.g., the neotropics), the researcher should designate special vegetation categories, such as the palm (Copernicia) and savanna or tree savanna composed of Pithecolobium, Acacia, and grasses. A habitat profile data sheet may help standardize observations by blocking out the habitat characteristics according to a scale that ranks the abundance of the feature from absent to rare, moderate, or dense. Undergrowth, epiphyte load, and foliage cover may be rated in this way. Information on such features as
12 TECHNIQUES IN PRIMATE POPULATION ECOLOGY TABLE 3-1 Estimates of Time Required for Field Work by Two Persons" Type of Work Area (km2) Days Habitat survey General description 1 2 10 10 Quantitative description* 1 8 Density estimates (censusing) 10 60 Crude Transect 1 6 10 10 20 20 Quadrat 1 6 10 14 Ecological 20 40 Transect 1 6 10 30 20 40 Quadrat 1 6 10 30 20 60 "Does not include travel time to study areas; assumes work on foot; as- sumes forested habitat and some trail construction; assumes some fa- miliarity with identification of flora and fauna. *Nonpermanent grid. the number of layers (shrubs, understory, main canopy, emer- gents), the light penetration through the canopy, the clumping of trees, and the presence of buttressed trees may also be listed. A visibility or obscurity score may be useful in comparing ease of observing primates between habitats. This may be as simple as ranking visibility as excellent, fair, or poor, but a better proce- dure is to place a 5- or 10-m striped stick at standard distances (10 m, 20 m, or more) from the transect path and determine the percentage of the stick that is obscured by the vegetation. A stick can easily be prepared by painting on it conspicuous stripes 1 m apart.
Habitat Description and Specimen Collection 13 CHARACTERISTICS OF HABITATS WATER AND DRAINAGE The presence of water bodies, such as streams, lakes, ponds, and swamps, requires notation and brief description. Areas that re- tain standing water for prolonged periods, such as ponds and swamps, may also show unique vegetative characteristics requir- ing separate habitat profile descriptions. Water drainage and quality may be indicated by characterizing a stream or river on the basis of color. Three major categories used in the Amazon basin are "white," "black," and "clear" and are important with respect to trace elements and suspended nutrients (Fittkau et a/., 1975; Soili, 1975). The color of a stream or river is not necessarily indicative of the soil and vegetation characteristics immediately adjacent to it. The color tells something about the dominant soil and vegetation in the major watershed feeding the river. The pH can be checked quickly with litmus paper (Table 3-2). Current evidence suggests that black-and clear-water drain- o Presbytis cristotq Relative abundance: o low o intermediate â¢ high FIGURE 3-1 Primate abundance as a function of habitat type. A composite physiognomic habitat profile is a rapid way of summarizing which habitats sup- port which species and whether all areas of available habitat are being exploited. The relative abundance of two primate species is shown for nine habitats in Java. Indonesia: 1. open sand; 2. Barringtonia, mangrove and tropical swamp forest; 3. alluvial forest; 4. plantations of coffee and rubber; 5. streambed vegetation; 6. bamboo//i'cÂ«s; 7. tropical rain forest; 8. transitional forest; and 9. bamboo/ grass. Redrawn from Seidensticker and Suyono, 1980.
14 TECHNIQUES IN PRIMATE POPULATION ECOLOGY Transect line Station No. Vegetation Type Herbaceous Cover Animal sightings (or signs) 1 g 90% Elephant feces 2 g 80% â 3 g 60Â°/o â 4 g 50% â 5 Sc 50% â 6 Sc 30% Axis deer (l) 7 Sc 40% â 8 Sc,T 20 % â 9 T < 10% â 10 T < 10% Langur Monkey (2) FIGURE 3-2 Preliminary transect sample of vegetation types in a survey area.
Habitat Description and Specimen Collection 15 age areas have lower productivity than white-water areas. Black water may be caused by tannins and other compounds of plant decay as well as by eroded material. SOIL TYPES Soil science is an extremely specialized and important discipline, and in a survey of a new region only the most superficial notes can be taken; yet even brief descriptions can be of considerable value. In a first-order description, soils are classified on the basis of color and particle size. Most nutrients generally occur in the humus and upper soil layers, which may be only centimeters in thickness. Soils are generally layered over bedrock, which varies in chemical composition. If a road has been cut through a hillside or if a natural landslide has exposed a "profile," a sketch or photograph with a scale can clarify soil depth, layers, and geolog- ical substrate. Color, depth, and layering are elementary data (Figure 3-3). In addition, some note should be made of the rela- tive particle size. Claylike soils have extremely small particles and when dried out will harden and often crack with a characteristic hexagonal pattern. Sandy soils with intermediate particle size rarely show the reduced porosity when drying that claylike soils do. The presence of pebbles or rocks is important in understand- ing the nature of the overlying vegetational cover. Indeed, the whole rooting pattern and subsequent vegetational cover result from an interplay of soil type and duration of groundwater or moisture in the soil. VEGETATION Beyond a characterization of the habitat based on physiognomic features and a list of the common dominant plants, it is necessary to relate species composition to different forms of topography, drainage, and soil type. The frequency and dominance of species can be determined by using plotless or plot methods (Pandeya et al., 1968). The field worker need not be an expert botanist to compile quantitative floral data; however, in more detailed ecological studies, it is important to be familiar with the names of the com-
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Habitat Description and Specimen Collection 17 Top soil Loleritic hordpan - Sedimentary rock - Metomorphic rock FIGURE 3-3 Profile of soils and underlying rocks. mon dominant plants in the area. Common names are useful but in a final description Latin binomials should be given. It may be necessary to make a collection of each plant species, including leaves, flowers, and fruits, and then seek aid from a forestry offi- cial or botanist at a local museum. Equipment and materials use- ful for descriptions of vegetation include a tape measure, sur- veyor's tape, stakes, tree tags, paints, compass, and knife. Three measurements are especially useful in preliminary stud- ies of vegetation. These are the trunk diameter at breast height (dbh), tree height, and crown volume. Regardless of the vegeta- tive sampling technique used, all trees above a dbh of 12 cm are usually identified. The measurement of dbh is useful in determin- ing the maturity of a forest. Crown volume is an important mea- sure of potential productivity if one is estimating the production of fruit or leaf crops. The dbh is positively correlated with the height of a tree within a given species and is the easier of the two size variables to measure. Either a standard tape or a forester's tape may be used to de-
18 TECHNIQUES IN PRIMATE POPULATION ECOLOGY termine the tree diameter. The circumference obtained in using a standard tape is divided by ir = 3.14 to record the diameter. One scale on a forester's tape shows the diameter directly. Heights are visually estimated to the nearest meter. Tree height can be mea- sured with a range finder, but pacing distances and angular mea- surements suffice in a preliminary description (Figure 3-4). Crown volume is estimated with two pieces of information: the diameter of the crown and the general shape of the crown. Crown diameter may be determined by pacing and the shape by deciding whether the crown is best represented as a sphere, hemisphere, or some other shape (Figure 3-5). By dividing the crown diameter by 2 to obtain the radius, the volume of spherical canopies can be calculated from the equation V = 4/3 TT r3. This volume is then divided by a fraction determined from inspection of the whole crown and determination of its approximation to a theoretical sphere (Figure 3-5). Cover is the space occupied by all the individuals of a species or physiognomic class of vegetation. It is usually expressed as a per- centage. Two types of cover are usually measured: canopy cover and ground cover. Canopy cover expresses the degree of closure or shading by adjacent trees. In a closed canopy where all crowns ton Â°* * h/d height = h + 2 m h â Z m Paced distance (d) FIGURE 3-4 Measurement of tree height and diameter at breast height (dbh). Trigonometry is used to estimate the height of a tree from measurements of one angle and one leg of the triangle.
Habitat Description and Specimen Collection 19 CROWN VOLUME = 4/3TT (D./2)3 - Assumed hgmisphi - V = 1/2C4/3*TT(D?/2)]3 FIGURE 3-5 Measurement of tree crown volume. The volume of a tree crown may be estimated as that geometric shape that most closely approximates its shape, usually a sphere or hemisphere. The formulas for the volume (V) of a sphere and hemisphere require an estimate of the diameter (D,, D2) of the crown; TT Â«= 3.14. touch, the cover is 100%. Ground cover is estimated by sampling an arbitrary area (1 m2) and estimating the amount of soil exposed. This is a useful measure in savanna habitats. In estimating ground cover a rating scale may be developed. For example, if one were estimating the amount of herbaceous plant growth within a 1-m quadrat, it could be expressed as 60%, 20%, or some other percentage. Usually one establishes a series of cover classes: one series for 0-24%, two for 25-49%, three for 50-74%, and four for 75-100%. For ground cover, a 1-m2 area should be sampled at each 10-m interval. Three methods frequently used to characterize vegetation are the strip, quadrat, and quadrant methods. Strip Method The strip method of vegetation analysis is commonly used by for- esters and variations are used by primatologists (Dittus, 1977b; Struhsaker, 1976). This method is convenient because the vegeta- tion sample strips are run along the animal census transect and are reliable samples of habitats (see Chapter 4). The analysis usu- ally includes descriptions of trees and estimates of cover. One problem is how much of the censused habitat should be
20 TECHNIQUES IN PRIMATE POPULATION ECOLOGY vegetatively analyzed. Foresters using the strip method regularly sample 10%, but Struhsaker (1975) found that a sample repre- senting about 3% of the home range of his main study group was adequate to characterize the forest composition. Two procedures may be followed if a transect already exists. One is to sample all trees within a fixed distance of each side of the transect (5 m would be acceptable). However, sampling a transect longer than 3 km in this way would be difficult unless the observer had plenty of time. Therefore, where longer transects ex- ist or there is considerable variation in vegetation, it is best to es- tablish a sample swath every 100 m. Swaths 10 m wide are made through the study area. Quadrat Method The term "quadrat" generally refers to a sample area of a given shape and size used for analysis within a community. Sample plots should reflect the range of habitat types under study. By placing each sample plot at random within the study area, the data will be representative of the plant community as a whole. For example, if the area under study is divided into a grid and the plot squares are numbered consecutively, a table of random num- bers can be used to select a sample of 10 from a grid of 100 squares. A variation of this method is to divide the community into a series of rectangular plots and then sample at random within each of them. The total area of plots will not cover the entire com- munity to be studied and may often be arranged in strips so that a certain proportion of the community is analyzed. In this way, one usually attempts to sample 5 or 10% of the total habitat. The number of quadrats used depends on the variation within the vegetation and the degree of accuracy required. As a rule of thumb, it is far better to analyze many smaller quadrats than a few large ones in a community. The "grain" of the analysis is im- portant. If one is studying a community of small plant species, a quadrat may be as small as 1 m square. But larger quadrats are required in a study of tree distribution. For a discussion of quad- rat sampling applied to sampling primate populations, see "Quad- rat Censuses" in Chapter 4.
Habitat Description and Specimen Collection 21 In a preliminary analysis, when all quadrats have been sam- pled, the number of times each species was present in each quad- rat is tabulated. This figure is then divided by the total number of quadrats sampled to give the observed frequency of each species. This value is often expressed as a decimal or a percentage. Find- ing the frequency of occurrence is a quick way to determine rela- tive composition over a wide area. The density of a given plant species is expressed as the number of individuals of that species per selected unit area. It is one of the best measurements for a precise description of habitat. The num- ber of individuals of each species in each quadrat is recorded and the average number per quadrat is then calculated. Quadrant Method In the analysis of tree communities, plotless sampling is frequently employed. This technique, which may be carried out rapidly, is called the quadrant method. Basically, one establishes a series of transect lines running in a given compass direction (e.g., north- south or east-west). Referring to a table of random numbers, one measures random distances along these lines, thus locating a series of random points. From each of these random points, one draws an imaginary line perpendicular to the transect line and thus establishes four quadrants. Next one measures the distance to the nearest tree or to the nearest tree of selected species in each of the quadrants. In general, the aim is to identify the species, measure the distance from the sample point to the nearest tree, and record the dbh and the area of ground covered by the base of trees. In any transect sampling of this nature, the worker must es- tablish at least 100 points that yield measurements for 400 trees. After completion of the sampling, analysis can be made on the basis of individual species or for the set of trees as a whole. One can calculate the mean distance (3) of trees or species from the point by summing all distances (d) and dividing the total by the number (n) of distances measured. The equation becomes d = d/n. One can convert the plotless method into a grid for calculating the density of a species by treating the distance from the random point to the nearest tree as the hypotenuse of a right triangle or as
22 TECHNIQUES IN PRIMATE POPULATION ECOLOGY the diagonal of a rectangle that is twice the size of the triangle. The density is calculated as the reciprocal of the mean distance squared times a reference area to convert the densities to a uni- form area (e.g., individuals per hectare). Thus, for species A, whose mean distance between the random points and the nearest trees is 4 m, the density = l/d2 (1002) or 1/16 (10,000) = 625 trees/hectare of species A. Figure 3-6 portrays the quadrant method. The relative density and relative dominance of different tree species can be calculated after the basal area of the trees and their densities are known. The relative density = number of individuals of a species number of individuals of all species X 100 The relative dominance = total basal area of a species total basal area of all species X 100 a) b) I QO O o Oo n nÂ°Â°0 0 o * ) o Â°\ o O*' Â°0 0 o O 0 o On FIGURE 3-6 Plotless quadrant method for estimating relative tree densities. Random points are set along the vertical transect line. A perpendicular line is then drawn dividing the area into four quadrants, I, II, III, IV, that are numbered clockwise, (a) The distance (arrow) is measured from the random point to the nearest tree in each quadrant when an estimate of the relative density of all trees of a minimum dbh is desired, (b) The distances to specific tree species (solid and open dots) are measured when an estimate of the relative density of different species (in a two-species community) is desired. Adapted from Phillips, 1959.
Habitat Description and Specimen Collection 23 OTHER INFORMATION Certain other information pertaining to the status of the habitat, such as hunting and trapping pressure and history of land use, is important. This information is acquired by interviewing local in- habitants and government officials and consulting published rec- ords. The kind and degree of human influence in the habitat is evaluated by evidence of disturbance. Such evidence includes human settlements and agricultural and lumbering activities. This information is especially important for evaluating the pres- ent and future status of primate populations. (See Neville et al. (1976). An unpublished report by K. M. Green is also useful; to borrow a copy, write to K. M. Green, National Zoological Park, Washington, D.C. 20008.) Photographs of the vegetation along the transect and several meters off the transect in the vegetation are useful. Black and white film is sufficient, but color film will provide more detail. SPECIES MAPS The preparation of species maps of large trees is a method for recording resource distribution. Mapping large areas of the study site or census zone is not always possible. Nonetheless, smaller vegetative sample plots or shorter transects will provide data from which rudimentary, but useful, profiles of habitats or forests can be prepared (Figure 3-1). In study sites without existing transects, or if the researcher desires to sample larger areas, a compass and measuring tape are the basic tools to be used. Random directions are selected and followed with a compass and, by using a measuring tape or by pacing along a straight line, the desired distance is established. Surveyor's tape, blazes, or stakes can be used to mark the vegeta- tion sample plots. For permanent identification of individual trees (which can be useful for future studies of phenology, succes- sion, and animal resource utilization patterns), aluminum tree tags, numbered blazes, or paint are used. This permanent identi- fication of each tree is mandatory to develop a vegetation map for long-term ecological studies. For an example of an elaborate veg- etation map, see Figure 3-7.
24 TECHNIQUES IN PRIMATE POPULATION ECOLOGY FIGURE 3-7 Species vegetation map with projected physiognomic vegetation profile. Vertical structure of the rain forest in Gabon along a portion of transect 90 X 5 m. Trunks shown by dotted lines are outside the transect width but sup- port crowns included in the section. The horizontal structure is shown by the pro- jection of the canopies and trunks in a wider sample area of 90 X 10 m. Canopies with lianas are represented by hatched areas on the profile. Identifications of tree species may also be labeled in these illustrations. Redrawn from Hladik, 1978. Many study areas require vegetative analysis of shrub or grass in addition to the taller trees. This is particularly true for sa- vanna-dwelling terrestrial primates in Africa and some Asian Colobinae and Cercopithecinae. For example, Dittus (1977b) an- alyzed shrub associations in Sri Lanka. Struhsaker (1975) found that the strip-enumeration method is preferable for estimating the density of particular species in a large study area. He also found that, because of the aggregated
Habitat Description and Specimen Collection 25 dispersion pattern of many forest species, the quadrat method is better for evaluating densities in a local part of the forest, such as the home range of a group. In Struhsaker's strip method, all trees within 2.5 m of the trail and 10 m or more in height were identi- fied; the taller trees were identified because the leaf-eating mon- keys he was studying fed in those trees. Data from several strips through the home range of his red colobus study group were summed to obtain a strip that exceeded 2,800 m in length and 5 m in width. This strip corresponded to a sample area of 1.4 ha, with 469 trees and 51 species. The diversity of a forest can be expressed by the Shannon Index of information content or uncertainty, H' (Pielou, 1969). The raw data for such an estimate are: S, the total number of tree spe- cies; Nit the number of trees for each (ith) species; and Nt, the total number of trees in the sample of all tree species (Nt = Ef= l Nf) where Ef=1 = the sum values of Nt from 1 to the total, S. The relative abundance (/?,) of the rth species is calculated as Pf = Nt/Nt, and diversity H' = â Ef=i p/lnpf, where In = natural logarithm to base e = 2.718 The measure of diversity takes into account both the number of tree species and their relative abundances. H' measures the de- gree of uncertainty that an individual drawn at random from the population will belong to a particular species. H' increases with the number of species and, for a given number of species, will be greatest when all species have an equal number of individuals, i.e., when the distribution of trees among species is even. H' will be zero with only one species. H' can be applied equally well to estimating the diversity of primates or to estimating food items in the diet. RECORDING CLIMATIC DATA During a short survey the best that one can do is to record tem- perature, relative humidity, and frequency of rainfall. A maxi- mum-minimum thermometer and a sling psychrometer will suf- fice. Long-term studies require a rain gauge and daily recording of the precipitation. If one has records for an annual cycle of daily rainfall and maximum and minimum temperatures, it is possible
26 TECHNIQUES IN PRIMATE POPULATION ECOLOGY to plot these data on a single graph according to the method de- veloped by Walter and Leith (1967); see Figure 3-8. When an annual plot of precipitation and temperature is estab- lished, the drought periods are clearly delimited. When the pre- cipitation curve falls below the temperature curve, this method of plotting reflects a drought in which plant growth is retarded. Average months of continuous drought are important; the longer the annual drought, the lower the annual plant productivity. The diversity of sympatric primate species clearly declines as the mean annual drought period increases over a range of geographic areas (Eisenberg, 1979). COLLECTING AND MARKING SPECIMENS Part of a habitat description may involve the assembly of plant and animal specimens. To be useful such collections must be ade- quately labeled and documented. LABELING GUIDELINES When collecting specimens it is important to get into the habit of keeping good notes and cross-references between the notes and the specimens. For this purpose it is useful to have tags that can be tied to the specimens. If specimens are being collected only sporadically, it may be adequate to number the specimens by date, since your notebook will probably be arranged chronologi- cally. Specimen 7/II/79-2 would be the second specimen col- lected on the seventh of February 1979. Turning to the notebook for that date, one would find a description of the specimen and a note on where it was collected. When specimens are being collected regularly or intensively, it is highly desirable to maintain a field catalog. The specimens should be numbered consecutively, preceded by your initials (e.g., RWT 735 or JFE 562). Never duplicate numbers. Keep the same series year after year. In both botanical and zoological col- lections, it is common to refer to the collector's numbers under the presumption that each applies uniquely to one specimen. Fruits and leaves bearing the same number are presumed to come from the same plant. The same would be true for a skull and leg
Habitat Description and Specimen Collection 27 a ) Morton Plains 500 -i 250 - 50 - b) Botticaloa 500 -i ' ' Jan 1 Dec L 0 Month | Wet Q] Transitional 03 Dry c) Batticaloa 500 -i _. 250 - E 100 - Â§ 50- 0- Month Jan Year Jul 1967 i . . . . . i r,-r-" ,=n Jul Jan Jul 1968 1969 FIGURE 3-8 Climatic diagrams. This figure presents a rapid method from Walter and Leith (1967) for characterizing the seasonal variation in rainfall for two areas in Sri Lanka. In these diagrams, the temperature as a monthly mean is plotted in centigrade up to 50Â° on the left-hand ordinate. The scale is in 10Â° in- crements that correspond to increments of 20 mm of precipitation on the right- hand ordinate. Precipitation is plotted as the monthly total, and when the total for any month exceeds 100 mm the scale is altered to 200 mm in months. The abscissa is scaled in months. The diagrams illustrate the differences between the climates of a wet-zone cloud forest at Horton Plains, which averages 2,000 mm of rainfall annually (Rudran, 1973a), and a coastal dry-zone forest at Batticaloa, which averages 1,699 mm of rainfall annually (McKay, 1973). The influence of monsoons on the amount and patterning of rainfall between years is striking in dry-zone habitats. This variabil- ity is illustrated in b and c, which contrast the data from individual years with 30-yr averages recorded by the Meteorological Department of Sri Lanka.
28 TECHNIQUES IN PRIMATE POPULATION ECOLOGY bones, all bearing the same collector's number. Examples of field catalogs, journals, and specimen labels are illustrated in many texts and pamphlets on mammalogy (e.g., DeBlase and Martin, 1974; Hall, 1962; Hall and Kelson, 1959; Setzer, 1963). COLLECTING PLANT SPECIMENS There are two main reasons for collecting plants used by the ani- mals one studies. First, this enables one to identify the species of the plants. Second, it enables one to demonstrate that the identi- fications are correct. Thus, even if one "knows" what the plants are, it is desirable to have voucher specimens. Since most speci- mens will be examined by a botanist and deposited in a herbar- ium, it is important to collect and press specimens carefully. Botanists are far more helpful if one's specimens are well pre- pared. Herbaria appreciate being given specimens identified by their staffs, so duplicates should be collected if one wishes to re- tain an identified series. The herbaria of the world are listed by Holmgren and Keuken (1974). The basic material needed is a plant press and the means to dry specimens. A plant press can be made from strips of wood fas- tened together to make a lattice. Two of these with straps around them constitute the press. Two boards and two pieces of light rope could also be used, as could a board and a big rock, but such presses make it harder to dry the specimens. The plants are placed between pieces of absorbent paper, such as folded newspaper, so that each sample, consisting of material from no more than one plant, is within its own fold. These are placed in the press be- tween blotters, newspapers, or pieces of cardboard. Some sort of corrugated material, such as corrugated cardboard, is needed so that dry air can pass through the press. The corrugations should run the width of the press so that when the press is tightened and put on its edge over a source of low heat, the drier warm air will pass upward through the press. When the specimens are collected, they should be numbered and an entry should be made in the field catalog. Note the size of the plant; describe the colors of flowers and sap, texture of bark, and so on. If you have numbered and labeled the trees in your study site, be sure to note these numbers also.
Habitat Description and Specimen Collection 29 One should collect specimens with flowers and fruits whenever possible. The specimen should be large enough to show leafing and branching patterns, but remember that herbarium sheets are generally 11" X 16" and the pressed specimens must fit. Small plants may be collected wholeâdon't forget the roots. Large specimens may be folded, as long as important features are not obscured. Press the plants as soon as possible, while they are fresh and unwilted. Under some circumstances specimens can temporarily be kept in plastic bags, preferably one specimen per bag so that they do not become mixed. When pressing specimens, arrange them so as to show the major features (e.g., both sides of leaves). Make sure the catalog numbers are with the plants in the press. To prevent molding, dry the plants as rapidly as possible in the press, but do not scorch them. Change wet blotters or newspapers as necessary, but do not remove the plants from their newspaper folders. It is best not to remove the plants from the folds of news- paper in which they are pressed until they are mounted on her- barium paper. The plants may be stored in newspaper, or they may be sent to a herbarium in newspaper. Any arrangement simulating a warming oven may be used as a plant drier. Plants are often dried in a box. Make a series of small (0.5 cm in diameter) openings in the bottom and top of the box so that heat can rise. Place the box over a small light bulb (25 watts) or other heat source. Each specimen sent to a botanist or a herbarium should have the following data included: data collected, collector's full name and his catalog number for the specimen, locality from which the specimen was collected, habitat (e.g., forest, savanna, swamp), and descriptive characteristics of the plant. Fruits are commonly preserved dry. They may also be preserved in fluid: 70% alcohol or FAA (5% formalin, 5% acetic acid, in 70% alcohol). Large fruits may need to be lanced or sectioned to ensure rapid fixation. They can be stored in wide-mouthed mason jars. For shipping they can be wrapped in cloth dampened with the preserving fluid and sealed in plastic bags. Botanists' collection techniques are described in more detail and illustrated in several books and pamphlets (e.g., Fosberg and Sachet, 1965; Shetler, 1963; Smith, 1971).
30 TECHNIQUES IN PRIMATE POPULATION ECOLOGY SCAVENGING ANIMAL REMAINS During field work one occasionally finds dead primates or skele- tal material. These specimens constitute a "graveyard sample" and can be very valuable. They can provide information on the ages at which animals die, data on nutritional stress, frequencies of fractures, and even the causes of sickness and death. These materials should therefore be saved and cataloged. The date, lo- cation, and state of decomposition should be recorded when the carcass is first encountered. A smelly, maggot-ridden monkey cadaver is not an attractive acquisition. In some areas you can leave it until it has dried and then take possession; but in others it must be taken promptlyâ before it is removed by scavenging animals or birds. You can hang it from a tree to discourage vultures and small scavengers from dragging it away, but if it starts to fall apart, important parts may be lost. If wire screening is available, you can make a cage to put it in. Make sure that vultures cannot reach into the cage and pull parts of it out. If the cage excludes vertebrates but not invertebrates, the skeleton will soon be cleaned, but it may be necessary to soften the skin in water and cut it off the skeleton. Less desirably, the carcass can be buried for a few weeks, then ex- humed. In some localities a cadaver can be left in slowly moving water, where invertebrate scavengers will clean it efficiently. If the cadaver is fresh, or one's stomach is strong, one can "rough it out" by removing the skin, viscera, and major muscle masses. Frequently this job is not as bad as anticipated if the viscera are first removed and disposed of. The skull should be separated carefully from the atlas, the eyes removed from their sockets, and the brain removed through the foramen magnum. The last can be done with a long-handled scoop, or a stick, or by injecting a jet of water inside the skull, as with a syringe. The "roughed out" car- cass can then be dried, later prepared with dermestid beetles, or it can be boiled. The former is preferable. Since the skull is generally the most valuable part, it should always be saved. Be careful not to loose the teeth, which can be used for estimating the age of the animal. The weight of the eye lenses also is frequently used to estimate ages of dead mammals.
Habitat Description and Specimen Collection 31 In some areas and with some species of primates, there may be a risk of disease associated with handling dead animals. The risk is probably greatest among primates most closely related to man, and the risk probably decreases rapidly with the length of time that the animal has been dead. With freshly dead animals, one should take care not to be bitten by any of their ectoparasites. With all cadavers one should take reasonable precaution to avoid viral and bacterial contamination of oneself and one's colleagues. The preparation of mammal skeletons for study is described in more detail by Anon. (1967), Hall and Russell (1933), Hoff- meister and Lee (1963), and Russell (1947). PHENOLOGICAL PATTERNS Phenology is the study of periodicity in the production of plant parts by individuals at a defined site and time. Typical pheno- phases that are discriminated include the vegetative parts (shoots, flush or young leaves, and mature leaves) and the repro- ductive parts (buds, blossoms, and unripe and ripe fruit). Fruit frequently changes color as it ripens. The period of leaffall is also monitored. Plants differ in the seasonal periodicity and sequential pattern- ing of their phenological activity. Trees may be ranked from ev- ergreen to brevideciduous, semideciduous, or deciduous; the ranking depends on the type of leaf renewal and the extent and duration of leaffall. Evergreen species produce new leaves as they lose old ones. At the other extreme, deciduous species tend to be highly seasonal, and some renew their canopies only after a period of dormancy. These patterns are usually given operational definitions at each site. Plants may produce flowers and leaves si- multaneously, alternately, or with some overlap of these activities. Reproductive patterns are equally variable. Trees may flower continuously, seasonally at a regular period of the year, aperiodi- cally, or gregariously; in gregarious flowering, neighboring indi- viduals show the same rhythmicity. Trees may also remain inac- tive reproductively for extended periods (up to several years) until a critical stimulus is present or until a required dormancy is satis- fied. Several tree species have separate male and female individ-
32 TECHNIQUES IN PRIMATE POPULATION ECOLOGY uals. Care should be taken to select female individuals of dioe- cious species in order to develop an estimate of fruit availability. A tree species may maintain continuous activity of a particular phenophase through continuous production at certain sites, by asynchronous behavior between branches of an individual, or by asynchronous behavior between individuals in a population. As many as 27 types of reproductive patterns have been described for species of plants in a seasonal rain forest in Panama (Croat, 1975). The patterns of dispersing or concentrating resources over time and space have been considered adaptive strategies through which plant species attract pollinators and dispersal agents and augment chemical defenses for avoiding seed predators. The focus of attention on the interaction between plant and animal species has led to a new examination of phenological patterns that are only partly explained as responses to limiting climatic factorsâfor example, rainy seasons and dry seasons, and changes in temperature and day length. The strategies of differ- ent plants directly affect the daily ranging patterns of primates; these patterns include not only their foraging times but also spac- ing within groups during foraging and the distances they move between resources. For example, it may be advantageous for a tree to attract arboreal herbivores if they are also seed dispersers, but advantageous to discourage them otherwise. A number of phenological patterns have been described in recent studies con- ducted both in the New World tropics (Croat, 1975; Daubenmire, 1972; Frankie et al., 1974a,b; Monasterio and Sarmiento, 1976) and in the Old World tropics (Hladik, 1978; Koelmeyer, 1959, 1960). Phenological data are useful because they can be compared with observations on feeding in order to develop a picture of the availability and utilization of different food items. Therefore, plant species selected for monitoring should be important food items of the primate under study or common plants in the area. Many plants are eaten seasonally at restricted periods and may represent important food items at those times. Mapping of plant species and monitoring phenology with the grid established for vegetation analysis and within the home range of the main pri- mate group increase the likelihood of observing the actual utiliza-
Habitat Description and Specimen Collection 33 tion of plants in the phenological sample. It is often necessary to use a sequential numbering system to identify the plants selected for the phenological sample prior to obtaining taxonomic identifi- cations of voucher specimens (see Chapter 6). The more frequently selected plants are trees and shrubs; those less frequently selected are vines, epiphytes, and herbs. Several individuals of each tree species are marked with num- bered tags or tape for recognition at each sampling period. Mature individuals that do not show obvious signs of disease are selected. A sample consisting of 5-10 individuals per species may be as large a sample as can be recorded on a monthly basis. (You might be working with, say, 30 species, and you would have a sample of 300 trees if you selected 10 individuals for each species.) More frequent monitoring is necessary for some species. Each phenophase is estimated as a percentage of the canopy. Percentages may be estimated broadly on a scale of 10 with each number representing 10% of the canopy. The data are recorded rapidly on prepared checksheets that provide columns for each of the phenophases (buds, blossoms, unripe and ripe fruits, young and mature leaves, leaffall) and a list of the identifications of the trees or other plants in the sample. The results are then tabulated or graphed and are contrasted with climatic variables that in- fluence them (e.g., rainfall). SATELLITE IMAGERY Satellite analysis of land resources has been an expanding area of study in forestry, agriculture, and geology since 1972, when the Earth Resources LANDSAT Satellites began transmitting data col- lected by multispectral optical sensors to ground receiving sta- tions worldwide. Photographic enlargements are made for study from the images, which were obtained at scales ranging from 1:3, 369,000 to 1:250,000 from the early LANDSAT satellite and are ob- tained at a scale of 1:125,000 from the current (1980) LANDSAT 3 satellite. The resolution at this scale means that 1 cm of the photograph represents 1.25 km on the ground and thus is much less than that available from recent aerial photographs or topo- graphic maps.
34 TECHNIQUES IN PRIMATE POPULATION ECOLOGY Different surfaces on earth reflect characteristic amounts of light that can be discriminated as intensity differences in images. These reflective differences can be used to discriminate and clar- ify forests, crops, water bodies, and geologic features. Seasonal changes in maturing vegetation of well-known crops and changes in species composition within large forest tracts can be detected by using these methods. These classifications are developed in conjunction with observations at selected sites that provide "ground truth" for extrapolations to larger areas. The standar- ized Forest Survey Information Data Sheet is illustrated in Ap- pendix C. It provides a means of describing habitats and has been used by the Royal Thai Forest Department for interpreting LAND- SAT data. Potential applications for satellite imagery increase as the tech- nology moves from an experimental stage to one where the infor- mation can be used in evaluating changes in land-use patterns and in managing resources (National Research Council, 1977). Studies of tropical forests using remote-sensing techniques and guidelines for gathering ground truth information have been de- scribed at recent international symposia (International Sympo- sium on Remote Sensing of the Environment, 1978, 1980). These studies include vegetation classifications and forest inventories in Brazil, Mexico, the Peruvian Amazon, Nigerian Forest Reserves, Thailand, the Philippines, and Indonesia. Initial applications of satellite imagery to primate studies may be in classifying forest types and in detecting and monitoring habitat loss for forest pri- mates through deforestation. NASA has recently published a volume on monitoring forest canopy in tropical countries using LANDSAT imagery. Data acquired by the LANDSAT satellite is transmitted to three receiving stations in the United States (located at NASA facilities in Greenbelt, Maryland; Goldstone, California; and Fairbanks, Alaska) to two stations in Canada and to one each in Brazil, Italy, Japan, and Sweden. Additional tracking and receiving stations are planned in Argentina, Australia, and China. The principal distribution facility in the United States for remotely sensed data is the EROS Data Center, Geological Survey, U.S. Department of the Interior, Washington, D.C. The Resource Planning Unit of
Habitat Description and Specimen Collection 35 the World Bank and the Remote Sensing Program of the U.S. Agency for International Development are important sources of information on remote sensing. Tropical countries that have LANDSAT programs include Bolivia, Brazil, India, Indonesia, Pakistan, Peru, the Philippines, Tanzania, and Thailand. In- quiries about the service offered and price lists for satellite images can be obtained from LANDSAT data distribution centers (see Ap- pendix A). Private firms and academic institutions in the United States have also begun to provide image processing and inter- pretive series (see Appendix B).