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Nutrient Requirements of Nonhuman Primates: Second Revised Edition, 2003
Semnopithecus (Presbytis)
S. entellus
Hanuman langur
In remote, wild areas: young leaves 26% (0-69%), mature leaves 26% (0-79%) fruit 34% (0-72%), of which about 3% is seeds (0-45%), flowers and buds 9% (0-43%), stem 1.6%; other 3%; more insects than other colobines; near farms: 90% of diet is cultivated crops; Himalayan subspp eat pinecones, bark, twigs during snowy winter months
Troops near temples eat offerings, raid crops; diurnal, terrestrial, and arboreal, 1 male or multimale/ multifemale, groups 11-262 individuals
Young leaves and shoots 32% (9-52%), mature leaves and petioles 26% (1-61%), fruit 32% (1-55%), of which 7% is seeds (0-40%); flowers and buds 10% (0-43%), insects <1%, other 0.5%; more mature leaves than Presbytis and much of fruit eaten unripe; raids crop; T. pileatus - animal prey 1.6%, gum and termite soil
Diurnal, arboreal (some also terrestrial), 1 (some 2) male and multifemale, groups 2-40 individuals
bBody weights in ranges whenever possible; single numbers are not averages but indicate that only one individual of the species has been weighed in the wild.
cNo data available from the wild but assumed to be similar to congenerics.
ited use for quantifying a diet, because the time required for food acquisition varies.
Time Sampling Methods Less complete but more manageable methods for recording feeding behavior, these are probably the most commonly used today. These methods also require independent start-and-stop rules, and dawn and dusk are often used.
One-Zero Sampling. A behavior is scored only once per observation period, regardless of the number of times it occurs. This method is adequate for preliminary reconnaissance. It is not recommended for detailed feeding-ecology studies, because it generally yields poor ‘‘time-spent’’ estimates.
Instantaneous Sampling. The observer records a focal-animal’s behavior at predetermined times. This method works well with ongoing behavior that can be timed with a stopwatch, such as feeding behavior. For example, during a feeding bout, what the animal is eating every 30 or 60 seconds is recorded. Another approach is to observe the focal animal every 15 min and record all behaviors for 5 min. A limitation of this approach is that rare events often are not recorded. However, when continuous observations prove impossible, this generally is considered the next-best method.
Scan Sampling. Instantaneous observations are made of several animals simultaneously. This is useful for studying less-detailed behavior.
Alternative Feeding-Ecology Methods
In some circumstances, particularly if terrestrial primates are being studied in dense rainforest, visual observations of feeding behavior are impractical. It can be impossible to see the animals well enough to determine what they are eating or how much time they spend eating it, and alternative methods might be needed. Some researchers studying nocturnal animals use both visual observations and alternative methods (Nash 1983). Alternative methods for studying feeding ecology are outlined below.
ANALYSIS OF STOMACH CONTENTS
Measurement of stomach contents, now rare, can be used to estimate the mass of different food categories consumed (for example, fruit, leaves, or insects); with care and skill, one can identify the species eaten (Booth, 1956; Fooden, 1964; Charles-Dominique, 1974; Gautier-Hion et al., 1980). However, because the animal must be killed, only a single measure per animal is obtained. An additional
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