This study is an experimental evaluation of the predictions for three reasons: (1) it is much hypothesis that differences in nest positions less disturbed in the presence of man than within and outside Ad&e Penguin colonies are most colonial sea birds, (2) it is subject influence behavior, egg loss rates, and nest to predation upon eggs and chicks, and (3) characteristics. "Colony" and "rookery" are theft of nest material from neighbors is conused in this report as defined for Ad&lies by spicuous and frequent. Also, the breeding Penney (X365:85): "A colony is a geograph-behavior and ecology of the Ad&lie is the ically continuous group of breeding birds best known of the Antarctic penguins. whose territorial boundaries are contiguous," and a rookery is a "geographical area. .. that METHODS contains one or more colonies." The actions of predators and conspecifics The study was conducted at Cape Hallet (72" 18' 50" S, 170" 13' 00" E), Victoria Land, Antarctica, during within a dense nesting colony of Ad&es or the 1967-1968 austral summer. The Cape Hallet other sea birds are highly predictable. Nests Ad&e Penguin rookery occupies about 40 ha of a are regularly spaced, just far enough apart to low lying spit ("Seabee Spit"), approximately 1000 m allow owners of adjacent territories to touch long and 200-650 m wide, projecting into the Moubray Bay inlet of the Ross Sea (fig. 1). Maximum elevabills when reaching toward one another from tion of the spit is about 5' mT This rookery was detheir nests. This "social pattern" (Hutchinson scribed and mapped by Reid (1964) who recognized 1953) minimizes disturbances within the col-more than 600 colonies at Hallet, ranging in size from ony. A predator hunting eggs or chicks may less than 10 to more than 1200 nests. Reid (1964:15) have difficulty directing its attention to any censused the breeding population at Cape Hallet and single nest because it is always within peck-found it to be 62,900 pairs in the 1959-1960 breeding season and 61,955 pairs in the 1960-1961 season. A ing distance of other nests. For the same census made during the present study identified about reason a conspecific has difficulty approach-43,000 breeding pairs (Brett Tumbull and Thomas ing a nest to steal nest material (a habit found Choate, pers. comm.). among many colonial sea birds, e.g., see Fisher The experiments described in this report were conand Lockley 1954) or to otherwise disturb its ducted 5-11 December 1967 during the late incubation phase of the Ad&lie breeding cycle. Data collecoccupant. Colony perimeters furnish less pretion was confined to this brief period to allow a dictable living spaces, and single nest sites temporal cross-sectional comparison among birds nestentirely separated from colonies are even more ing in different locations. First hatching occurred on unpredictable. Intruders can approach pe-9 December and the peak of hatching was 16-17 rimeter nests from outside the colony without December. The Ad&lie' s incubation period averages 35-37 days (Penney 1968:93), so the birds e...

Behavior of Kloss’ gibbons was studied from July 1 to October 7, 1972 in Siberut Island, off the coast of western Sumatra, Indonesia. Reproductive groups are monogamous families with a mean family size of 3.4 individuals (n = 11 families). Such families occupy territories averaging 6.7 ha. Adults defend their territories only against members of the same sex. This intrasexual defense of territory maintains the monogamous mating system. Other social units were unmated resident females, unmated resident males, floating males, and a courting pair. Males establish territories before mating, perhaps with help from their parents. Males guard their families against predators. Females lead progression through the territory. Subadults remain peripheral to their families but other family members tend to remain within 10 m of one another.

Kloss's gibbons (Hylobates Klossii) and Mentawai langurs (Presbytis potenziani) on Siberut Island, Indonesia, both sleep in emergent trees 34-55m tall, situated on crests and upper slopes of hills. They differ in that 91% of gibbon sleeping trees examined were free of lianas, whereas 89% of langur sleeping trees were draped with thick, woody lianas hanging from the branches to the ground. Because indigenous hunters climb lianas to shoot primates in treetops, gibbons are less susceptible than langurs to nocturnal human predation. Hence, the gibbons' preference for-and apparent control of-the limited supply of vineless trees gives them an advantage over langurs.

No abstract

This study evaluates the social spacing mechanism of song as it occurs in Kloss' gibbons. The study population included individuals in 13 family groups whose composition and territories were known (Tenaza 1975) plus a number of others. Sonagrams illustrate individual and sexual differences in singing. Sex differences in chorusing, countersinging and other behavior related to song are described. Variations in singing or chorusing or both are related to season, time of day, sex, age, spatial factors and social factors. The adaptive functions of singing, countersinging and chorusing are discussed. It is concluded that: (1) Song is mainly for interterritorial communication between members of the same sex, (2) ♂ ‐song probably also functions in mate attraction and (3) chorusing is primarily an adaptation reducing predation risk to singing gibbons.