The pygmy marmoset population of a 3-km2 sample area of Amazonian lowland forest was censused and monitored intensively between September 1976 and January 1978. Floodplain forest constituted the habitat of Cebuella and supported a population density of 51.5 independently locomoting individuals (ILI) per square kilometer. The highest population concentration occurred along the edges of the river, where the density reached 274 ILI per km2. Adults comprised about one half of the total population. About 83% of the population lived in stable troops; the remaining 17% was made up by incipiently associated pairs and solitary individuals. Stable troops were made up of 1 breeding female, her mate, and her maturing offspring of up to four successive litters. Moreover, some troops contained 1–2 additional adult members. Troop size ranged from 2 to 9 ILI, with a modal size of 6 ILI. The births showed two annual peaks and the interbirth intervals ranged between 5 and 7 months. Infant survival was about 67%. Exudates (sap and gums) of trees and vines, insects and arachnids constituted the principal food resources of the population. The troops occupied exclusive home ranges of 0.2–0.4 ha. Several troops changed home range sites temporarily or permanently in the course of the study.
Saguinus fuscicollis illigeri was studied intermittently over a period of 5 years. Quantitative data on the diet, habitat use, ranging, and daily activities of one focal troop were gathered between November 1979 and January 1982. Modal troop size was 6 independently moving animals (observed range: 2–10). Troop size fluctuated over time, largely due to subadult/adult emigrations and immigrations. Population density was 15 animals/km2. Births occurred year-round, but a clear-cut peak season extended from December to March. The study troop occupied a defended home range of 15.7–16.5 ha. Treefall habitat was preferred over all other habitat types, and only 27% of the daytime was spent in non-edge tall-forest habitat. The troop spent 82% of the daytime in the lower forest strata (50% in the shrub stratum), below 11 m, and only 2 % in the highest stratum, above 20 m. Daily path length averaged 1,405 m. Daily ranging pattern showed seasonal changes related to seasonal fluctuation of fruit availability. Daily activities consisted of insect foraging (45 %), resting and grooming (32%), feeding on plant resources (14%), travel (6%), watching (2%), and others (1 %). Fruits, plant exudate, nectar, arthropods, frogs and lizards comprised the principal food resources. Fruit was the most important plant food, except during the peak dry season when 58% of plant-feeding time was spent consuming exudate. Nectar was an important resource in the early dry season. Bachelor groups of Saimiri boliviensis associated frequently with the study troop, and Saimiri was the most important resource competitor. The tamarins showed strong and consistent avoidance behavior towards Cebus apella.
RESUMENDesde 1979 se viene realizando estudios y propagación de Podocnemis expansa, P. unifilis y P. sextuberculata en la RNPS.Como consecuencia de la fuerte explotación clandestina, se estima que la población actual de hembras adultas de P. expansa en la RNPS no sería mayor de 500 -600. P. unifilis, en cambio, es común, excepto en las zonas periféricas. P. sextuberculata es escaso en el interio pero común en los ríos periféricos de la RNPS. Desovan durante el estiaje (julio-octubre) y las crías emergen de los nidos en octubre -diciembre. Desovan principalmente en playas de arena de los ríos, pero P. unifilis también lo hace comunmente en otros tipos de orillas. Desovan mayormente de noche, pero P. expansa y P. unifilis lo hacen también de día. P. expansa pone 61 -172 huevos, P. unifilis 6 -52 y P. sextuberculata 7 -22. El período de incubación y permanencia de las crías eclosionadas en el nido dura 69 -87 días, con diferencias interespecíficas. La saca clandestina de huevos y desovadoras es la mayor amenaza para la supervivencia de estos quelonios en la RNPS. El programa de manejo de quelonios acuaticos de la RNPS ha incubado y liberado cerca de 179,000 crías, incluyendo 57,000 de P. expansa, y ha iniciado un programa de manejo participativo de este recurso con algunas comunidades locales.
RESUMENDesde 1979 hasta 1992 se investigó la ecología del coto, Alouatta seniculus en el río Pacaya medio, con énfasis en los aspectos de densidad poblacional, organización social, reproducción, uso de hábitat y alimentación. La población de cotos se compone de grupos heterosexuales, grupos formados únicamente de machos y animales solitarios. Los grupos heterosexuales se componen de 2 a 11 (excepcionalmente hasta 13) integrantes (promedio = 5.54). Cada grupo tiene generalmente 1-2 (promedio = 1.3) machos adultos y 1-3 (promedio = 1.8) hembras adultas. Los adultos constituían aproximadamente el 60% de la población total. La densidad poblacional fue 36 animales/km2. En la Reserva Nacional Pacaya Sumiría el coto es el mamífero arbóreo de mayor biomasa (162 kg/km2 en el área del estudio). Los nacimientos ocurren durante todo el año, pero con mayor frecuencia en octubre-abril y son muy escasos en julio-setiembre. Los intervalos observados entre nacimientos sucesivos fluctúan de 15 a 28 meses. Las crías son cargadas hasta 5-6 meses de edad y únicamente por las hembras. Los cotos ocupan principalmente los estratos superiores del bosque, pero en marzo mayo frecuentan también el estrato inferior, El coto fue el único primate que se ha observado cruzar voluntariamente a nado el río, por lo que éstos no constituyen una barrera mayor de dispersión para esta especie. Las áreas domiciliarias de grupos contiguos se sobreponen parcialmente; para 2 grupos éstas tenían una extensión aproximada de 9 ha y 6 ha, respectivamente. El coto se alimenta principalmente de hojas e yemas (53% de la dieta anual), frutos (40%) y flores (6%), pero también de pecíolos, ramitas tiernas y brotes terminales de lianas. La composición proporcional de la dieta fluctúa estacionalmente, siendo los frutos el recurso más importante (64.7%) en la estación medio de lluvia (enero-marzo) y las hojas y yemas en las otras estaciones.* Instituto de Investigaciones de la Amazonía Peruana (IIAP). Av. Abelardo Quiñónez. Km. 2.5.Apartado 784. Iquitos -Perú.
Proyecto Primates and Ministerw a!e Agriculturo, Regi6n Agraria XXII, Iquitos, PeruThe sociosexual behavior of a free-ranging Cebuella pygmaea troop containing two adult males was studied throughout a postpartum periestrous period of its reproductive female. A clear-cut male-initiated six-day behavioral estrous period occurred from the 13th through 18th day postpartum, with a two-day peak of mating activity on the 15th and 16th days. Both adult males attempted to mate with the female, but the dominant male maintained exclusive mating access to her by guarding behavior and aggression toward the subordinate male. Estrus-related changes in the daily activity pattern included constant following of the female by the male, increased huddling and grooming between the consorts, a decrease in infant carrying, and suppression of insect foraging in the consorting male. Behaviors seen only during the periestrous period included genital presenting by the female, intensive licking and sniffing of her genitalia by the males, female-guarding by the dominant male, anogenital scent-marking on the male's body by the female, tongue protrusion and "tongue vibrating" by the male, and copulations, play chasing, and ffconsort walking" by the couple. Within the Callitrichidae, genital presenting and tongue vibrating in sexual context have been observed only in Cebuella.
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