Date of Award
Doctor of Philosophy
Understanding spatial and temporal diversity and distribution patterns of species along with the drivers of these patterns has long been a theme of community ecology. Primates, a very species-rich taxonomic group, able to occupy various habitat types, are known for their broad behavioral repertoire and flexibility. This, in turn, allows them to adapt quickly to different ecological conditions. Therefore, they represent an ideal group for examining aspects of community ecology such as species diversity and co-occurrence, distribution patterns, and the ecological determinants of such factors. This dissertation investigates the ways in which members of a multispecies primate community inhabiting a mosaic landscape comprised of flooded and non-flooded forests in northeastern Peru (western Amazonia) distributes themselves across time and space. The main objectives of this study are threefold: 1) to categorize, confirm, and differentiate previously identified habitat types across a mosaic landscape; 2) to examine the diversity and distribution patterns (spatial and temporal) of a large multispecies primate community, and 3) to combine the habitat data with the primate data in order to determine which habitats are occupied by which species and to suggest ways in which the primates share and utilize the landscape throughout an annual cycle. However, special attention is paid to one particular species, the red uakari (Cacajao calvus ucayalii), because of its unusually large home and day ranges and its fluid social system known to change in size and composition daily and even hourly. One of the least studied primates to date, red uakaris, are investigated in order to determine whether or not their behavior varies across habitat types, seasons, and when other primates are present as they navigate a mosaic landscape. By identifying the ways in which uakaris modify their behaviors as they traverse multiple habitats throughout the year, determining both habitat-typical behaviors and seasonal behaviors exhibited by uakaris becomes possible. Moreover, shedding light on the community structure and habitat requirements of one of the least known primates has conservation implications. Research was conducted at the Tahuayo River Amazon Research Center (TRARC), located in northeastern Peru. Systematic data collection on primates and the environment occurred between September 2012 and February 2014, except April 2013. Sampling methods for primates consisted of two parts—a combination of line transect and reconnaissance (recce) surveys in order to determine encounter rates for each species across habitat types and 10-minute interval scan sampling during uakari follows in order to determine the effect that environmental and social factors have on their behavior as they traverse multiple habitats. Environmental sampling occurred in thirty plots established throughout the various habitat types. All trees within the test plots with a diameter breast height (DBH) > 10 cm were marked and the following parameters were recorded: DBH, height, and taxonomic classification. Additionally, plots were monitored monthly to record flooding data in order to determine variation in flooding patterns across habitat types. Plots allowed for the determination of which floristic variables and flood patterns are suitable to differentiate the habitat types described at the TRARC. Results indicate flood duration, average tree height, and (Importance Value Indices [IVIs] at the family, genus, and species levels) are suitable measures for defining and differentiating the five previously identified habitat types at the TRARC. Analysis of the entire primate community showed that the occurrence of species and patterns of distribution across a mosaic landscape vary throughout the year. Distribution patterns are more dependent on forest structure (habitat type) than on rainfall seasonality. While a few primates showed preferences for particular habitats (e.g., Lagothrix) or for certain seasons (e.g. Saimiri), the majority of primates demonstrated more generalized modes of ranging and foraging, with relatively equal encounter rates in all habitats across both wet and dry seasons. Results of the uakari data revealed that habitat and season had an effect on their behavior. There were meaningful differences in the behavioral categories of vocalizing, resting, moving, feeding, infant clinging, and being in polyspecific associations (PSAs) between flooded and non-flooded habitat types. Seasonal differences were seen for vocalizing, traveling, resting, and time spent in PSAs. Although results revealed that red uakaris spent the majority of the time alone (71.86%), when they were in PSAs with one other primate species, squirrel monkeys (Saimiri sciureus) were the most common monkeys. When uakaris were in PSAs with two other species, squirrel monkeys were always present, but woolly monkeys (Lagothrix lagotricha poeppigii) were the second most frequent species. In general, uakaris demonstrated behavioral differences across habitats and seasons. However, some behavioral consistencies across seasons were evident (e.g., moving, feeding, infant clinging), suggesting ecological flexibility in the species. Results of this dissertation provide a basis for understanding ecological parameters best suited for characterizing and differentiating habitat types in upper Amazonia and describe the diversity and distribution patterns of a multispecies community of primates occurring across a mosaic landscape, reinforcing the view that New World primates are largely ecological generalists within forest environments. Understanding the spatio-temporal relationships between species and their environments can aid in predictions of species occurrence/abundance and contribute to better management strategies and conservation prioritization.
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