Comparative Feeding Ecology of Sympatric Microcebus berthae and M. murinus

Abstract

Most Malagasy primate communities harbor a diverse assemblage of omnivorous species. The mechanisms allowing the coexistence of closely related species are poorly understood, partly because only preliminary data on the feeding ecology of most species are available. We provide an exemplary feeding ecology data set to illuminate coexistence mechanisms between sympatric gray and Madame Berthe's mouse lemurs (Microcebus murinus, M. berthae). We studied their feeding ecology in Kirindy Forest/CFPF, a highly seasonal dry deciduous forest in western Madagascar. Between August 2002 and December 2007, we regularly (re-)captured, marked, and radiotracked females of both species. A combination of direct behavioral observations and fecal analyses revealed that both Microcebus species used fruit, arthropods, gum, insect secretions, and small vertebrates as food sources. However, Microcebus berthae and M. murinus differed in both composition and seasonal variation of their diets. Whereas the diet of Microcebus murinus varied seasonally and was generally more diverse, M. berthae relied mainly on insect secretions supplemented by animal matter. The differences were also reflected in a very narrow feeding niche of Microcebus berthae and a comparatively broad feeding niche of M. murinus. Resource use patterns of Madame Berthe's and more so of opportunistic gray mouse lemurs broadly followed resource availability within the strongly seasonal dry forest. Feeding niche overlap between the 2 sympatric species was high, indicating that food resource usage patterns did not reflect niche partitioning, but can instead be explained by constraints due to food availability.

Senescence or selective disappearance? Age trajectories of body mass in wild and captive populations of a small-bodied primate

“…Animals were captured with Sherman live traps (for details on capture and handling protocols, see [34,41]) 6 -10 times per year with a minimum trapping effort of monthly captures at the end of the rainy season (March -May) and at the end of the dry season (September -November). Only data from the months March -November were used in the analyses to reduce the influence of female pregnancy.…”

“…In mammals, including M. murinus [31], body growth typically ceases around the age of sexual maturity [32] (six to eight months in M. murinus [31,33]). Thereafter, BM fluctuates in response to imbalances in energy acquisition and expenditure, cyclic seasonal changes [21,34,35] or senescent muscle loss [36]. BM broadly reflects resources available for allocation to physiological processes, making it a meaningful indicator of FS.…”

“…However, in presence of conditiondependent mortality, these declines should be relatively minor in the wild compared with captivity. In the wild, the coping of aged individuals may be especially compromised in the ecologically more demanding dry season when food and water availability decline considerably [34], which might lead to more severe BM senescence (i.e. age-related declines in BM) in this season.…”

Females go where the food is: does the socio-ecological model explain variation in social organisation of solitary foragers?

“…Each trail intersection was marked for orientation, and their coordinates were used to create a map. In order to analyse seasonal patterns, we defined three time periods according to differences in rainfall and food availability: (S1) the transition between wet and dry season (Mar-May), (S2) the dry season (Jun-Sep) and (S3) the transition between dry and wet season (Oct-Dec; for details, see Dammhahn and Kappeler 2008b). …”

“…Specifically, we hypothesised that (1) M. berthae experience high levels of scramble competition and little potential for female-female association because they use small and quickly depleting resources (Dammhahn Wimmer et al 2002;Radespiel et al 2003;Fredsted et al 2005 d Sleeping associations (Radespiel et al 2001;Wimmer et al 2002) and communal breeding units (Eberle and Kappeler 2006) e In captivity : Perret 1992 and Kappeler 2008b). In contrast, because M. murinus use a wider variety of food sources, also including larger and higher quality resources (Dammhahn and Kappeler 2008b), we hypothesised that (2) they will experience high levels of contest competition as well as an increased potential for female-female association. We therefore made the following specific predictions based on the socio-ecological model as summarised in Koenig (2002): (1) Home range size and distance to nearest-neighbour females are positively related to local population size, i.e.…”