Groups Of Frugivores Research Articles

Geophagy in New Guinea birds

Geophagy, the ingestion of soil, has been reported for birds and other animals from many regions, but its functions remain debated. We report geophagy for the first time for New Guinea birds: four or five parrot species, two or three pigeon species, one hornbill species, one crow species and possibly one cassowary species. These species ate soil at an area of bare ground created by a landslide on a steep mountain slope. Parrots visited the site in the early morning, pigeons in the late afternoon, flying in from considerable distances. All 11 of these species are frugivores. In the vicinity, we recorded 133 other bird species (including 37 other frugivore species) that were not observed to visit the site. Within each taxonomic group of frugivores, those practising geophagy tended to be the largest species of their guild. To test hypotheses regarding the functions of geophagy, we carried out chemical and physical analyses of soil samples from the site. The ingested soil was much too fine‐grained to be useful as grit; it contained only modest levels of all 14 minerals analysed; it lacked buffering capacity; and there was no evidence that it protected against diarrhoea. Instead, the soil's high measured cation‐exchange capacity, high content of cation‐binding minerals and binding of large quantities of tannic acid and quinine suggest a different hypothesis: that geophagy in this case served to bind poisonous and/or bitter‐tasting secondary compounds in ingested fruits and seeds. Geophagy thus represents one weapon in the escalating biological warfare between plants and animal consumers‐an evolutionary arms race at which parrots excel. We discuss five unsolved problems posed by geophagy.

Dietary Overlap in Frugivorous and Insectivorous Bats from Edaphic Cerrado Habitats of Brazil

Previous studies on size patterns within frugivorous and insectivorous bat guilds from north-eastern Brazil suggest significant ecological separation of species. Nonetheless, recent simulation studies indicate that stochastic processes alone, rather than competition or coevolution, account for the morphological structure of these communities. To evaluate the dietary consequences of observed morphological structure, monthly samples of bats were collected (September 1976–May 1978) within edaphic Cerrado habitats on the Chapada do Araripe in northeastern Brazil. For each of the 11 most common species, stomach contents were identified, and the diets characterized for wet and dry seasons. Nonparametric statistical analyses of dietary constituents revealed two non-overlapping groups of frugivores based upon a posteriori contrasts: those that specialize on one food source, Vismia sp. ( Carollia perspicillata, Artibeus planirostris, A. lituratus ), and those that are more generalistic in their feeding habits ( Glossophaga soricina, Sturnira lilium, Vampyrops lineatus ). Statistical analyses of insectivorous species produced a homogeneous group ( Anoura geoffroyi, Phyllostomus discolor, P. hastatus, Molossus molossus ) based on classification of diet into hard-bodied versus soft-bodied insects. Like the ecomorphological assessments of community structure, our results failed to detect pervasive dietary differences among species that are related to size considerations.

Relative brain size, stratification, and social structure in anthropoids

The relationships between relative brain size and both stratification and social structure were examined in a total of 82 species of anthropoids. The species were divided into a total of 42 congeneric groups which consisted of congeneric species with similar ecologies and social structures. The relative brain size (RBS) was calculated for each congeneric group in each superfamily, based on an allometric equation describing the relationship between brain weight and body weight for each superfamily. Among congeneric groups with a common category of diet, RBS was significantly greater for terrestrial groups than for arboreal groups, and for polygynous (i.e. multi-female) groups than for monogynous (single-female) groups. Furthermore, RBS was significantly and positively correlated with the size of the home range per individual for the Cercopithecoidea, and with troop size for frugivorous groups of the Ceboidea. The results obtained suggest that factors associated with terrestriality and polygyny have been involved in the increases in relative brain size of anthropoids.

Fig Fruit Consumption and Seed Dispersal by Artibeus jamaicensis in the Llanos of Venezuela

Fig Fruit Consumption and Seed Dispersal by Artibeus jamaicensis in the Llanos of Venezuela