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In males of the grasshopper Chorthippus biguttulus the relationship between song and mating success was investigated in three isolated field populations of individually marked animals within their natural habitat. In a population with muted males (forewings removed), females mated on average 1.7 days later than in a population with intact males. But approximately 14 days after the imaginal moult, roughly corresponding with the time of the first oviposition, 100% of females in both populations had mated. In a further test population, females with a choice between singing and mute males mated almost exclusively (16 from 17 observed copulations) with the intact, singing males. The chance encounter frequency of a male and female was equally high for all populations (on average one encounter every 1.2 h). Different encounter probabilities cannot therefore have caused either mating delay in the population with muted males or preferential selection of intact partners.

In the Neotropics ongoing deforestation is producing open and heavily fragmented landscapes dominated by agriculture, mostly plantations and cattle pastures. After some time agriculture often becomes uneconomical and land is abandoned. Subsequent habitat regeneration may be slow because seed inputs are restricted by a lack of incentives--such as suitable roost sites--for seed dispersers to enter deforested areas. Increasing environmental awareness has fostered growing efforts to promote reforestation. Practical and cost-efficient methods for kick-starting forest regeneration are, however, lacking. We investigated whether artificial bat roosts for frugivorous bat species can attract these key seed dispersers to deforested areas, thereby increasing seed rain. We installed artificial bat roosts in a forest-pasture mosaic in the Costa Rican Atlantic lowlands and monitored bat colonization and seed dispersal. Colonization occurred within a few weeks of installation, and 10 species of bats occupied the artificial roosts. Five species of frugivorous or nectarivorous bats colonized artificial roosts permanently in both primary habitat and in deforested areas, in numbers similar to those found in natural roosts. Seed input around artificial roosts increased significantly. Sixty-nine different seed types, mostly of early-successional plant species, were transported by bats to artificial roosts in disturbed habitats. The installation of artificial bat roosts thus successfully attracted frugivorous bats and increased seed inputs into degraded sites. This method is likely to speed up early-vegetation succession, which in turn will attract additional seed dispersers, such as birds, and provide a microhabitat for seeds of mid- and late-successional plants. As well as supporting natural forest regeneration and bat conservation, this cost-efficient method can also increase environmental awareness among landowners.

We analysed the polygynous mating system of the bat Saccopteryx bilineata using behaviour observations and genetic data on 11 microsatellite DNA loci. Basic social units in S. bilineata are harem groups that consist of single males and up to eight females. Colonies comprise several harem groups, and the composition of colonies and harems is often stable over several reproductive seasons. The combination of parentage exclusion and likelihood-based parentage assignment in this study produced detailed parentage information for a large colony of S. bilineata. Reproduction occurred mostly within the colony (17% extra-colony paternity), but social associations in harems within the colony did not represent reproductive units (70% extra-harem paternity). The latter finding was consistent over three reproductive seasons. Spatial association of the roosting sites of males and females could not explain parentage patterns in the colony. Even though intra-harem paternity was less frequent than expected, it contributed significantly to reproduction of harem males. On average, the number of offspring sired by a male with females in his harem territory increased significantly with harem size, which corresponds to the higher energetic investment that is related to the maintenance of large harems. However, extra-harem paternity was not correlated with a male's harem size or intra-harem reproductive success. This suggests that individual preferences of females rather than male traits associated with the ability to defend large harems are most likely to cause the detected differences between social association and genetic mating system.

Field studies of elusive mammals such as Agouti paca are difficult, and results are often biased and incomplete because the animals are nocturnal and avoid traps. By studying an A. paca population in a Pacific lowland forest of Costa Rica, we developed indirect observational methods to estimate population density and food resource utilization. To estimate population density, we divided the number of A. paca burrows found in a 12-ha census area by the average number of burrows utilized per individual from radiotelemetry data. We compared this estimate to independent population estimates obtained using two transect methods. Agouti paca density was estimated at 93 individuals/km2 based on burrow number, and between 67 to 70 individuals/km2 using transect methods. This discrepancy corroborates previous studies suggesting that transect methods underestimate population density. To identify food resources consumed by the species, we collected fruits and seeds with unambiguous A. paca teeth marks. The only animal in Central America with an incisor width similar to A. paca. is Dasyprocta variegata; in a comparison of both species, however, we found that A. paca had a significantly larger incisor width and that teeth marks of 4 mm or wider unambiguously indicated handling by this species. By applying this technique, food resources utilized by A. paca can be identified more easily than by direct observation. At our study site, we identified 33 plant species consumed by A. paca; 61 percent are new records for this animal. Our results suggest that A. paca plays a major, although not fully understood, ecological role in seed predation and dispersal. RESUUMEN Estudios de campo sobre mamiferos elusivos como las Agouti para son intensivos tanto en tiempo como en labor, y resultan frequentemente parcialisados y incompletos debido a que estos animales son nocturnos y le temen a las trampas. Durante un estudio de la poblaci6n de A. paca en un bosque lluvioso de Cosca Rica, desarrollamos metodos de observacion indirectos para estimar la densidad y uso de recursos de la poblacion. Para estimar la densidad de la poblacion, dividimos el nlimero de madrigueras en el area de doce hectareas por el numero promedio de madrigueras utilizados por un individuo de los resultados de radiotelemetria. Comparamos esto estimado con otros obtenidos independientemente por metodos de transecto. Basado en el numero de madrigueras, se estimo la densidad de A. paca en 93 animales/km2, mientras que los estimados basados en observaciones de transectos dio entre 67 a 70 animaled km2. Tal diferencia podria confirmar estudios previos indicando que los metodos de transecto subestiman la densidad de poblaciones. Con el fin de identificar 10s recursos alimenticios consumidos por esta especie, recolectamos frutos y semillas marcas dentales de pacas. El unico animal en America Central con un ancho de diente incisivo similar al de la A. paca es Dasyprocta uariegata. En una comparacion de las dos especies encontramos que las A. puca tenian incisivos significativamente mas anchos, y que marcas dentales de 4 mm o mas indican sin ambiguedad manipulacion por esta especie. Aplicando esta tecnica, se puede identificar los recursos alimenticios utilizados por A. paca mas facilmente que mediante observaciones directas. En nuestro sitio de estudio identificamos 33 especies de plantas consumidas por pacas: 61 porciento son registros nuevos para este animal. Nuestros resultados indican que las A. paca representan una parte muy importante, pero todavia no muy bien entendida, en la depredacion y dispersion de semillas.