Foraging distance is a key determinant of colony survival and pollination potential in bumblebees Bombus spp. However this aspect of bumblebee ecology is poorly understood because of the difficulty in locating colonies of these central place foragers. Here, we used a combination of molecular microsatellite analyses, remote sensing and spatial analyses using kernel density estimates to estimate nest location and foraging distances for a large number of wild colonies of two species, and related these to the distribution of foraging habitats across an experimentally manipulated landscape. Mean foraging distances were 755 m for Bombus lapidarius and 775 m for B. pascuorum (using our most conservative estimation method). Colony-specific foraging distances of both species varied with landscape structure, decreasing as the proportion of foraging habitats increased. This is the first time that foraging distance in wild bumblebees has been shown to vary with resource availability. Our method offers a means of estimating foraging distances in social insects, and informs the scale of management required to conserve bumblebee populations and enhance their pollination services across different landscapes.

We assessed levels of genetic diversity and investigated patterns of population structure in three remnant populations of the endangered giant otter, Pteronura brasiliensis, using microsatellite loci. All populations displayed moderate to low levels of heterozygosity and allelic richness (H O 0.56-0.57, A R 4.00-5.15) and effective population sizes were low (N E 10.8-54) although only the Iténez population exhibited the signature of a genetic bottleneck. Population structure analyses revealed a pattern in which the populations of the Upper Amazon, Orinoco and Essequibo drainages comprised partially differentiated segments of a northern South American metapopulation, whereas the population of the Iténez appeared isolated. The observed patterns are congruent with previous mitochondrial DNA analysis which suggested the Iténez and northern South American groups constitute two evolutionary significant units. The results presented here should be considered in planning future policies aiming to manage the recovery of the giant otter across its range.

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Abstract:We report the results of a short expedition to the remote headwaters of the River Rewa, a tributary of the River Essequibo in the Rupununi, Southern Guyana. We used a combination of camera trapping, mist netting and spot count surveys to document the mammalian and avian diversity found in the region. We recorded a total of 33 mammal species including all 8 of Guyana's monkey species as well as threatened species such as lowland tapir (Tapirus terrestris), giant otter (Pteronura brasiliensis) and bush dog (Speothos venaticus). We Resumo: Reportamos os resultados de uma curta expedição às remotas cabeceiras do Rio Rewa, tributário do Rio Essequibo no interior da Guiana. Utilizamos uma combinação de armadilhas fotográficas, redes de neblina e avistamento para documentar a diversidade de mamíferos e aves encontrados na região. Nós registramos um total de 33 espécies de mamíferos, incluindo todas as oito espécies de primatas que ocorrem na Guyana, além de espécies ameaçadas como anta (Tapirus terrestris), ariranha (Pteronura brasiliensis) e cachorro-do-mato (Speothos venaticus). Nós registramos uma população mínima de 35 ariranhas em cinco grupos no 95 km do rio. Registramos também um total de 187 espécies de aves que pertencem a 47 diferentes famílias. Incluindo os dados gerados pelo Smithsonian Institution em 2006, a lista de espécies para a cabeceira do Rio Rewa aumenta para 252, com 48 famílias, incluindo 10 espécies endêmicas do escudo das Guianas e duas espécies consideradas raras: a harpia (Harpia harpyja) e o gavião-real-falso (Morphnus guianensis). Palavras-chave: Escuda da Guiana, conservação da biodiversidade, endêmicas e ameaçadas de aves, espécies ameaçadas de mamíferos, Rio do Rewa, Rupununi.