Raumnutzung und Fouragierverhalten des afrikanischen Langzungenflughundes Megaloglossus woermanni (Chiroptera: Pteropodidae) im Lama-Wald, Benin, Westafrika

In a radio-tracking study, I investigated space use and foraging behaviour of the nectarivorous African long-tongued bat, Megaloglossus woermanni (Chiroptera: Pteropodidae), in the Lama protected forest, southern Benin. Until now, the biology of this single obligate nectarivorous bat in Africa was almost unknown. During the study period from 23rd July to 11th October, I monitored the movement and activity patterns of two male and two female individuals that were fitted with position-sensitive transmitters. The study site contains a central patch of primary forest ("Noyau Central"), but greater parts of this area are characterized by a mosaic of orchards, agroforestry plantations, and degraded forest.The foraging strategy of M. woermanni was characterized by comparatively small home ranges and high site-fidelity during the study period. This behaviour was a consequence of the spatio-temporal availability of food resources, most probably combined with a solitary and flexible selection of day-roosts. Mean home range size, calculated as the minimum convex polygon, was larger in females (142.9 ha) than in males (101.4 ha). This difference is likely to be caused by lower contact times with males than with females. None of the bats’ day-roosts were found, but they were presumably located within bushes or trees of the Noyau Central, which forms the core area of the study site.During the study period, long-tongued bats visited flowers of cultivated bananas along the periphery of Lama Forest. No other flowering food plant was recorded. Three (2 MM, 1 F) out of four radio-tracked individuals showed a highly predictable and consistent foraging behaviour. These animals exploited the same banana patches throughout the observation period. A fourth individual (F) shifted its foraging area through adjacent patches between nights. All individuals were recaptured several times. This resident behaviour is likely to be caused by the high predictability of food resources since bananas showed long flowering periods and were regularly visited by the monitored individuals. The resource density of banana inflorescences in the study area was sufficient to meet the energy demands of the local population of M. woermanni. Nitrogen supply for the bats may have been limited during the study period as cultivated bananas do not produce pollen and samples collected from the fur and faeces contained only negligible amounts of other pollen.Within home ranges, I further investigated areas used for foraging as well as core areas of resource use. The mean foraging area of females, defined as the 95 % density kernel and pooled over the whole study period, was 74.2 ha and distinctly larger than in males (12.3 ha). However, the difference of core areas (calculated as the 50 % density kernel) between the sexes was less marked (FF: 6.8 ha, MM: 2.8 ha). Presumably, foraging and core areas of male bats would have been larger with higher contact time. Core areas constituted only a small part of home ranges (2.6 - 4.9 %). This reflects the patchy as well as clumped spatial distribution of banana patches within the study site. Large segments of home ranges were not used for foraging, but only for commuting flights between discrete resource patches.Flight activity of radio-tracked long-tongued bats varied considerably between individuals and nights. Pooled data revealed a bimodal activity pattern. On average, flight activity reached a maximum (45±7.1 % of contact time) between 19:30 and 20:00 hrs, with little flight activity during subsequent hours. A second but lower activity peak (29±19.6 % of contact time) was found between 5:30 and 6:00 hrs. Between 19:30 and 0:00 hrs and 4:30 and 6:00 hrs, high contact times with both males and females allowed me to compare activity patterns among sexes. During these periods, males spent significantly more time flying than females. In general, high activity levels at the beginning of the night might have been caused on the one hand by inspection flights aimed at the particular food resource situation of a given night and on the other hand to balance energetic deficits accumulated during daytime and commuting flights. The second activity peak can be interpreted as foraging activity to accumulate energy for the following day.Comparison with published studies showed that home range size, space use and activity patterns of M. woermanni are very similar to that of other nectarivorous bats of similar size and diet, i.e. the Australasian species Macroglossus minimus and Syconycteris australis. Previously, these species were thought to be closely related based on morphological similarities. New studies showed, however, that these species belong to different groups, indicating that similar diet and morphology is the result of convergent evolution rather than close phylogenetic relationships. Thus, nectarivory in pteropodids has evolved several times independently. My results on the ecology and behaviour of M. woermanni imply not only the convergent evolution of morphology and diet, but also of similar foraging strategies in these species. When comparing home range studies, it is important to consider the influence of different habitat structures. Habitat disturbances may lead to enlarged home ranges and altered resource availability. Consequences of such changes are largely unknown and need further investigation due to the crucial role of the interdependent relationships between plants and bats as pollinators in tropical ecosystems.