16 



lower vegetation levels, approaching individual plants in a trap-lining way keeping a 

 certain sequence and sometimes covering considerable distances. On their way tlie bats 

 regularly visit night shelters for about half an hour. G. soricina approaches flowering 

 plants both individually and in groups, the size of the latter depending on tlie number of 

 open blossoms per night and tree. 



As reported by Barbour & Davis (1969), Leptonycteris nivalis leave their roost 

 comparatively late in the evening, but detailed information on their activity is still to 

 come. 



Clironological shifts in activity rhythms within the same habitat were reported by Koepcke 

 (1987) in Panguana (Peru) m three sympatric nectar feeding genera: Lonchophylla thomasi 

 always flew into the nets before 9 p.m., Choeroniscus intennediiis between 8 and 11 p.m. 

 and Anoiira caiidifer never before midnight. 



The Glossophaginae represent smaU to mid-sized PhyUostomatidae with a reduced 

 dentition, a distinctly elongated nose and a widely protrusible tongue - all adaptations to 

 a feeding specialization on nectar and soft fruit. In ecological respect they represent 

 nocturnal equivalents of himimingbirds, and their development may partially have been 

 influenced by similar paraUel evolutionary constrains. This is shown in many similarities 

 (weight liniit, ability of hovering, elongated tongue, prolongation of the rostral skull). 

 They usually feed during hovering, but sometmies tlie bats will go down onto the 

 blossom, thereby impairing furtlier development of the fruit with the claws. 



Body size and weight 



In contrast to frugivorous Phyllostomids which often grow quite large, the highly 

 specialized nectar feeding bats range at the lower level of body size and weight (cf. tab.2). 

 This is partly explained by ecological aspects of the flowers, as size and stnicmre of "bat 

 blossoms" must be sufficiently resistant to bear the weight of approaching and often even 

 landing bats. On the other hand, body size of these anmials will be essentially limited by 

 Table 2: Body length and weight of blossom-feeding Microchiroptera (adapted from Dobat & Felke rt 

 1985) 



Feeding biology / Feeding ecology 



Chiropteran adaptations to nectari- and pollenivory 



body length 

 (mm) 



weight (g) 



Vampymw spectrum 

 Phyllostomiis hastatus 

 Phyllostomus discolor 



125-135 

 100-130 



145-190 



52,2-101,1 



22,2-40,0 



Leptonycteris nivalis 

 Glossophaga soricina 

 Anoiira geoffroyi 



Choeronycteris harrisoni 

 Choeronycteris mexicana 



75- 91 

 80-89 

 60-86 



76- 78 

 48-84 

 60 



11,3-17,7 

 7,6 



7,1-8,1 



ca. 25 

 10-20 

 18-30 

 5,4-12,7 



Choeroniscus godmani 

 Lichonxcteris obscu ra 



53-58 

 46-55 



