18 



tail {Phyllonyctens, MonophyUus) or an extensive tail membrane with the tail remaining 

 very short or lacking at all {Stenodenninae, Choeroniscus). Generally, the fmgivores tend 

 to develop a reduced iiropatagium, as they need to climb about on their host plants, 

 especially when the bats even have their roosts among the branchwork or the foliage. 

 Most nectar feeding bats possess reduced or entirely lacking tails {Leptonycteris, Anoiira). 

 Tlie degree of development does, however, not necessarily correspond to the degree of 

 specialization on nectar feeding (cf. figures of interfemoral membranes in 'Results: 

 morphology of the species examined'), but might also have been influenced by some 

 additional ecological demands. 



Pelage 



An overview on adaptations of harr structure to pollen intake was given by Howell & 

 Hodgkin (1976): even visible to the naked eye, living specimens have their nape hairs 

 standing up like the bristles of a bottle brush rather than recumbent as in other bats. 

 Further differences are revealed in their fine structure: whereas many Chiroptera usually 

 have a smooth hair shaft under the microscope, pollinating bats possess scales standing up 

 from the shaft, thus facihtating pollen fixing m the pelage. 



Fixing pollen is not only advantagous for the host plants to be pollinated - as nectar is 

 predominantly an energy supplier, the intake of pollen serves as an essential and 

 sometimes exclusive protein source. Accordmg to Howell (1974), analysis of stomach 

 contents in bats having been caught at their feeding plants always revealed nectar 

 exclusively in the stomach (and pollen only in the fur). Very probably the bats take up 

 pollen afterwards, grooming in their roosts. Howell (1974) described that the bats ingest 

 the pollen combed from the fur with the claws by constantly licking their feet. This 

 behaviour is also supported by faeces analysis (Harris 1959), showing that in no case there 

 was any anther material m the faeces of nectar feeders. Using the fur for pollen transport, 

 the animals keep full stomach capacity for their "fuel" (tlie nectar). Considering the 

 narrow hmits of their energy balance, this may be a pre-condition for efficient exploitation 

 of these resources (v. Helversen & Reyer 1984). 



Dobat & Peikert (1985:110) point to the fact that the chiropteran fur generally is well 

 suited for pollen transport, thus doubting the significance of Glossophagine fine hair 

 stnicture in allowing pollen transfer. Comparable conditions to those described by Howell 

 & Hodgkin (1976) were found independently in some non-pollenivorous bats. Tlius, the 

 fine strucure of the hair shaft enlarging the surface may be determined by different eco- 

 logical demands; tliis characteristic seems to occur widely among bats. Obviously, it 

 seems impossible to prove any anthophile specializations in polhnating bats compared 

 with insectivorous species, the scales on the hair shaft which are arranged like keratinized 

 cones - as foimd in the pelage of all nectar feeders - certainly represent ideal devices for 

 embedding and fixing pollen grams. 



Digestive tract 



Tongue 



The long, tapering, very protrusible and highly mobile tongue represents the characteristic 

 feature of speciaHzed nectar feeding bats. Its tip is covered with brush-like papillae 

 directed backward and thus enabling efficient nectar intake (Griffitlis 1978). The protrac- 

 tility of the tongue is incredible - Glossophaga can extend its tongue up to three times the 

 snout length. In the extremely long-nosed banana bat Choeronycteris harrisoni the 

 extended tongue is up to 76nmi long - corresponding body length of 80nmi (v. Helversen 

 1993). 



