15 



There is also one Venezuelan report on eight specimens hanging beneath a log which had 

 fallen across a river (Sanborn 1954). 



Choewnycteris: C. mexicana is known from various habitats, from arid brier to tropical 

 secondary forest and mixed oak wood (Arroyo-Cabrales et al. 1987). As day shelters they 

 prefer caves and deserted adits, usually clinging themselves at dmi recesses next to the 

 entrance. So, they accept even very small caves. There is some controversy about whether 

 they congregate with other species: whereas Goodwin (1946) regarded C. mexicana as a 

 mostly solitary species merely moving about, there have been later reports on various 

 Vespertilionidae and Tadarida, also Glossophaga, sharing their roost sites with these bats. 

 They occupy both caves and artificial shelters. Davis & Russell (1954) found a group of 

 C. mexicana hanging beneath a tree. The individuals cling seperately 2 - 5 cm apart from 

 each other, usually holding grip with only one foot and thus capable of observing intruders 

 by rotating their body up to 360 degrees. C. mexicana is an extremely alert, easily startled 

 species, which will rather leave the roost immediately than move to darker sites (Barbour 

 & Davis 1969). 



Activity Patterns 



Brown (1968) pointed out how activity patterns depend on diet: correspondingly, 

 insectivorous species are most active in the early evening, whereas frugivorous and 

 piscivorous bats show almost equal activity patterns all over the night. In the sanguivorous 

 Desmodontidae, the activity pattern is mainly determined by darkness, as these bats are 

 most active at complete darkness. Nectar feeding bats leave their roosts soon after sunset 

 heading for their host plants according to certain patterns, so their activity pattern 

 sometimes may be bimodal. They are, however, certainly active during the first half of the 

 night. 



Detailed information is available for only few species. 



There are some observations on the food intake of Lonchophylla thomasi from east Peru 

 by Koepcke (1987) showing that these bats leave their roosts at complete darkness not 

 before 18.25 or 18.35. One specimen covered with pollen was caught around 9 p.m.; at 

 least one activity phase occurs during the first night hours. 



As reported by Swanepoel & Genoways (1983), BrachyphyUa cavernariim leave their day 

 shelter some time after nightfall, at least one hour after sunset and some 20 minutes later 

 than Artibeiis. First, all individuals of a colony fly out synchronously, finishing their 

 activity almost as simultaneously within the very last minutes before sunrise. 

 Activity patterns of Glossophaga soricina were studied by Erkert & Kracht (1978), 

 revealing that this species is influenced by a quite inflexible circadian system which 

 synchronizes with hght and is induced by sunset, with a free periodic length of just 23.4 

 to 25 hours merely adapting to external stimuli. In eastern Peru, Koepcke (1987) captured 

 foraging G. soricina shortly before midnight, and they were observed at banana blossoms 

 in the early morning as well. In a similar way Sazima & Sazima (1978) reported an 

 accumulation of foraging bats between 1.20 and 4.00 a.m., with activity maxima in the 

 evening and during the last night hours (La Val 1970; Bonaccorso 1979). 

 According to Fleming et al. (1972), Sazima & Sazima (1978), Bonaccorso (1979) and 

 Koepcke (1987), spatial distribution of food supply determines the flight routes in G. 

 soricina. Depending on the pollen suppliers available, the species heads for higher or 



