Inter‐ and intraspecific comparisons of retention time in insectivorous bat species (Vespertilionidae)

Abstract

Like other small terrestrial mammals, bats have a high mass‐specific energetic demand because of the fact that they have an unfavorable surface area to volume ratio. Furthermore, bats have a very energy‐expensive mode of locomotion: flight. This high energetic demand has to be covered by food intake. The retention time of the digestive tract is one factor affecting the energy intake of bat species. Factors like energy demand, gut volume and dietary specialization influence retention time in mammals. However, maximum retention time for only Myotis myotis and transit time only for M. lucifugus, Nyctophilius gloudi and Nyctalus noctula is known. This study investigated the maximum retention times and transit times of 10 Central European bat species. It was hypothesized that the level of specialization of the digestive tract, energy‐demanding processes and intestine length would affect the retention time of bats. Fluorescence‐marked mealworms Tenebrio molitor were used to measure the time between the first ingested mealworm and the first appearance of the marker or the last fluorescing feces, respectively. For the first time, the retention time of 10 insectivorous bat species was measured to determine interspecific differences. Additionally, we measured the retention time of post‐lactating female and spermatogenically active male Pipistrellus pipistrellus to determine intraspecific differences. The retention time of bats differed significantly between species and is probably influenced by the level of specialization of the digestive tract. High‐level specialization of the digestive tract resulted in short retention times. Furthermore, significant intraspecific differences between post‐lactating and spermatogenically active individuals of P. pipistrellus showed that the retention time within a single species might be influenced by energy‐demanding processes (e.g. reproduction).

Digestive Adaptations of Aerial Lifestyles

“…Additionally, anecdotal evidence suggests that bats also have generally shorter retention times that nonflyers (i.e., see data in Refs. 13,50,54,58,93,103), although passage rate may not differ significantly (50). In summary, both birds and bats have smaller small intestines with smaller nominal surface areas than nonflying mammals, and both groups have shorter retention of digesta than nonflyers.…”

Detection ofPseudogymnoascus destructanson Free-flying Male Bats Captured During Summer in the Southeastern USA

“…Accumulation of Pd in guano likely results from bats ingesting the fungus from body surfaces during grooming, and WNS-positive bats are known to groom more frequently than do uninfected bats (Brownlee-Bouboulis and Reeder 2013). Furthermore, gastrointestinal transit studies in various species of insectivorous bats demonstrate nearly complete passage of food items within 24 h (Lukens et al 1971;Buchler 1975;Stalinski 1994;Roswag et al 2012). Therefore, detection of Pd in fresh guano collected from bats captured at evening emergence suggested recent ingestion of the fungus.…”

Insectivorous Bats Digest Chitin in the Stomach Using Acidic Mammalian Chitinase

“…European bat species have a diet consisting predominantly of arthropods [5]. They have short retention times [6] but a high digestive efficiency [7]. This suggests that their gastrointestinal (GI) tract is highly adapted to their diet since it digests arthropods quickly and thoroughly.…”