The aim of our study was to assess the seasonal and overnight changes in the flight activity and habitat use of four bat species under the conditions of a sub-mountain town by a detector monitoring. The urban habitats visited from May untill October 1998 – 2000 were divided into three categories: gardens (illuminated or non-illuminated gardens and larger groups of trees), urban habitat (old and new buildings in suburbs and downtown), and water (streams and ponds). Only for Myotis daubentonii was a statistically significant increase in flight activity recorded between the lactation and post-lactation periods. The highest activity of M. daubentonii was recorded in the vicinity of water bodies. The activities of Pipistrellus pipistrellus and Nyctalus noctula were similar in relation to the habitats. Only in Eptesicus serotinus was the activity recorded per habitat type not significantly different. The changes of activity of P. pipistrellus had a bimodal character with the first peak in the 5th and the 6th ten-minutes and the second in the 12th ten-minutes. In N. noctula, activity was characterized by commuting over the urban habitats during the first 0.5 h. Relatively high activity was recorded in E. serotinus during the first 0.5 h in gardens.
Host-parasite relationships between the Daubenton's bat, Myotis daubentonii Kuhl, 1817 (Chiroptera: Vespertilionidae), and its haematophagous ectoparasite, the mite Spinturnix andegavinus Kolenati, 1857 (Acari: Spinturnicidae), were subjected to analyses based on data gathered during a six-year study (1999-2004) within a single study area in South Bohemia, Czech Republic. Seven hundred and fifty-one Daubenton's bats were examined by screening wing membranes with an intensive light source, resulting in 4,690 recorded mites. Sex, age, weight and reproductive state were evaluated for each bat. A body condition index was calculated as a ratio of weight to forearm length. The seasonal course of mite infestation displayed distinct dynamics with the peak during the lactation and post-lactation periods coinciding with occurrence of the most numerous colonies of Daubenton's bats in the study area. Infestation rates differed between the two sexes, being higher in adult females than adult males. Juvenile bats of both sexes (with no differences between males and females) were the most infested group of all. Pregnant females had a significantly higher parasite load than non-pregnant ones, while no differences in infestation rates were found between lactating and non-lactating females. The analyses of the relationship between parasite load and body condition of bats revealed no common trends for all sex- and age-related groups. Two possible explanations are suggested and discussed: (1) There is no true relationship between the two tested variables and, thus, the significant results were attained due to a random statistical effect. (2) Different underlying causal mechanisms may exist that influence parasite load and, especially, body condition, with respect to the particular sex and age category of bats. The seasonal roosting dynamics of the Daubenton's bat are suggested to be the result not only of changing energetic demands of resident population members, but also of coevolutionary strategies within host-parasite relationships.
In Norway, very few bats are found in caves and mines in winter, thus other habitats must be primary hibernation sites in this region. To explore roost site selection in late autumn and early winter at 62° N in western Norway, 18 bats of three genera of the Vespertilionidae family that are known to use underground hibernation sites were tagged with radio transmitters. The bats were tracked mostly during daytime between late September and up to
early January. Mainly three habitats were used by bats in late autumn in this
study; buildings, crevices in rock walls and rock scree. Roosts were distributed from sea level to the low alpine zone. Rock scree was confirmed as a hibernation site for bats.
We studied nocturnal activity in adult male Myotis daubentonii from mid-May to early September of the years 1998–2003 in a male-dominated population in central Germany. Departure from roost after sunset, nocturnal activity time, time spent foraging, and return to roost before sunrise were recorded in radio-tracked animals during four observation periods (1: 14 May – 6 June, 2: 16 June – 10 July, 3: 22 July – 14 August, 4: 23 August – 2 September). Only three males (two in period 1, one in period 4) stayed in the day roost all night. The other tracked animals left their day-roost for the first time between 25 and 220 minutes after sunset, and their last arrival at the day-roost occurred between 2 and 545 minutes before sunrise. Bats spent most of their nocturnal activity time foraging (overall mean: 79.7 % of nocturnal activity time). Duration of nocturnal activity and nightly foraging time varied considerably over the four observation periods and were most extended in mid-summer (period 3). This is a time of high spermatogenetic activity and steep increase in body mass (built-up of fat reserves), which leads to a particularly high food demand of male Daubenton’s bats during this period of the year. Our results of an increased foraging activity during mid-summer provide evidence in support of the view that food demand of male Daubenton’s bats is indeed highest during this time of the year.
Metabolic rate and body temperature (Tb) reduction during torpor can provide significant energy savings for bats during inclement weather and food scarcity. However, torpor use may slow down biochemical processes including fetal and juvenile development and sperm production. Sex-differences in the timing of reproductive activity of bats in the temperate climate zone should result in differences of the thermoregulation behaviour by males and females during summer. To test this hypothesis, we studied thermoregulation of freeranging, tree-dwelling gleaning bats (Myotis bechsteinii) and trawling bats (M. daubentonii) during different reproductive periods. Gleaners and trawlers are able to forage on prey which is sitting on vegetation and the ground (gleaning) or which is slowly moving over water bodies (trawling). This prey is characterized by lower ambient temperature (Ta) dependent abundance than flying prey. We used temperature-sensitive radio transmitters to measure skin temperature (Tsk). Temperature telemetry over 144 census days revealed a significant effect of reproductive period and sex on Tsk. Pre-spermatogenic males exhibited a significantly greater Tsk reduction than females in early pregnancy. Males at the beginning of sperm production and in main spermatogenesis exhibited much more frequent and deeper temperature reductions than females in late pregnancy and in lactation. Lactating females maintained the highest Tsk of all bats. Post-lactating females reduced Tsk to the same extent or even more than males in advanced spermatogenesis. Our findings indicate that the thermoregulation of gleaning and trawling temperate bats is likely to be much less influenced by environmental conditions than that of aerial hawking bat species. We suggest that both sexes of Bechstein’s bats and Daubenton’s bats primarily adapt their thermoregulation in response to current reproductive activity.