Estimation of food intake and ingested energy in Daubenton’s bats (Myotis daubentonii) during pregnancy and spermatogenesis

Abstract

We studied food intake of and estimated ingested energy in female and male Myotis daubentonii during the periods of pregnancy (period 1, 8 May-4 June) and of intense spermatogenetic activity (period 2, 24 July-22 August) over 8 years (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003) in central Germany. We used radiotelemetry to determine the time spent foraging and marked animals with chemiluminescent light-sticks to determine prey attack rates. Body length, body mass, moisture content, and caloric content of chironomids, the main prey of Daubenton's bats, were measured to estimate the nightly food intake and, in consequence, energy intake. Pregnant females spent significantly more time foraging than males during period 1 and females during the post-lactation period. In contrast, male foraged longer during the period of highest spermatogenetic activity than during late spring and also significantly longer than post-lactating females. Based on a mean number of 8.3 prey attacks per minute, the time spent foraging, and a capture success rate of either 50 or 92%, calculated intake values with a feeding rate of 7.6 insects per minute (=92% capture success) were more consistent with literature data for other insectivorous bats than that of values calculated on the basis of a capture success rate of 50%. In the high capture-success model, calculated insect intake of female bats was 8.0 g during pregnancy and 4.9 g per day during post-lactation, providing 5.0 and 3.0 kJ of ingested energy per gram body mass per day. Calculated intake of male bats was 3.6 g insects per day during late spring and 8.0 g during period of intensive spermatogenesis, providing 2.6 and 5.7 kJ of ingested energy per gram body mass.

A mosaic of opportunities? Spatio-temporal patterns of bat diversity and activity in a strongly humanized Mediterranean wetland

“…However, since pregnancy and lactation occur during summer, bat activity was expected to be higher in this season due to the increased energy demands of these life-cycle stages (Kunz 1973;Encarnação and Dietz 2006). However, the lower activity we registered during summer might be due to lower bat detectability resulting from significant noise disturbance produced by katydids.…”

Discovery of Parameters for Animation of Midge Swarms

“…Chironomids are small (less than 2 cm long [3]) and relatively ubiquitous. Male chironomids form mating swarms.…”

“…• body length: [9,3] -minimum: 0.2 to 1.0 cm -maximum = minimum + x, where x is 0.1 to 0.3 cm • preferred speed in still air: 16.8 cm/s [10] -minimum: 10.0 to 14.0 cm/s -maximum: 17.5 to 21.0 cm/s • maximum acceleration: 100 to 500 cm/s 2 [6] • zone of repulsion: 1.2 cm [9] • maximum turning rate: 2π rad/s…”

“…4 [3] ( 4) where y is the mass in grams and x is the body length in centimeters. When x is small, y can become negative, so we set a minimum mass of 0.0005 g. The minimum and maximum body length, minimum and maximum speed, and maximum acceleration characteristics are used as parameters by the genetic algorithm.…”

Reproductive and age classes do not change spatial dynamics of foraging long-fingered bats (Myotis capaccinii)

“…Some stages in the bat's life cycle (typically lactation or spermatogenesis) require a higher energetic intake (Kurta et al 1989;Kurta et al 1990;Speakman and Thomas 2003;Encarnação and Dietz 2006). Accordingly, lactating females and spermatogenic males have usually been found to spend more time foraging compared with other individuals (Rydell 1993;Shiel et al 1999;Barclay et al 2000;Encarnação and Dietz 2006; but see Dietz and Kalko 2007).…”