Quantitative evaluation of individual food intake by insectivorous vespertilionid bats (Chiroptera, Vespertilionidae)

Marharyta Moiseienko,Anton Vlaschenko

doi:10.1242/bio.058511

Abstract

ABSTRACTInsectivorous bats provide important ecosystem services, especially by suppressing and controlling the insects’ biomass. To empirically quantify the number of insects consumed by European vespertilionid bats per night, we estimated their ratio of dry mass of feces to mass of consumed insects. This study combines the results of feeding in captivity and the data obtained in field surveys; dry mass of feces was measured in both cases. In captivity, we analyzed the effect of species, age and sex of bats, species of insects consumed and the mass of food portion on the dry mass of feces. Using coefficients of the regression model, we estimated the number of insects consumed by free-ranging bats based on dry mass of their feces. According to our estimates, on average, one individual of one of the largest European bat species, Nyctalus noctula, consumes 2.2 g (ranging from 0.5 to 8.2 g) of insects per one feeding night, while the smallest European bats of genus Pipistrellus consume 0.4 g (ranging from 0.1 to 1.3 g), further confirming the importance of insectivorous bats for ecosystem services. This publication offers the novel method for the estimation of insects’ biomass consumed by bats.

Highlights

Insectivorous bats play a key role in suppressing insect populations, including crops’ and monoculture tree plantations’ pests
We aimed to evaluate the effect of different factors on the digestion level in captive bats and, based on these results, to estimate the amounts of insects consumed by bats in the wild
Rates calculated in in-captivity experiment Multiple regression analysis of linear model (LM) (1) for mass of feces (Table 1) showed that the mass of feces did not differ significantly between E. serotinus and P. kuhlii (P>0.1) as well as between E. serotinus and N. noctula bats (P>0.1)

Summary

Introduction

Insectivorous bats play a key role in suppressing insect populations, including crops’ and monoculture tree plantations’ pests. Published data suggest that insectivorous bats belong to the main controllers of arthropod pests (Boyles et al, 2011; Kunz et al, 2011; Russo et al, 2018) suppressing insects due to their nightly foraging activities. One of the main obstacles to such estimations is limited data on the actual number of insects each bat consumes (Boyles et al, 2013). Several publications provide some estimates of the number of insects consumed by bats, covering a broad geographical, ecological and species range (Simmons, 2005; Kunz et al, 2011; Kasso and Balakrishnan, 2013).

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Results