Detection of earthworm chaetae in mammal faeces: methodological implications

Abstract

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A refined method for estimating the number of earthworm chaetae in carnivore feces

“…The results of this study suggest that badgers may eat Lumbricidae earthworms with longer chaeta sizes in spring, supporting the prediction of Hijikata et al (2020). Battisti et al (2019) reported that the conversion of the total number of chaetae to earthworm biomass should be cautiously performed when earthworm species with different chaeta sizes and numbers are eaten by the studied animals. In this study, different earthworm families were eaten by different carnivore species.…”

“…Washing of fecal samples to collect undigested specimens with various sieves can affect the detection of earthworm chaetae (Battisti et al, 2019). Thus, method C detected earthworm chaetae more efficiently than the other two methods in this study.…”

“…However, various issues with dietary analysis using fecal samples have been discussed in several studies (Battisti et al, 2019;Reynolds & Aebischer, 1991;Zabala & Zuberogoitia, 2003). Reynolds and Aebischer (1991) reported that the "old" scats have lower overall densities than "fresh" scats.…”

“…Therefore, the wet weight of scats can vary depending on the age of scats at the point of sampling and may become a bias in estimating the number of chaetae of earthworms in a fecal sample, especially when only a subsample is analyzed and the total number of chaetae is estimated using the total weight of the fecal sample to save labor. Battisti et al (2019) recently reported that the detection of earthworm chaetae in fecal analysis can be adversely affected by examining the effect of the mesh size of the sieves used when washing the fecal samples. Consequently, to avoid these biases and accurately detect earthworm remains in carnivore feces, measurement of the wet weight of fecal samples should be standardized, and the number of earthworm chaetae in a fecal sample should be estimated before washing the samples.…”

Dietary Habits of Japanese Badgers (Meles anakuma) in Northern Japan: Relationship with Food Availability

“…It is difficult to detect earthworm remnants in feces because they are broken into small pieces during mastication (Battisti et al 2019; Tsukada et al 2021). Therefore, we employed a different method to evaluate earthworm feeding by the badgers, modified from Seki et al (2015): we kept water used for washing fecal samples for 15 min, and picked up its sediments (approximately 1 ml) using a dropper.…”