Determining the availability of earthworms for visually hunting predators

Onrust, J., Hobma, S. & Piersma, T., 11-Nov-2019, In : Wildlife Society Bulletin. 43, 4, p. 745-751 7 p.

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  • Determining the Availability of Earthwormsfor Visually Hunting Predators

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Studies of interactions among earthworms as prey for visually foraging predators required a field method that measures earthworm availability (i.e., the density of surfacing earthworms). We present such a method by counting surfacing earthworms at night by an observer lying prone on a cart propelled by an observer across measured distances at constant low speed. The method was applied in dairy farmland grasslands in The Netherlands during October and November 2011. We quantified the numbers of surfacing earthworms as well as those measured during standard hand-sorting sampling (i.e., total abundance based on soil counts), distinguishing clay or peat soils and grasslands with either monocultures or species-rich vegetation. Managed grasslands with different soil types showed opposing correlations between surface availability and total abundance of earthworms. This emphasizes the importance of direct measurements of earthworm availability if the goal of the study is to explain the behavior of either visual earthworm predators or earthworms themselves. (c) 2019 The Wildlife Society.

Original languageEnglish
Pages (from-to)745-751
Number of pages7
JournalWildlife Society Bulletin
Issue number4
Publication statusPublished - 11-Nov-2019


  • earthworm abundance, earthworm availability, foraging ecology, Lumbricidae, methodology, VANELLUS-VANELLUS, FEEDING ECOLOGY, ATHENE-NOCTUA, MELES-MELES, FOOD, MANAGEMENT, LUMBRICIDS, BEHAVIOR, POPULATIONS, LANDSCAPE

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