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Several species of birds deliberately drop hard food items, such as walnuts and molluscs, from high places to break the shell and eat the content. Although the carrion crow Corvus corone preys on the introduced apple snail Pomacea canaliculata by directly breaking the shells with their beaks in paddy fields in Japan, snails living in ponds are too large and hard for crows to directly break the shells. We found that carrion crows dropped apple snails in and around dried ponds in winter in Marugame, Kagawa, Japan, and conducted detailed observations on their predation behaviour. The crows dropped the snails onto various substrates in and around Hachijo Pond, and the release point was higher when the substrate was wet mud than when it was concrete, rock, or grass. As carrion crows rarely prey on other freshwater snails in Japan, this foraging behaviour has likely developed since the introduction of apple snails in the 1980s. The intense predation by the crows likely reduced the snail density in this reservoir pond. [ABSTRACT FROM AUTHOR]

Apple snails Pomacea canaliculata and Pomacea maculata are herbivorous freshwater gastropods native to South America and are introduced species widespread in western and southern Japan. Although they affect rice culture and are invasive to native ecosystems, high‐resolution distribution data are not available for these species. I mapped the distribution of Pomacea species using the citizen science approach, by asking volunteers to report the geographical location along with the presence or absence of apple snail egg capsules or snail shells during 2017–2019. In total, 1,304 present and 508 absent records were collected, which revealed the distribution outlines of apple snails, especially in the Kansai area. Here, I provide a dataset of observation dates, location coordinates, volunteer names, and supplemental information. The complete data set for this abstract published in the Data Paper section of the journal is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2020-19.1/jalter-en. [ABSTRACT FROM AUTHOR]