In May 2021, we opportunistically observed one Eurasian jay (Garrulus glandarius) attacking an adult incubating Japanese tit (Parus minor) and depredating nine tit eggs at a nest box where a woodpecker had greatly enlarged the entrance. After the predation event, the Japanese tits abandoned the nest. We recommend that when using artificial nest boxes to protect hole-nesting birds, the appropriate entrance size should be proportional to the body size of the target species. This observation gives us a better understanding of the potential predators of secondary hole-nesting birds.
Keywords: hole size; nest predation; secondary hole‐nesting birds; video monitoring.
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