A case report of an Eurasian Jay (Garrulus glandarius) attacking an incubating adult and depredating the eggs of the Japanese Tit (Parus minor)

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 nestbox 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.

2021年5月，我们机会性观察到一只松鸦（Eurasian Jay，Garrulus glandarius）袭击了正在孵卵的成年日本山雀（Japanese Tit，Parus minor），并在一个入口被啄木鸟大幅扩大的人工巢箱内掠食了9枚山雀卵。此次捕食事件发生后，该巢箱内的日本山雀弃巢离去。我们建议，在利用人工巢箱保护洞栖鸟类时，巢箱的适宜入口尺寸应与目标物种的体型相匹配。本次观察有助于我们更深入地了解次级洞巢鸟类的潜在捕食者类群。