Nest defense is an effective strategy of hosts against parasites. Typically, hosts will aggressively attack brood parasites that approach or visit their nests, which can prevent the parasites from laying eggs or may even lead to the death of the parasites. Few previous studies have specifically reported such fatal cases involving brood parasites and have attributed the cause of death to either drowning or hypothermia after falling into the water following an attack from hosts. In this study, we recorded the process of multiple host individuals of the Oriental reed warbler (Acrocephalus orientalis) mobbing and attacking a female common cuckoo (Cuculus canorus) in the field. We discovered that the immediate cause of the cuckoo's death was the fatal physical damage resulting from the aggressive defense from the hosts, suggesting that frantic pecking and scratching by the hosts is the most proximate cause of mortality among egg‐laying female cuckoos. This finding enhances our essential understanding of the effectiveness of host attacks.

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Birds select suitable nest sites for breeding to ensure their own and offspring's survival; however, they inevitably suffer some potential predation risk. We studied the breeding ecology of Daurian redstarts ( Phoenicurus auroreus ) by providing nest boxes for their breeding from March to August of 2022. We recorded the predation of both Daurian redstarts eggs or nestlings by Oriental magpie‐robins ( Copsychus saularis ) and tree sparrow ( Passer montanus ). Oriental magpie‐robin were recorded attacking a feeding female adult and depredating nestlings. After the nestling predation event, the Daurian redstarts abandoned the nest. This video evidence provide a better understanding of the potential predators of cavity‐nesting birds.