When faced with a predator, parent birds have to choose between current and future breeding. Previous studies have shown that the body condition and personality of parents influence the trade-offs. However, whether body condition and personality influence an individual's nest defense behavior has rarely been investigated. Here, we studied whether body condition and personality affect the nest defense behavior of incubating Japanese tits (Parus minor). Some females exhibited intense nest defense behavior when human-simulated intruders approached. Notably, individuals exhibiting high nest defense behavior had significantly shorter tail lengths compared to individuals who did not. In addition, bold individuals would exhibit higher nest defense behavior than those showing low defense responses. Furthermore, bold individuals consistently demonstrated stronger nest defense behavior compared to shy individuals, aligning with their proactive personality traits. This pattern highlights the potential role of individual behavioral differences in shaping anti-predator strategies.

Keywords: Body condition; Hissing call; Nest defense; Nest predation; Personality.

© 2025. The Author(s).

当面临捕食者时，亲鸟必须在当前和未来的繁殖之间做出选择。之前的研究表明，父母的身体状况和个人性格会影响这种权衡。然而，身体状况和个人性格是否影响个体的筑巢防御行为很少被研究过。在这里，我们研究了身体状况和个人性格如何影响日本䴓（Parus minor）孵化期间的筑巢防御行为。一些雌鸟在人类模拟入侵者接近时表现出强烈的筑巢防御行为。值得注意的是，表现高筑巢防御行为的个体尾长明显短于没有表现出这种行为的个体。此外，大胆的个体比低防御反应的个体展示更高的筑巢防御行为。另外，大胆的个体一贯表现出比害羞个体更强的筑巢防御行为，这与其主动的性格特征相一致。这一模式突显了个体行为差异在塑造反捕食策略中的潜在作用。

关键词：身体状况；嘶叫；筑巢防御；巢穴捕食；性格。

© 2025. 作者保留所有权利。