In many cooperatively breeding taxa, nonbreeding subordinates, or helpers, use extra-territorial forays to discover dispersal opportunities. Such forays are considered energetically costly and foraying birds face aggression from conspecific members of the territories they visit. In contrast, breeders in cooperatively breeding taxa are expected to foray seldomly. We used novel tracking technologies to follow 62 acorn woodpeckers (Melanerpes formicivorus), a cooperatively breeding bird, to study extra-territorial foray behavior. Both helpers and breeders engaged in extra-territorial forays routinely and often several times per day. Helpers forayed earlier in the day and invested more time when foraying to high-quality territories. Unexpectedly, breeders forayed as often and as far as helpers. Breeders from high-quality territories forayed closer to their home territories than breeders from low-quality territories, reflecting a potential tradeoff between foraying and territory defense. Such a routine pattern of extra-territorial forays in both helpers and breeders suggests that the motives behind forays differ by sex and social status and involve more than simply searching for dispersal opportunities.

中文翻译：

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流浪啄木鸟：社会鸟类的突袭行为

在许多合作繁殖的分类群中，非繁殖的下属或帮助者使用域外突袭来发现传播机会。这样的突袭被认为是精力充沛的代价，并且突袭的鸟类面临着来自它们所访问领土的同种成员的侵略。相比之下，合作育种类群的育种者预计很少涉足。我们使用新颖的追踪技术追踪了 62 只橡子啄木鸟 (Melanerpes formicivorus)，一种合作繁殖的鸟类，以研究域外攻击行为。帮手和饲养员都定期进行域外突袭，通常每天数次。帮手在当天早些时候进军，并在进军高质量领土时投入了更多时间。出乎意料的是，饲养员经常出手，也有帮手。来自优质领地的育种者比来自低质量领地的育种者更靠近他们的家乡，这反映了进攻和领土防御之间的潜在权衡。这种在帮助者和饲养者中进行域外袭击的常规模式表明，袭击背后的动机因性别和社会地位而异，并且不仅仅是寻找分散机会。