Intraspecific phenotypic variability is key to respond to environmental changes and anomalies. However, documenting the emergence of behavioral diversification in natural populations has remained elusive due to the difficulty of observing such phenomenon at the right time and place. Here, we investigated how the emergence of a new trophic strategy in a population subjected to high fluctuations in the availability of its main trophic resource (migrating songbirds) affected the breeding performance, population structure, and population fitness of a specialized color polymorphic predator, the Eleonora’s falcon from the Canary Islands. Using long-term data (2007-2022), we found that the exploitation of an alternative prey (a local petrel species) was associated with the growth of a previously residual falcon colony. Pairs in this colony laid earlier and raised more fledglings than in the other established colonies. The specialization on petrels increased over time, independently of annual fluctuations in prey availability. Importantly, however, the positive effect of petrel consumption on productivity was stronger in years with lower food availability. This trophic diversification was further associated with the genetically-determined color morph, with dark individuals preying more frequently on petrels than pale ones, which might promote the long-term maintenance of genotypic and phenotypic diversity. We empirically demonstrate how the emergence of an alternative trophic strategy can buffer populations against harsh environmental fluctuations by stabilizing their productivity.

中文翻译：

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一种新的营养专业化可以缓冲顶级捕食者免受气候驱动的资源不稳定的影响

种内表型变异是应对环境变化和异常的关键。然而，由于难以在正确的时间和地点观察这种现象，记录自然群体中行为多样化的出现仍然难以实现。在这里，我们研究了在主要营养资源（迁徙鸣禽）可用性剧烈波动的种群中出现的新营养策略如何影响特殊颜色多态捕食者（即鸟类）的繁殖表现、种群结构和种群适应性。来自加那利群岛的埃莉奥诺拉猎鹰。使用长期数据（2007-2022），我们发现对替代猎物（当地海燕物种）的利用与先前残留的猎鹰群体的生长有关。与其他已建立的群体相比，这个群体中的成对产蛋时间更早，养育的雏鸟也更多。随着时间的推移，对海燕的专业化程度不断提高，与猎物供应量的年度波动无关。然而，重要的是，在粮食供应量较低的年份，海燕消费对生产力的积极影响更大。这种营养多样化进一步与基因决定的颜色形态相关，深色个体比浅色个体更频繁地捕食海燕，这可能促进基因型和表型多样性的长期维持。我们凭经验证明了替代营养策略的出现如何通过稳定种群的生产力来缓冲种群免受恶劣环境波动的影响。