Data from: The scope and adaptive value of modulating aggression across breeding stages: Case study in a competitive female songbird

<p><span><span>In seasonally breeding animals, costs and benefits of territorial aggression should vary over time; however, little work thus far has directly examined the scope and adaptive value of individual-level plasticity in aggression across breeding stages. We explore these issues using </span><span>the tree swallow (</span></span><em><span><span>Tachycineta bicolor</span></span></em><span><span>), a bird species in which females compete for limited nesting sites</span> <span>before producing a single brood. We measured the aggressiveness of nearly 100 females within three different stages: (1) shortly after territory-establishment, (2) during early incubation, and (3) while caring for young chicks. </span></span><span><span>We used k-means clustering to categorize females into four distinct plasticity 'types' based on the timing, direction, and magnitude of their changes in aggression between stages. We then tested whether plasticity type and stage-specific aggression </span><span>vary</span><span> with </span><span>key</span><span> performance metrics.</span></span><span><span> Two of the four</span> <span>plasticity</span><span> types became less aggressive </span><span>across consecutive breeding stages</span><span>, consistent with population-level patterns, though these plasticity types </span><span>largely </span><span>did not differ from one another in survival or reproductive success</span></span><span><span>. A third type was characterized by high levels of among-stage plasticity</span><span>; </span><span>these females</span><span>, </span><span>had </span><span>significantly </span><span>lower body mass while parenting, </span><span>tended to hatch fewer eggs,</span> <span>and </span><span>had the lowest observed </span><span>overwinter survival </span><span>rates</span><span>. </span><span>A final type exhibited </span><span>limited</span><span> plasticity, with moderate to low levels of aggression </span><span>in all stages; </span><span>this low plasticity </span><span>-</span><span> low aggression phenotype</span><span> was not associated </span><span>with any </span><span>negative</span> <span>effects to </span><span>performance</span><span>.</span> <span>These</span><span> results reveal substantial among-individual variation in behavioral plasticity, which may reflect diverse solutions to trade-offs between current reproduction and future survival.</span></span></p>