The hierarchical model of provisioning posits that parents employ a strategic, sequential use of three provisioning tactics as offspring demand increases (e.g., due to increasing brood size and age). Namely, increasing delivery rate (reducing intervals between provisioning visits), expanding provisioned diet breadth, and adopting variance-sensitive provisioning. We evaluated this model in an Arctic breeding population of Peregrine falcons (Falco peregrinus tundrius) by analyzing changes in inter-visit-intervals (IVIs) and residual variance in IVIs across 7 study years. Data were collected using motion-sensitive nest camera images and analyzed using Bayesian mixed effect models. We found strong support for a decrease in IVIs (i.e., increase in delivery rates) between provisioning visits and an increase in residual variance in IVIs with increasing nestling age, consistent with the notion that peregrines shift to variance-prone provisioning strategies with increasing nestling demand. However, support for predictions made based on the hierarchical model of tactics for coping with increased brood demand was equivocal as we did not find evidence in support of expected covariances between random effects (i.e., between IVI to an average sized brood (intercept), change in IVI with brood demand (slope) or variance in IVI). Overall, our study provides important biological insights into how parents cope with increased brood demand.

中文翻译：

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游隼改变供应的均值和方差，以应对不断增长的育雏需求

供应的分层模型假设，随着后代需求的增加（例如，由于育雏规模和年龄的增加），父母会战略性地、顺序地使用三种供应策略。即，提高供应率（减少供应访问之间的间隔），扩大供应的饮食范围，并采用差异敏感的供应。我们通过分析 7 个研究年中访问间隔 (IVI) 的变化和 IVI 的残余方差，在北极游隼 (Falco peregrinus tundrius) 繁殖种群中评估了该模型。使用运动敏感巢相机图像收集数据，并使用贝叶斯混合效应模型进行分析。我们发现，有力支持了供给访问之间 IVI 的减少（即交付率的增加），以及随着雏鸟年龄的增加，IVI 的剩余差异增加，这与游隼随着雏鸟需求的增加而转向容易出现差异的供给策略的观点是一致的。 。然而，对基于应对增加的育雏需求的策略分层模型所做的预测的支持是模棱两可的，因为我们没有找到证据支持随机效应之间的预期协方差（即 IVI 与平均大小的育雏（截距）、变化之间的协方差）。 IVI 与育雏需求（斜率）或 IVI 方差）。总的来说，我们的研究为父母如何应对不断增加的育儿需求提供了重要的生物学见解。