Data from: Estimating resource preferences of a native bumblebee: the effects of availability and use-availability models on preference estimatess

Identifying resource preference is considered essential for developing targeted conservation plans but, for many species, questions remain about the best way to estimate preference. Resource preferences for bees are particularly difficult to determine as the resources they collect, nectar and pollen, are challenging to estimate availability and collection. Resources are traditionally measured at the flower or inflorescence level, but these measures of availability do not correspond to the resources actually used by bees. Additionally, it is unclear as to whether common models including availability are appropriate for bees which may target resources regardless of available quantities. Here we first compare two common hypotheses of resource use – the ‘random use hypothesis’ and the ‘linear preferences hypothesis’ – using three different measures of availability (pollen, flower and inflorescence) – to determine if one measure of availability was better for understanding bee pollen use. Next, the superior model using availability was compared to a novel model of bee pollen use the ‘target use hypothesis’. This model assumes that bees target some resources regardless of how much of each resource is available (but assuming resources are present at a site), and thus models preference without availability data. Of the models including availability, the linear preference model using inflorescence availability best explained the pollen use data. This suggests that bumblebee pollen use is non-random and that cues to identify and locate resources (i.e. display size and quantity) may be more important than the quantity of the resource available (i.e. pollen availability). Additionally, in most cases the target use model explained the data equal to or better than the other models suggesting bee resource use may be better modeled without measured availability data compared to linear models. These results could be important for expanding resource use analysis of bees that are difficult to quantify availability.明确资源偏好是制定针对性保护计划的核心前提，但针对多数物种而言，如何最优地估算其资源偏好仍存在诸多待解问题。蜂类的资源偏好尤其难以确定，因为它们采集的花蜜与花粉两类资源，其可获得性与采集量均难以精准估算。传统上，资源可获得性以单朵花或花序为单位进行测算，但这类可获得性指标与蜂类实际利用的资源并不匹配。此外，学界仍未明确：对于那些可能无视资源可获得量、主动靶向采集资源的蜂类而言，纳入可获得性变量的通用模型是否适用。本研究首先以三种不同的可获得性测算指标（花粉、单花、花序）为基础，对比两类常见的资源利用假说——“随机利用假说”与“线性偏好假说”，旨在探明哪一种可获得性指标更适合阐释蜂类的花粉利用行为。随后，本研究将表现最优的可获得性模型，与一种全新的蜂类花粉利用模型——“靶向利用假说”模型进行对比。该假说假定，蜂类会主动靶向特定资源，而不考虑该资源的可获得量（但前提是该资源在研究样地中存在），因此可在无需可获得性数据的前提下构建偏好模型。在所有纳入可获得性变量的模型中，以花序可获得性为测算指标的线性偏好模型，对花粉利用数据的解释度最高。这表明熊蜂的花粉利用并非随机行为，且用于识别与定位资源的线索（即资源展示规模与资源数量），或许比资源本身的可获得量（即花粉可获得性）更为关键。此外，在多数场景下，靶向利用模型对数据的解释度与其他模型持平甚至更优，这提示相较于线性模型，无需实测可获得性数据的资源利用模型，或许能更准确地模拟蜂类的资源利用行为。本研究结果对于拓展难以量化可获得性的蜂类资源利用分析具有重要参考价值。