Data from: Estimating resource preferences of a native bumble bee: the effects of availability and use-availability models on preference estimates

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.甄别资源偏好是制定靶向保护计划的必要前提，但针对多数物种而言，如何精准估算其资源偏好仍缺乏共识性方案。蜜蜂的资源偏好尤其难以确定，这是因为它们所采集的花蜜（nectar）与花粉（pollen）两类资源，其可获得性与实际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（inflorescence）为单位进行测算，但这类可获得性指标与蜜蜂实际利用的资源并不匹配。此外，现有纳入可获得性的通用模型是否适用于蜜蜂仍未明确——蜜蜂可能会优先选取特定资源，而不受该资源的可获得量影响。 本研究首先采用三类可获得性测算指标（花粉、花及花序），对两种常见的资源利用假说——随机利用假说("random use hypothesis")与线性偏好假说("linear preferences hypothesis")进行对比，以探究何种可获得性指标更适于阐释蜜蜂的花粉利用行为。随后，本研究将表现最优的可获得性模型，与一种全新的蜜蜂花粉利用模型——靶向利用假说("target use hypothesis")进行对比。该假说假定蜜蜂会优先选取特定资源，而不受该资源的可获得量影响（但前提是该资源存在于调查样地中），因此该模型无需依赖可获得性数据即可开展偏好建模。 在所有纳入可获得性的模型中，采用花序可获得性的线性偏好假说对花粉利用数据的阐释效果最佳。这表明熊蜂的花粉利用行为并非随机，且用于识别与定位资源的线索（即资源展示规模与数量），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，在多数情形下，靶向利用模型对数据的阐释效果优于或等同于其他模型，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，或许能更准确地刻画蜜蜂的资源利用行为。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。