1. One of the major challenges faced by pollinators worldwide is the reduction in their food supply, nectar, and pollen. Given the considerable seasonal variation in the abundance of both floral resources and flower‐visiting insects, conservation initiatives aiming to help pollinators through floral resource supplementation could increase their impacts by targeting periods when the foraging conditions are most difficult. Direct assessment of foraging conditions, however, is extremely labour‐intensive.
2. Here, we compared eight practical measures expected to reflect the foraging difficulty for nectar in the environment. Five measures involved Apis mellifera – an indicator species for the flower‐visitor guild due to its generalist, energetically optimal, and long‐distance foraging habit. These included (i) visitation at feeders with a range of sucrose concentrations, (ii) guarding and (iii) fighting levels at hive entrances, (iv) rates of hive weight changes, and (v) foraging distances encoded in waggle dances. The other measures were (vi–viii) counts of flower‐visiting insects in relation to the rate of nectar sugar secretion in three plant species attractive to flower‐visiting insects.
3. There was considerable, although not complete agreement among the eight measures. Eleven of 28 pairwise correlations were statistically significant. Guarding and fighting correlated with most (five) other measures. We conclude that seven of the eight measures could be potentially useful in gauging seasonal patterns in local foraging conditions, which could help guide targeted conservation initiatives. Assessment of guarding and fighting levels at A. mellifera hive entrances is recommended, as these correlated significantly with most other measures and are easy to obtain in practice.

中文翻译：

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评估花蜜觅食条件的多种方法表明后期觅食困难高峰

1. 全世界授粉媒介面临的主要挑战之一是减少其食物供应，花蜜和花粉。鉴于花卉资源和访花昆虫的丰富性在季节性上有很大差异，旨在通过补充花卉资源帮助传粉媒介的保护措施可以通过针对最困难的觅食条件时期来增加其影响。但是，直接评估觅食条件非常费力。
2. 在这里，我们比较了预期可反映环境中花蜜觅食难度的八种实用措施。蜜蜂（Apis mellifera）是五种措施之一，因为它具有通才，精力充沛的最佳选择和远距离觅食的习性，因此是花卉访问者协会的指示物种。其中包括（i）在蔗糖浓度范围内的饲养者处探视；（ii）蜂巢入口处的防护和（iii）战斗水平；（iv）蜂巢重量变化率；以及（v）摇摆舞中编码的觅食距离。其他措施是（vi–viii）访花昆虫与三种对访花昆虫有吸引力的植物的花蜜糖分泌速率相关的计数。
3. 八项措施之间达成了相当大的共识，尽管尚未完全达成共识。28个成对的相关性中有11个具有统计学意义。保卫和战斗与大多数其他（五项）措施有关。我们得出的结论是，八项措施中的七项可能在衡量当地觅食条件下的季节性模式方面可能会有用，这可能有助于指导有针对性的保护举措。建议评估A. mellifera蜂巢入口的防护和战斗水平，因为它们与大多数其他措施显着相关，并且在实践中很容易获得。