It’s true that generally studies have found that in a ‘resource-rich’ region honeybees mostly forage within one kilometre of the nest (hive). The furthest distance I remember noted was 13.7km, but rarely does it exceed 2 – 3km. These ‘averages’ don’t really provide a reasonable picture of what happens in real life, and don’t really tell us much about mitigating the effect of poisonous sprays.
If we put to one side the physical environmental constraints on foraging, like daylight, temperature, precipitation, and wind, we can think of it in terms of supply and demand for all the things they forage for; nectar, pollen, water, and resins. Unlike other pollinators, honeybee foragers will be members of groups that tend to specialise in collecting each of these supplies, found in separate places and various distances from the hive. The demand for these things changes throughout the colony’s development, and big colonies (>20,000 bees) forage differently and more extensively than small colonies (<10,000 bees). For most of the summer the emphasis is on nectar, pollen, and water, in that order. The demand for pollen is fairly finite with only a kilo or two on hand per hive, the demand for nectar seems pretty infinite, into three figures with sufficient time and availability. Water is collected for cooling and consumption as required from the meniscus of usually still, shallow sources, drips, or seepage. Foraging for all the hive requirements can be carried out simultaneously by different groups of foraging bees in different places. Picture a busy international airport with multiple runways and aircraft leaving and arriving from different countries.
The resource supply is dynamic, complex, ephemeral, weather-dependant, and competitive. Honeybees are not the only consumers. For nectar and pollen scout bees and foragers will find and exploit many flower patches in an area of easily more than 1000ha, switching from one to another and back as the environmental conditions change and/or the resource becomes depleted or too competitive during the course of the day. Provided their home range is not too homogeneous foraging is well dispersed across space and in time. It would be true to say bees (all kinds) prefer ‘weedy’ species.
What can we do? Trying to work out where honeybees will be is more than tricky, and it’s not clear to me that advising beekeepers of spray intentions achieves very much. It clearly doesn’t do anything to protect any of the unmanaged foragers out there, all the complementary pollinators and pest controllers that provide the system resilience we mostly lack. Targeting application for when honeybees are not about is easier, but that comes with its own practical difficulties and still doesn’t address the problem of the unmanaged service providers. The usual mitigations, not on flowers, dawn or dusk, are limited, legal requirements, and Growsafe’s Best Practice lists
the necessary principles. Other than that, all we’ve got are better management systems and smarter chemical development.