You would think this would be a no-brainer, and that bees would obviously prefer living in the countryside, with the wide variety of both food and nesting options.
But a recent study comparing rural honeybees with urban honeybees, found that rural bees were flying on average 50% further than their city-based colleagues, to fetch food.
So why would bees in the countryside need to fly further to find food?
As an aside, in case you were wondering, they calculated the average flight distances of bees using video analysis of the bees’ waggle dances. When scout bees return to the hive, they perform a waggle dance to tell their colleagues how to locate the food source they have found. The duration of the ‘waggle’ indicates the distance, and this can be measured by analysing the video from inside the hive, and calibrated using the distance to known food sources.
So how do we explain the variance in flight distance between urban and rural bees?
The lifespan of a worker bee is measured in air miles, so bees are highly motivated to constantly optimise their flying time. This means they would only fly further if it was necessary.
One possibility was that the bees in the countryside were flying further to access richer food sources. Bees will intelligently balance distance with food quality, so might decide to fly further for richer food sources. But subsequent analysis of the nectar being collected suggested that the quality of food was similar, so the variance can’t be explained by a difference in food quality.
Further analysis of the landscapes showed that while urban areas include lots of areas that provide very little food for bees, like roads and buildings, they also include gardens and parks, which provide a rich variety of flowers for bees. Rural areas on the other hand, are often dominated by farms, and while farms do provide hedges, woodlands, and wild areas, they consist mainly of large fields of single crops. And these large fields don’t provide many varieties for bees.
The bigger the fields, the smaller the plant diversity, so the worse this problem becomes.
There is also the potential issue of pesticides. Another study showed that new bee colonies in urban areas were on average healthier than new bee colonies in rural areas, and one possible explanation is that this is due to the negative impacts of pesticides on bee health.
So, while urbanisation clearly causes problems for bees due to the loss of bee habitats, it looks like modern agricultural practices might also be a cause for concern.
