Scientists have shown that honey bees retain a memory of the dominant linear landscape features in their area of origin, such as canals, roads and boundaries.
When transported to an unknown area, they search for such local features, compare their path with memory, and fly along them to find their way back home. This navigation strategy is similar to the one followed by the first airmen.
In the early days of human flight, before the invention of the first ground-based electronic beacons and systems, and modern GPS, pilots used to navigate by following roads and railways, that is, following linear features of the landscape at ground level that guide to a destination of interest.
Honey bees are navigators par excellence. They can orient themselves by their sense of smell, the sun, the pattern of polarized light in the sky, vertical landmarks that jut out from the landscape, and possibly the Earth’s magnetic field.
A century of research has shown that honey bees are quintessential navigators. They can orient themselves by their nose, the sun, the pattern of polarized light in the sky, vertical landmarks that jut out from the landscape, and possibly the Earth’s magnetic field. They are also intelligent learners, able to recognize associations between disparate memories to generalize rules.
Now, scientists have shown that honey bees tend to find their way back home by orienting themselves in relation to the dominant linear features of the landscape, just like early pilots. The results are displayed in Frontiers in Behavioral Neuroscience (1).
“Navigation memory”
Dr Randolf Menzel, Professor Emeritus at the Department of Neurobiology at the Free University of Berlin and lead author of the study, explained: “Here we show that honey bees use a ‘browsing memory’, a kind of mental map of the area they know, to guide their search flights when searching for their hive starting in a new and unexplored area. The linear elements of the landscape, such as water channels, roads and edges of fields, appear to be important components of this navigational memory.”
Menzel and his colleagues captured 50 experienced foraging honey bees and they stuck a 10.5mg transponder on their back. Next, she released them into a new test area, too far away for the bees to know. In the test area there was a radar that could detect the transponders at a distance of up to 900 meters. The most notable landmark in the test area was a pair of parallel irrigation canals running southwest to northeast.
When bees find themselves in unfamiliar territory, they fly in exploratory circles in various directions and distances, centered on the release point. With the radar, the researchers followed the exact exploratory flight pattern of each bee for between 20 minutes and three hours. During the experiment, the bees flew up to nine meters above the ground.
During the experiment, the bees flew up to nine meters above the ground.
The researchers had collected collectors from five hives: the residence zone around hives A and B it resembled the test area in terms of the number, width, length and angle of linear landscape elements, especially irrigation canals. The home range around the hives D and E was very different in this aspect.or, while the home range around hive C had intermediate similarity with the test area. Other landmarks that honey bees have been known to find their way aroundsuch as structured horizons or protruding vertical elements, were absent in the test area.
Menzel et al. first simulated two sets of random flight patterns, centered on the release point and generated with different algorithms. Since the observed flight patterns were very different from these, the researchers concluded that the honey bees were not just making random search flights.
Next, the researchers used advanced statistics to analyze the orientation of the flights and their frequency of overflights of each 100 x 100 meter block within the test area. They showed that bees spent a disproportionate amount of time flying next to irrigation canals. The analyzes showed that these continued to guide exploratory flights even when the bees were more than 30 meters away, the maximum distance from which honey bees are able to see such landscape features. This implies that the bees kept them in their memory for long periods.
The bees kept a navigational memory of their home area, based on linear features of the landscape, and tried to generalize what they saw in the test area to their memory to find their way back home.
“Our data demonstrate that similarities and differences in the layout of linear landscape features between their home area and the new area are used by bees to explore where their hive might be,” Menzel says.
Importantly, the machine learning algorithms showed that the irrigation canals in the test area were the most informative for predicting exploratory flights of bees from hives A and B, less for bees from hive C, and less for bees. bees from hives D and E. This suggests that the bees maintained a navigational memory of their area of origin, based on linear features of the landscape, and attempted to generalize what they saw in the test area to their memory to find their way back home.
“Flying animals identify these types of extended terrain features in a map-like aerial view, making them very attractive as guide structures. It is therefore not surprising that both bats and birds use linear landmarks. to navigate. Based on the data presented here, we conclude that elongated soil structures are also prominent components of honey bee navigational memory,” the authors conclude.
References
- (1) Bees follow linear landmarks to find their way home, just like the first pilots. Frontiers in Behavioral Neuroscience.