|End of the line effect|
The concept of drifting is that with a number of hives in a row, on a windy day the bees are more apt to return to the first hive from the direction of the main pollen flow. Consequently the first hive will be much stronger than the last hive. Dave Cushman suggests the opposite "end of the line" effect (Dave Cushman on Drifting Behavior in Honey Bees). Dave goes on to describe the drifting effects of featureless water.
In any case the disoriented, drifting bees will have an unfamiliar smell to the guard bees but will usually be allowed entrance if carrying pollen and displaying submissive behavior. Ted Hooper in his book "Guide to Bees and Honey" states:
“a drifting bee entering the colony by mistake, perhaps because it has been blown down to the hive by a cross wind, or misled by a similarity of the approach picture, will be challenged. In this case the guard will press the challenge because the smell of this bee is not the right one. The drifter, because its instinct says it is in the right place, will not try to fight the guard but will submit. If the drifter is facing the guard it will offer food, which the guard will usually ignore. If the guard is attacking from the side [...] the drifter will tuck its tail in and stand quiet, with its head tucked down, or it may rear on to its two back pairs of legs, extending its tongue and strop this with its front legs. These patterns of behavior denote submission and the guard [...] will do no real harm and certainly not attempt to sting. As with all bees, the guard’s concentration period is short, and in a few seconds it gets tired of the whole affair and lets the drifter proceed”
This study found the percentage of drifting bees to be as high as 60% within unmarked row apiaries (Drifting of Honey Bee Foragers within and between apiaries pollinating blueberry) and up to 4.5% in apiaries 600 mts away. In the study below (Drifting of Honey Bees) they found that there was no preference in honey bee strain when drifting nor decrease in life span. They did find an increased drift from center (22%) to edge (39%).
|Hive setup that could lead to drifting|
The idea is that different colored hives will assist the bees in identifying their own hive. Bees see colors differently than we do and studies show they prefer purple, violet and blue in that order. Bees can see ultraviolet light patterns invisible to us (Honey Bees ability to identify color).
Why does drifting matter? Because unless you live in an isolated area there is a good chance your hives contain bees from neighboring hives along with their pests and diseases (Honey Bee Drifting and the spread of AFB). Drifting can also occur with Queens returning from mating flights (4% Honey Bee Queen Drifting).