ORIENTATION:
 
     I just signed onto BEE-L a little over a week ago and for a
while found the dialogue and information informative. Then one day
I had 36 new mail messages. wow! So now this is my chance to put a
note into the system on the topic of ORIENTATION.
     The original request by Southwick was for information on the
use of landmarks. Although I do not have any new information on the
bees use of landmarks ( orientation at a distance) I do have some
on the orientation in an apiary ( orientation near a goal - colony)
and what happens when colonies are moved.
     On a practical basis the latter situation is of most concern
to beekeepers. Young bees learn the position of their colony during
orientation flights. Bees that have never left their colony are not
able to return, if they are released more than about 50 metres
away. However, after repeated orientation flights they can find
their way home from a few kilometres. Beyond a distance of about 8
km or more no bees will return (Wolf 1927, Uchida & Kuwabara 1951,
Becker 1958).
     If there is disorientation at a distance the bees become lost.
If there is disorientation near the goal the bees drift and end up
in a different colony. When colonies are placed in similar
arrangements, bees often confuse their colony with another. This is
especially true if the strange colony occupies the same position in
another group i.e. the end colony of a row (Free 1958, Mathis
1960). Jay showed that when colonies are in rows, bees drift from
the back row to the front and to the ends of each row.
     Bees of a colony remember which side the colony entrance is on
(Free & Spencer-Booth 1961). Thus, if the colony is rotated 90
degrees or more the bees will try to get into the original entrance
location for some considerable time. Likewise, if the entrance
height is changed the bees will continue to try and enter at the
original position. The confusion can last a couple of days. This
situation can often be seen in the spring (in our area) when
colonies are wintered outside and bees have been using the top
entrance. Then we come along and remove the black winter wraps
(change in colour as well) and take away the top entrance (change
in location). Both of these situations will lead to considerable
confusion for about 2-3 day.
     Drifting is a real problem in commercial apiaries (Jay 1965,
1966, 1968, 1969) and many of the well known considerations of
coloured boards, off-set entrances, irregular arrangements of
colonies, distance between colonies, queen state, etc. all have an
influence on the amount of drift that occurs.
     The effect of moving and transporting bees on disorientation
and bees loss (Nelson, Apidologie 1989) showed bee losses of up to
45% for colonies moved to a new apiary site 14 km distant, and
drifting of up to 38%.
 
     The use of orientation cues (coloured board and tree branches)
did not significantly reduce bee losses, and in fact the tree
branches increased drifting (Nelson Thesis 1985). I think the use
of tree branches makes the beekeeper feel better and certainly
causes the bees to hesitate and maybe do some play flights at the
colony entrance, but don't appear to help the bees orient to the
colony. Coloured boards were about the same as no cue. Some of
these apply mainly to bees 21 days old. With younger bees the loss
and drift is usually less. The best situation is to only place two
hives near each other. Can the bees only count to two or do they
know their left from their right?
     A couple of papers on sun orientation (Jay, Can. Entomol. 1971
and Jay & Warr, J. apic Res. 1984) may be of interest to some of
you. Rob Currie has done several studies the last 6 years on drone
loss and drift with a good review is in 1987 Bee World 68,129-143.
     Is anyone interested in drifting studies as it may relate to
the spread of HBTM or varroa? I plan to start a study next spring.
 
Don Nelson   [log in to unmask]
               Research Branch, Beaverlodge, ALBERTA