First published online November 14, 2008
Journal of Experimental Biology 211, 3729-3736 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.022970
The connection between landscapes and the solar ephemeris in honeybees
William F. Towne* and
Heather Moscrip
Department of Biology, Kutztown University of Pennsylvania, Kutztown, PA
19530, USA
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Fig. 1. Aerial views of the natal site (A) and test site (B) for the 2007
experiments. The hive (H) was placed in corresponding locations along sloping
treelines at the two sites. The feeder at the natal site A was always directly
beside the hive, and the feeders at the test site B were moved toward
F1 (white arrow 140 m northward from the hive) and F2
(white arrow 110 m eastward) in the first and second trials of the experiment,
respectively. The broken lines at the natal site (F1 and
F2 in A) indicate the fictive locations of the feeders in the two
trials. That is, there were actually never feeders there, but these were the
predicted dance directions for bees using a memory of the sun's course in
relation to the natal site under clouds at the test site in the first and
second trials, respectively. North is indicated by the black arrowhead in B.
Adjacent contour lines in both figures are separated by 6.1 m of elevation.
The natal site A is at 75 deg. 46'10.5''W, 40 deg.
36'27.9''N; and the test site B is at 75 deg.
47'10.2''W, 40 deg. 37'12.9''N. Photos by the United
States Geological Survey, courtesy of the USGS and TerraServer-USA.
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Fig. 2. Views of the hive (white object left of center) in place at the natal site
(A, photo facing south-southeast) and test site (B, photo facing
north-northwest). The landmarks and topographies of the two sites were
similar, including valleys and then distant ridges in the directions opposite
from the views shown here. Photos by the authors.
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Fig. 3. Dance indications of bees under overcast skies at the test site on 10
August 2007. The bees had no route training at the natal site
(Fig. 1A;
Fig. 2A), and the hive was
transplanted to the test site (Fig.
1B; Fig. 2B) and
the feeder moved away from the hive toward the north-northwest
(Fig. 1B, arrow labeled
F1) under overcast skies. Times are given in local solar time
(LST). Each symbol represents the visual average of at least five wagging runs
during a single bout of dancing by one bee; each bee was scored only once
after a single trip to the feeder. The direction to the feeder, and thus the
correct dance indication for the test site, was 353.5 deg. (horizontal gray
line marked `Test site'). The predicted direction for dances oriented by
memory of the sun's course relative to the natal site (broken line toward
F1 in Fig. 1A) was
165 deg. (horizontal black line marked `Natal site'). The sun first appeared
this day at 08:04 h, indicated by a thin vertical line. Gray symbols connected
by broken vertical lines show bimodal dances (see text). The sky bar above the
graph shows the sky conditions: black indicates complete overcast; white
indicates that we could detect the sun. There were no periods of blue sky
without sun. CW; clockwise.
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Fig. 4. Dance indications of bees under overcast skies at the test site on 16
August 2007. The hive was transplanted to the test site
(Fig. 1B;
Fig. 2B) and opened under
overcast skies, and the feeder was moved away from the hive, this time toward
the east (Fig. 1B,
F2). The direction to the feeder, and thus the correct dance
indication was 85 deg. (horizontal gray line marked `Test site'). The
predicted direction for dances oriented by memory of the sun's course relative
to the natal site (Fig. 1A,
broken line toward F2) was 260 deg. (horizontal black line marked
`Natal site'). One of the 22 bees performed two disoriented dances (gray
symbols on the lower axis). All other symbols and conventions as in
Fig. 3.
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Fig. 5. Aerial views of the home site (A) and test site (B) for the valley floor
experiment. The locations of the hive are indicated with white dots labeled H.
Both sites were at the bottom of valleys (adjacent contour lines are separated
by 6.1 m of elevation) but the landmarks at the two sites were quite different
(see also Fig. 6). The bees
were given no route training at the home site and were then transplanted to
the test site under overcast skies, after which the feeder was moved toward
the west (white arrow marked F in B, which is 200 m long). The direction that
the bees indicated in their dances (Fig.
7) was roughly opposite the correct direction for the test site
and is shown here relative to the home site A by the broken line marked D. The
home site A is at 75 deg. 47'43.4''W, 40 deg.
36'41.4''N; and the test site B is at 75 deg.
47'18.8''W, 40 deg. 37'9.6''N. Photos by the United
States Geological Survey, courtesy of the USGS and TerraServer-USA.
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Fig. 6. 360 deg. panoramic views of the home site (A) and test site (B) for the
valley floor experiment. The two views are more or less oppositely oriented;
that is, the center of the panorama is roughly south in A and north in B,
which best represents how the bees matched the sites. The location of the hive
at each site is indicated with a white dot labeled H. The direction indicated
by the bees' dances (D) relative to the home site corresponds to the direction
of the feeder (F) at the test site. That is, under overcast skies, the bees
mistook the test site for the home site and set their dance angles accordingly
(Fig. 7). The photos were taken
at corresponding locations 45 m from the hive along the line toward the feeder
(test site) or toward the direction indicated by the dances (home site). Note
that the skylines of the two sites match closely, especially when one ignores
the many trees in the foreground at the home site A (see also
Fig. 5).
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Fig. 7. Dance indications of bees that had been transplanted from their home on the
floor of one valley (Fig. 5A;
Fig. 6A) to the floor of
another (Fig. 5B;
Fig. 6B) under overcast skies.
The bees had no training at the first valley, and they were marked at the
newly established feeder on the day of the test. The correct dance direction
for the test site was 262.5 deg. (horizontal black line) but the bees danced
in roughly the opposite direction (mean 75 deg.), indicating that they mistook
the test valley (Fig. 5B;
Fig. 6B) for their home valley
(Fig. 5A;
Fig. 6A) and danced by memory
of the sun's course in relation to the latter. The feeder was 100–200 m
from the hive during the recordings. All other symbols and conventions as in
Figs 3 and
4.
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© The Company of Biologists Ltd 2008
