Saddleback Journal of Biology - Saddleback College

Fall 2009 Biology 3B Paper
Number of Seeds Eaten
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Color of Seed
Figure 1. Bar graph displaying the number of seeds
eaten for individual colors. Contingency table analysis
for ordinal categories showed a significant difference
between both the number of safflower seeds eaten and
number of seeds that remained due to
p-value < 0.00001.
Discussion
The results show that there was a significant
difference between the tan (non-dyed) seeds and the
red, blue, yellow, and green seeds. The tan (non-dyed)
seed was preferred above the other colors with
significant difference disproving our expectations of
dyed seeds being favored.
Captive vs. Non-Captive
Tendencies of color preference in captive birds may
be different from that of wild birds. Baskett and
Goforth (1971) indicated that their penned mourning
doves preferred seeds with a blue background over
other colors. However, Avery and his colleagues
(1999) found that their captive Red-Winged Blackbirds
and Boat-Tailed Grackles preferred the lighter colored
natural seed. Cromie, etal. (1993) tested the influence
of fruit color on feeding of preferences of captive
American Robins. They found surprising results
showing that blue colored fruit was favored over their
traditionally eaten red fruit. Due to the fact that these
birds were captive they may prefer feed that is beyond
their usual preferences.
Non-captive birds such as in Pank’s (1976)
experiment showed that birds avoided treated seeds and
preferred the original seeds. However Frank and Mary
Slaby (1977) indicated that Steller’s Jays preferred red
colored peanuts over other colors. The variance in
color preference is most likely different among
different bird species as shown by these two tests. To
further our experiment we would repeat this
experiment over a longer period of time. This would
allow local birds to become adapted to the designated
food source and possibly change their typical feeding
habits.
Ultraviolet Light
Based on Parish et. al (1984), the vision of many
avian species comes very close to ultraviolet (UV)
wavelengths, which is a part of natural sunlight. Birds
use this UV light for behaviors such as reproduction,
foraging for food, and signaling. Butler (2005) showed
that parakeets distinguish a violet training light from
light made up of mixtures of blue and UV. When the
mixture had only about 8 percent UV, it matched the
hue of the training light and the birds made many
errors showing the birds perception of UV light. Also,
Cuthill and Stevens (2007) studied that class aves use
UV reflecting signals in choosing mates. This led to the
proposal that UV signals in birds may represent private
channels of communication hidden from predators,
because most mammalian predators of birds are
unlikely to see UV light. To expand on these studies,
experimentation on preference of UV light on seed
preference amongst the avian species can be
conducted.
Acknowledgements
We would like to thank Professor S. Teh for his
helpful comments and encouragement, without which
this project would have never seen completion. We
would also like to thank Mr. and Mrs. Kouyoumdjian
for their help in funding the experiment and for setting
up the location. Because of their help, everything was
able to be carried out smoothly.
Literature Cited
Avery, Michael L.; Decker, David G.; Humphrey, John
S.; McGrane, Arlene P. 1999. Seed Color Avoidance
by Captive Red-Winged Blackbirds and Boat-Tailed
Grackles. The Journal of Wildlife Management, Vol 63,
No. 3,1003-1008
Baskett, Thomas S.; Goforth, W. Reid. 1971. Effects of
Colored Backgrounds on Food Selection by Penned
Mourning Doves (Zenaidura macroura). The Auk, Vol
88, No. 2, 256-263
Butler, Byron; Goldsmith, K. Timothy H. 2005.Color
Vision of the Budgerigar (Melopsittacus undulatus):
Hue Matches, Tetrachromacy, and Intensity
Discrimination. Journal of Comparative Physiology,
Vol. 191, No. 10, 933–951
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Saddleback Journal of Biology
Spring 2010