Saddleback Journal of Biology - Saddleback College

Spring 2010 Biology 3B Paper
20
Number of Corvids
15
10
5
0
Morning
Afternoon
Time of Day
Figure 1. Number of successful responses observed in C. Americanus during the morning and afternoon. Total
number of trials for each set, n=45. (p=0.0088, Chi-squared 2x2 two tailed contingency test)
Discussion
The purpose of this study was to determine
what factors affected the number of responses in the
American Crow, specifically, the time of day. The
results were in accordance with previous research
done on the response rate of corvids. The four
experiments reported here have shown that one can
alter the assembly power of natural crow caws
(Thompson ,1982). Although few studies have been
done to test the correlation between the number of
responses and the time of day, the results show the
same type of variation found in previous studies. In
the past, researches have had results that drastically
differ on a daily basis. Variability of distress calls
within the species is considered a likely explanation
for these results (Bremond et al, 1968). Even though
there was a significantly larger amount of responses
in the afternoon than the morning, the response rates
seemed to also show a variance by location. Three
locations were used for research and all three were on
the Saddleback College campus. All the locations
were presented with the same number of calls and the
same number of trials per day, but lot-1 had a higher
response rate compared to the other locations.
Corvids tend to nest between March and May, so it is
possible that calls closer to nests would have a higher
response rate. As a continuation of this study,
researchers are encouraged to explore any correlation
between nest proximity and response rates.
Literature Cited
Barash, P. (1976). Mobbing behavior by Crows: The
Effect of the Crow in Distress Model. The Condor
78: 120
Bremond, J., Gramet, P., Brough, T. and Wright, E.
(1968). A Comparison of Some Broadcasting
Equipments and Recorded Distress Calls for Scaring
Birds. Journal of Applied Ecology 5: 521-529
Burns, L. (1901). Crow Language. The Wilson
Bulletin 13: 5-9
Johnston, D. W. (1961). The biosystematics of
American crows 8: 27
Thompson, N. S. (1982). A Comparison of Cawing in
the European Carrion Crow (Corvuscorone) and the
American Common Crow (Corvus brachyrhynchos).
Behavior 80: 106-117.
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Saddleback Journal of Biology
Spring 2010