Variations in Vocalization Frequency of Chachalacas in Chamela

Call of the Wild:
Variations in the Vocalizations of Western
Mexican Chachalacas in Chamela Jalisco,
Mexico
Julia VanDerslice
Emily Reyer
What We Were Investigating
 Frequency and duration of calls in relation to
time of day and habitat type
 Conducted over four days at the Estacion
Biologia de Chamela UNAM
 HA: The frequency of call will be different at
different times of day and in different habitat
types
 HA: The duration of calls will be different at
different times of day
Western Mexico Chachalaca
(Ortalis poliocephala)
 Large, chicken-like bird
 Frugivores
 Breeding season begins
in April
 2-3 eggs laid in June/
July and incubated by
mother
 Young have adult
plumage by six months
 No sexual dimorphism
(Hidalgo, 2002)
Mexican Tropical Dry Forest
 Dry season from
November to June
 One of the most
threatened habitat
types
250
200



Mean Temp. (C)
Rainfall (mm)
150

100
50
0



           
  
Jan Mar May Jul
Sep N Dec
ov
Images courtesy of Dr. Beck
Wet season photo courtesy of Dr.
Beck
Predictions
 Calling will be more frequent in the
morning
 More sightings/ vocalizations in the
arroyo
 Call duration will be highest in the
morning
(Caziani et al. 1994,
Brown et al. 2003)
Methods – Call Frequency
 Hiked Eje Central and
Tejón on three mornings
between 08:00 and
12:00
 Reversed direction every
day
 Calls constant in
morning
 Took 10min recording at
app. nearest point to a
group
 Noted the number of
groups and the habitat
type (arroyo vs. ridge)
 Could not discern the
number of individual
birds
Call Frequency (cont’d)
 Hiked in various areas in
afternoon between 15:30
and 19:00
 Approximately equal
time spent in arroyo and
on ridge
 Virtually no calls in
afternoon
 Noted sightings of birds
even when no calls were
heard
 Number of calls in each
recording was later
counted
Methods - Call Duration
 Observed calls for 30
min. periods
throughout mornings
and afternoons
 Recorded
approximate duration
of calls in seconds
Results
Frequency
1200
1400
1200
1000
Number of Calls
Number of Calls
1000
800
600
400
800
600
400
200
200
0
0
Arroyo
Ridge
Location
Figure 1 A bar graph showing the
number of chachalaca calls heard in the
morning (08:00-12:00) and in the
afternoon (15:00-19:00).
Morning
Afternoon
Time of Day
Figure 2 A bar graph showing the
number of chachalaca call heard in the
arroyo and on the ridge.
 Performed the Wilcoxon signed rank test for both data sets
 Time of Day (W = 19.5, p-value = 0.007)
 Location (W = 36, p-value = 0.036)
1000
900
Number of Calls
800
700
600
500
400
300
200
100
0
Arroyo Morning
Arroyo Afternoon
Ridge Morning
Ridge Afternoon
Conditions
Figure 3 A bar graph showing the number of calls heard
under each condition for time of day and location.
 Kruskal-Wallis one way analysis of variance
(Kruskal-Wallis chi-squared = 8.2889, df = 3, p-value = 0.040)
 Kruskal Wallis Multiple Comparisons Test
Results
Duration
0.3
0.4
0.35
0.25
0.3
Frequency
Frequency
0.2
0.15
0.25
0.2
0.15
0.1
0.1
0.05
0.05
0
0
1
2
3
4
5
7
8
9
10
11
12
1
13
0.35
0.14
0.3
0.12
0.25
0.1
0.2
0.15
0.05
0.02
0
0
3
09:30-10:10
4
5
6
7
8
Syllables per Call
4
5
9
10
11
12
13
6
7
8
9
10
11
12
13
9
10
11
12
13
Syllables per Call
0.06
0.04
2
3
0.08
0.1
1
2
09:10-09:40
Syllables per Call
Frequency
Frequency
08:40-09:10
6
1
2
3
10:25-10:55
4
5
6
7
8
Syllables per Call
Figure 4 Histograms showing the frequency of different call lengths during
half hour periods across the morning.
Number of Syllables per Call
14
12
Mean
10
Median
8
Min
6
Max
1st Quartile
4
3rd Quartile
2
0
08:40-09:10
09:10-09:40
09:30-10:00
10:25-10:55
Oberservation Period
Figure 5 A scatterplot showing the quartiles, median, minimum and
maximum values for syllables per call for the four observation periods.
 Performed the K-sample equality of medians
test
 Pearson chi2(3) = 17.7875 P < 0.0001
Discussion
 Statistically
significant results for
all test
 The Kruskal-Wallis
multiple comparison
test only showed a
true difference
between the arroyo
afternoon and ridge
morning
What are these birds
talking about?
 Staking out breeding territories
 Protecting food supplies
Our data does not support as calls were not heard all day
Does location of individual groups change over time?
 Courtship
Possible, need to observe birds actually calling and
determine if they were mated pairs
 Locating other groups after the night
Depends on the interacting between groups
 Is communicating intragroup or intergroup?
Acknowledgements
We would like to extend a special thank
you to Dr. Dan Beck and Dr. Lisa Ely as
well as to the staff at the Estacion Biologia
de Chamela UNAM for allowing us to live
and work there.
Literature Cited
 Gurrola Hidalgo MA. (2002) Historia Natural de Chamela. Instituto de
Biologia, UNAM. Mexico. pg. 331-335
 Caziani SM, Protomastro TJ. (1994) Diet of the Chaco Chachalaca.
The Wilson Bulletin 106(4):640-648
 Brown TJ, Handford P. (2003) Why birds sing at dawn: the role of
consistent song transmission. Ibis 145(1):120-129
 Moore RT, Medina DR. (1957) The Status of the Chachalacas of
Western Mexico. The Condor 59(4): 230-234
 Vaurie C. (1965) Systematic Notes on the Bird Family Cracidae No. 2
Relationships and Geographical Variation of Ortalis vetula, Ortalis
poliocephala and Ortalis leucogastra. American Museum Novitates
#2222
 Banks RC. (1990) Taxonomic Status of the Rufous-Bellied Chachalaca
(Ortalis wagleri). The Condor. 92(3): 749-753
 Orneles JF, Arizmendi M, Marquez-Valdelamar L, Navarijo M, Berlanga
HA. (1993) Variability Profiles for Line Transect Bird Censuses in a
Tropical Dry Forest in Mexico. The Condor. 95(2): 422-441.
 Davis IL. (1965) Acoustic Evidence of Relationship in Ortalis.
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