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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 124. No. 3. September 2012 
TABLE 1. Distance (m) between territories (upper half) of eight male Turdus grayi (A-H) and number of shared 
syllables between males (lower half) during the 2008 breeding season in San Jose. Costa Rica. Male syllable repertoire size 
is shown in parenthesis. 
Male 
A (12) 
B (II) 
C (14) 
D (13) 
E (10) 
F (17) 
G (12) 
H (17) 
A 
55 
149 
209 
271 
32 
135 
125 
B 
0 
_ 
96 
181 
325 
29 
84 
75 
c 
0 
0 
_ 
140 
420 
118 
68 
33 
D 
2 
0 
1 
— 
452 
181 
205 
124 
E 
1 
0 
1 
1 
— 
303 
394 
395 
F 
1 
0 
2 
1 
1 
— 
113 
93 
G 
0 
0 
1 
0 
0 
0 
— 
82 
H 
1 
0 
3 
1 
0 
0 
0 
— 
Totals 3 
4 
0 
7 
5 
2 
4 
1 
5 
" Tolal number of different shared syllable types. A male may share the same syllable type with more than one other male. 
DISCUSSION 
Songs of Clay-colored Thrushes are highly 
variable in length and number of syllables within 
and between males. Variation between males in 
song length and syllable number could be the 
result of individual differences in neuromuscular 
development that constrain song duration and 
performance (Lambrechts 1996, Suthers et al. 
1999). For example, male Zebra Finches (Taenio- 
pygia guttata) with longer and more complex 
songs have greater reproductive success (Wood- 
gate et al. 2012). Thus, song length and syllable 
number are traits that could provide females with 
valuable information regarding male quality. In 
turn, variation in song length (Weary et al. 1988) 
and song tempo (Cooper and Goller 2006) within 
males could be affected by the motivational slate 
of the singing bird. However, song tempo in our 
study was considerably steady. 
Male Clay-colored Thrushes have a repertoire 
of 10-17 syllable types. This repertoire size is 
within the range that has been observed for other 
thrushes of the genus Tardus, which have 
repertoires composed of 6 to 25 syllable types 
Number of recorded syllables 
breech n e' season* San inlfr Kp *™ ire s jf ^ number of recorded syllables of Clay-colored Thrushes during the 2001 
breeding season m San Jose. Costa Rica. The solid gray line indicates mean repertoire size = 13 syllable types (« = 
