SHORT COMMUNICATIONS 
613 
SAS Institute Inc. 2009. JMP 8.0.1 Statistical discovery 
software. Cary, North Carolina, USA. 
Smith. L. C.. S, A. Raouf, M. B. Brown, J. C. Wingfield, 
and C. R. Brown. 2005. Testosterone and group size 
in Cliff Swallows: testing the “challenge hypothesis" 
in a colonial bird. Hormones and Behavior 47:76-82. 
Stltchbury, B J. and R. J. Robertson. 1987. Two 
methods of sexing adult Tree Swallows before they 
begin breeding. Journal of Field Ornithology 58:236- 
242 , 
Van Duyse, E., R. Pinxten, .and M. Eens. 2000. Does 
testosterone affect the trade-off between investment in 
sexual/tenitorial hehavior and parental can: in male 
Great Tits? Behaviour 137:1503-1515. 
Van Roo. B. L„ E. D. Ketterson, and P. J. Sharp. 2003. 
Testosterone and prolactin in two songbirds that differ 
in paternal care: the Blue-headed Virco and the Red¬ 
eyed Vireo. Hormones and Behavior 44:435-441. 
Veiga, J. P. ano V. Polo. 2008. Fitness consequences of 
increased testosterone levels in female Spotless 
Starlings. American Naturalist 172:42-53. 
Vleck, C. M. and D. Vleck. 2010. Hormones and 
regulation of parental behavior in birds. Pages 181 — 
203 in Hormones and reproduction of vertebrates (D. 
O. Norris and K. H. Lopez, Editors), Volume 4. Birds. 
Elsevier Press, San Diego, California, USA. 
Wingfield, J. C.. R. E. Hkgnkr, A. M. Duety Jr., and G. 
F. Ball. 1990. The "challenge hypothesis": theoret¬ 
ical implications for patterns of testosterone secretion, 
mating systems, and breeding strategics. American 
Naturalist 136:829-846. 
Winkler, D. W. 1992. Causes and consequences of 
variation in parental defense behavior by Tree 
Swallows. Condor 94:502-520, 
Woodley, S, K. and M. C. Moore. 1999. Female 
territorial aggression and steroid hormones in 
mountain spiny lizards. Animal Behaviour 57:1083- 
1089. 
ZaCH. R. 1982. Hatching asynchrony, egg size, growth, and 
Hedging in Tree Swallows. Auk 99:695-700. 
Zysling, D. A.. T. J. GreIves, C. W. Breunfr, J. M. 
Casto, G. E. Df.mas. and E. D. Ketterson. 2006. 
Behavioral and physiological responses to experimen¬ 
tally elevated testosterone in female Dark-eyed Juncos 
(Junco hyemalis carolinensis). Hormones and Behav¬ 
ior 50:200-207. 
The Wilson Journal of Ornithology 123(3):613-618, 2011 
First Description of the Breeding Chronology of the White-collared Swift 
{Streptoprocne zonaris) in Argentina 
Julieta M. Passeggi 1,2 
ABSTRACT.—Nesting activity of the White-col¬ 
lared Swift (Streptoprocne zonaris) was monitored from 
October 2001 to March 2002 to describe the breeding 
chronology of this species. Data were obtained from the 
colony ‘La Cueva de Ins Pajaritos'. near Mallm, 
Cordoba. Argentina. These arc the first descriptions of 
bie nesting chronology of this species in Argentina. The 
Reding season lasted 81 days from egg laying in early 
November to fledging in middle to late January. Clutch 
s,ze ranged from one to two eggs which were incubated 
for an average of 22 days. Nestlings remained in nests 
for an average of 44 days and fledglings remained at the 
Mte for -5 additional days. These observations provide 
new information on nesting sites used by S. zonaris in 
Argentina, and provide the first documentation of the 
length of the breeding phases for the species in South 
Faeultad dc Humanidades y Ciencias, Pje El Pozo. 
( iudad Univcrsitaria, Universidad Nacional del Litoral. 
fPJOOO Santa Fe. Argentina. 
Current address: Dcpartamento dc Ffsiea. Faeultad dc 
‘ngenieria Quimica. Santiago del F.stcro 2829, Universidad 
National del Litoral. CP3000 Santa Fe. Argentina; 
Entail: julictapasseggi@gmail.com 
America. The ‘apparently shortened’ length of incuba¬ 
tion and nestling periods may be a geographical effect, 
due to this being the most southeastern known breeding 
colony for S. zonaris. Received 6 July 2010. Accepted 7 
February 2011. 
Swifts (Apodidae) are difficult to observe and 
identify in the field. Access to nesting sites is 
usually complicated, and large gaps exist in our 
knowledge about the biology of many species 
(Whitacre 1989, Mann and Stiles 1992). The 
White-collared Swift (Streptoprocne zonaris ) is in 
the subfamily Cypseloidinae that comprises 13 
species of tropical swifts (Lack 1956. Sibley and 
Monroe 1990. Chantler and Driessens 1995, 
Chantler 1999, Mario 1999), This species occurs 
in Mexico, Central America, South America, and 
the Caribbean (Beebe 1949, Rowley and Orr 
1965, Whitacre 1989), 
Neotropical swifts breed early in the rainy 
season, coinciding with the peak of flying insects 
