180 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 1, March 2011 
subbuteo) were considered and rejected as candi¬ 
dates during the initial viewing. Bat Falcon would 
be most likely having been recorded as a vagrant 
to Grenada (Raffaele et al. 1998). The Bat Falcon, 
a species I have seen multiple times in Venezuela 
and Mexico, is smaller with a shorter tail and full 
dark hood, the latter character especially being 
quite different from the distinctive facial pattern 
of the Aplomado Falcon. The bird was first seen 
perched on a dead tree that a Peregrine Falcon had 
been frequenting. It appeared slightly smaller than 
a Peregrine Falcon, therefore much too large to be 
a Bat Falcon. The distinct black vest, combined 
with the light superciliary stripe and dark facial 
markings, clinched the identification. The long, 
banded tail was observed well during the bird’s 
preening, a character with which I had been 
particularly impressed while previously observing 
Aplomado Falcons in Venezuela. Australian 
Hobby (F. longipennis ) can be eliminated due to 
lacking a dark vest and not showing a complete 
superciliary stripe (Ferguson-Lees and Christie 
2005). In addition, its range is geographically 
distant from Puerto Rico. Lanner Falcon (F 
biarmicus ), similarly unlikely based on range, 
can also be eliminated by lack of a dark vest' 
shorter tail, and less distinct superciliary stripe 
when present (Ferguson-Less and Christie 2005). 
There are three subspecies of Aplomado 
Falcon; F. femoralis septentrionalis and F. 
femoralis femoralis are geographically the best 
candidates for a vagrant to Puerto Rico. The other 
subspecies, F. f pinchinchae , is geographically 
distant and shows a much richer rufous coloration 
than the bird observed. The nominate subspecies 
is geographically the closest to Puerto Rico. 
I was able to observe the falcon for -8 hrs over 
5 days. It was perched on fence posts or small 
trees (<7 m tall) for the majority of this time. Its 
observed hunting style was similar to a female 
Merlin that I observed daily at the lagoon. This 
Merlin successfully captured dragonflies, and the 
Aplomado Falcon’s prey items were assumed to 
be similar. However, no specific prey items were 
identified. 
This species is rare in Central America south of 
Mexico. It was first recorded in Honduras and 
Costa Rica during the last 30 years (Koford et al. 
1980, Marcus 1983). It is rare in Trinidad, 
although breeding has been recorded (ffrench 
and ffrench 1966, ffrench 1991). The closest 
stable breeding population is in Venezuela, 
—800 km south of Puerto Rico. 
ACKNOWLEDGMENTS 
I thank many Puerto Rican birders for sharing their 
sightings with me, especially during the period after I left. 
Sergio Colon, Mike Morel, Manuel Cruz, and Fred 
Schaffner all communicated sightings and misses toward 
the end of the falcon's stay. I also thank the National 
Geographic Society Committee for Research and Explora¬ 
tion (Grant #8261-07), for providing all of the funding for 
my research in Puerto Rico. My advisor, J. L. Lockwood, 
was instrumental in encouraging my work in Puerto Rico. 
LITERATURE CITED 
Ferguson-Lees, J. and D. A. Christie. 2005. Raptors of 
the world. Princeton University Press, Princeton, New 
Jersey, USA. 
ffrench, R. 1991. A guide to the birds of Trinidad and 
Tobago. Second Edition. Cornell University Press, 
New York, USA. 
ffrench, R. P. and M. ffrench. 1966. Recent records of 
birds in Trinidad and Tobago. Wilson Bulletin 78:5— 
11 . 
Keddy-Hector, D. P. 2000. Aplomado Falcon (Falco 
femoralis). The birds of North America. Number 549. 
Koford, R. R.. g. S. Wilkinson, and B. S. Bowen. 1980. 
First record of an Aplomado Falcon (Falco femoralis) 
in Costa Rica. Brenesia 17:23-25. 
Marcus, M. J. 1983. Additions to the avifauna of 
Honduras. Auk 100:621-629. 
Raffaele, H., J. W. Wiley, O. Garrido, A. Keith, and J. 
Raffaele. 1998. A guide to the birds of the West 
Indies. Princeton University Press, Princeton. New 
Jersey, USA. 
