Ornithological Observations from Cocos Island, Costa
 Rica (April 2005)

 Robert Dean1 y Michel Montoya2

1 Bird Art, Monteverde, Costa Rica. robertdean@hotmail.com
2Cocos Island Scientific Adviser
 POBox: 6327-1000 San Jos, Costa Rica
 michelmontoya@correo.co.cr


Resumen
 Se presentan observaciones
sobre 33 species de la avifauna de la
Isla del Coco, Costa Rica, las que
fueron realizadas entire el 25 y 28 de
abril del 2005. Se anota el primer
registro para la Isla del Coco de
Hirundo pyrrhonota (Cliff Swallow /
Golondrina risquera), especie
migrant nertica.

Introduction
 The avifauna of Cocos Island is
comprised of 111 species included in
71 genera and 29 families. Of these
32 are pelagic species (15 genera), 39
shorebirds and waders (24 genera),
and 40 terrestrial (32 genera).
Thirteen species are breeding
residents, of which eight are pelagic
and five terrestrial including the three
species endemic to the island.
Ninety-eight migrant species are
recorded for Cocos Island and of
these 78 are Nearctic migrants of
various categories. Of the remaining
20 migrants, 15 are pelagics of wide
geographical distribution, four are
strictly Neotropical migrants, and one
domesticated (Columba livia)


(Montoya 2003 updated March 2005,
Montoya 2005, Montoya y Pascal
2005).
 As of yet the status of these
migrant species has not been
categorized, (ie. annual, occasional,
accidental, etc.), due to a lack of
systematic data on the avifauna of
Cocos Island. The lack of
information regarding dates of
sightings, interannual frequency,
numbers of individuals and other
pertinent data do not allow us a full
understanding of the avian dynamics
of this island territory.
 This article seeks to increase our
understanding of this island avifauna
while we await the implementation of
more systematic monitoring.
 These observations were
undertaken between 25 and 28 April
2005 while the authors were
participating in a program organized
by the Organization for Tropical
Studies (OTS), aboard the cruiseship
Pacific Explorer. They were made
while exploring the island's principal
trail system and during
circumnavigations in motorized
dinghies which allowed us to inspect