| Learning More About Orange-crowned Warblers
 The Orange-crowned
Warbler (Vermivora celata) breeds widely over western and northern North America,
and east across Canada. There are four recognized subspecies of this warbler.
One of them, the sordida subspecies (Vermivora celata ssp.sordida), is endemic
to the Channel Islands and reaches its highest density on Santa Catalina Island.
This subspecies is fairly different from others that breed on the continent,
however, its life history is poorly known. While mainland Orange-crowned Warblers
are long distance migrants and strict ground nesters, the sordidas are year round
residents on the islands or migrate a very short distance to the coast of Southern
California and nest in shrubs or trees as well as on the ground.
In March 2003, researchers from the Smithsonian Migratory Bird Center and
the University of California at Riverside began a long-term study on Santa Catalina
Island to better understand the life history and ecology of this warbler. One
hundred individuals including males, females and nestlings were captured and
banded. This banded population will allow determination of which proportion of
the population stays year round or leaves the island during the fall.
Over 90 nests are being monitored. On the island, these warblers start breeding
in early March and nest mainly in shrubs (Lemonade berry, Coyote brush, Monkey
flower), although several nests were found on the ground as well as in trees
(Island scrub oak) at 3 or 4 meters high. A very interesting finding is that
the island sordida warblers are double brooders, in contrast with the mainland
Orange-crowned Warblers that have only one brood a year. Orange-crowned Warblers
feed by gleaning insects from plant leaves. During March the warblers forage
mainly on oaks and in late April and May they also get many insects from the
grass and nectar from flowers.
We are approaching the end of the breeding season for the sordida Orange-crowned
Warblers and the field is loaded with newborn fledglings. So, hurry up, get your
binoculars and try to find them! If you are lucky you will get to see their puffed
orange crown. | 
