NO. 9 BIRDS OF ISLA COIBA, PANAM A—WETMORE 79 
tropical lowlands, since elsewhere in Panama the species inhabits the 
mountain areas in the high tropical or subtropical zone, though there 
are exceptions, as for example at San Félix in eastern Chiriqui, where 
I found them at an elevation of a little over 100 meters. 
On Coiba, as elsewhere, these robins came to feed in berry-bearing 
trees, and at such times might range much higher above the ground 
than is their normal custom. Occasionally I noted them searching 
for food among dry, fallen leaves on the forest floor. Often I heard 
their complaining notes from the undergrowth, a low whining 
pree-ee-er or a slightly harsher chur-r-r. In the latter part of January 
they began to sing, the song suggesting that of the mainland clay- 
colored robin (Turdus grayi casius), but with notes higher and de- 
livery slower. 
As Dr. Eisenmann remarked in his original description, this race, 
peculiar to Coiba, is most similar in color and size to Turdus a. 
daguae, found from the highlands of eastern Darién through western 
Colombia to northwestern Ecuador. T. a. coibensis is larger, more 
olive above and grayer below, with the unmarked white area on the 
foreneck less in extent. The Coiba form is completely different from 
T. a. cnephosus of western Panama, which is its near neighbor geo- 
graphically, that bird being decidedly grayer above and on the sides, 
whiter on the abdomen, and decidedly larger. In life the bare edge 
of the eyelid in coibensis is dull yellow, as it is in the mainland race. 
Since coibensis was described from only two specimens it is useful 
to give measurements from the series that I collected: 
Males (8 specimens), wing 107.5-117.5 (111.7), tail 76.8-89.1 
(84.0), culmen from base 20.5-22.9 (21.6), tarsus 29.7-31.8 (30.4) 
mm. Females (6 specimens), 108.0-113.4 (112.1), tail 79.5-86.8 
(82.6), culmen from base 21.0-23.3 (22.2), tarsus 29.0-31.0 (30.3) 
mm. 
As material of these white-throated robins has accumulated in 
museums, supposed distinct species have been found to merge, until 
now it is evident that there is no clear-cut line on which to divide 
them in the vast area between México and northern Argentina, 
though variation geographically is extensive. All are to be included 
under the specific name Turdus albicollis. 
Family SytviipAE: Old World Warblers, Gnatcatchers 
POLIOPTILA PLUMBEA (Gmelin): Tropical Gnatcatcher, Cazajején 
Todus plumbeus GMELIN, Systema naturae, vol. 1, pt. 1, 1788, p. 444. (Surinam.) 
This was another common species found in leafy cover that ranged 
indifferently from low second-growth thickets near the shore to the 
