26 CuURMP.. L/'s/ of Birds of S(7n yos('. Costa Rtca. rjanuary 



white; after the contents were removed thev had a very pale bhiish shade. 

 The eggs of the Cowbird are larger and much darker, varying between 

 pale blue and pea-green. Incubation in the eggs oi B. gutturalis was far 

 advanced, one of the eggs being broken in removing *he contents. The 

 two remaining eggs measure .67X.90 and .64X.88 inch. The Cowbird 

 eggs were perfectly fresh ; they measured .75 X .94 and .75 X .86. The larger 

 is ovate in form, and the sinaller rounded ovate. The nest was placed in 

 an upright fork of a small coffee tree, about seven feet from the ground, 

 and was not well concealed. Outwardly it is constructed of coarse, dry 

 grass stems, and it is lined with a little soft, fine, dry grass. It measures : 

 outside diameter 4.75, depth 2.50 inches; inside diameter 2.50, depth 1.75 

 inches. I almost placed my hand on the female before she left the nest. 

 She made no fuss, flying quietly into the low bushes near by and disap- 

 pearing. 



A second nest was toWen June 2, 1889, containing five eggs, three of the 

 Cowbird. The eggs of B. gutturalis were fresh ; one of the Cowbird eggs 

 was much incubated, the other two fresh. The B. gutturalis eggs meas- 

 ure .90X .65 and .91X.65; one is marked with a few small specks of chest- 

 nut. The nest measures 2.75 inches in inside diameter by 1.75 in depth; 

 outside diameter, 7.00X5.00, depth 4.00 inches. It is rather large and 

 bulky and was built in the tops of some bushes where it was not well 

 supported. The outside consists of rough dry grass stems; within this 

 are smaller plant fibres and grass blades and a lining of very fine, dry grass 

 and horse-hairs. 



A third nest, taken June 11, 18S9, contained three fresh eggs. The nest 

 was rather peculiarly situated, being placed about four feet fiom the 

 ground, against the tiunk of u large tree, in the hollow formed by the 

 branching of a parasitic plant that clung to the bark, and was most excel- 

 lently concealed by leaves, and by far the neatest and most compact nest 

 of the species I have seen. The three eggs measure .67X.91, .65X.89, and 

 .66X.90 inch. A week before, in the bushes only a few feet from this 

 nest, I took an abandoned nest containing one Cowbird's egg. 



I took the last nest in 1S89 on June 20. It contained two eggs of B. gut- ■ 

 turalis and one of the Cowbird; all were fresh. The eggs oi B. gutturalis, 

 as usual, were white before being blown, and a very pale bluish after the 

 contents had been removed. The eggs are ovate, measuring .95X.68 and 

 .96X.68 inch. The Cowbird's egg measures .93X.73 inch, and in shape is 

 a short ovate. The nest is roughlj' constructed, the materials used being 

 much coarser than usual. Measurements: outside diameters 5.50X6.00, 

 depth 2.75 inches; inside diameter 2.38, depth 1.50 inches. The bird was 

 not once seen nor heard. June 22 I shot a female with a half-formed egg 

 in the oviduct. After this date all the specimens I secured indicated, by 

 the ovaries, that the nesting season was passed. At this same time the 

 birds became very shy, usually keeping themselves hidden in the low, 

 tangled hedges. 



Young birds have a slightlv olive shading on the back. The white 

 crown stripe is only indicated by a few grayish white feathers. The throat 



