Reproduction 109 
5. In the case noted the Lark eggs (or at least egg) was laid 
before the Cowbird, apparently, and incubation may have begun 
then. 
6. The food, in June at least, is favorable, however. At 
Ithaca I placed a newly hatched Cowbird in a nest with Lark 
eggs. The Cowbird prospered and when removed ten days later 
was well developed and weighed 21.7 grams, about the weight 
of a Lark at that age. However, young Larks would have gone 
from the nest at this age but the Cowbird was not yet ready to 
do so. 
Grane and 
contineters 
z= 
I} 
= growth in total length 
i 
growth in lengta 
minus tail 
6 
Figure 17 
tn = 3 oe ae Bae’ ee 10 <« & 36 
Fig. 17. Average growth in hen and length of a varying number 
of Prairie Horned Lark y 
7. The Horned Lark has no aversion to foreign eggs for a 
Song Sparrow egg, placed with Lark eggs, was not disturbed. 
Here, then, seems to be a possible host that for reasons not 
quite clear the Cowbird almost wholly overlooks. 
Protection for the young.—As birds of the open, and on 
the ground, the young of the Larks have need for two important 
features to protect them: silence, and the proper coloration. 
These two characteristics they possess in remarkable degree. At 
