32 Goss on Breeding of the Duck Hawk. 



theory of evolution by means of what has been termed "natural 

 selection " and " sexual selection " have been betrayed. 



In conclusion, I desire to call attention to an interesting coinci- 

 dence between the manner of nesting among birds and the color of 

 the eggs, and one so striking that it is almost surprising that some 

 ingenious theorist has not seized upon it as a basis for a " theory of 

 birds' nests," either independently or as a modification of that pro- 

 posed by Mr. Wallace. It curiously happens that nearly all birds 

 that nest in holes, either in the ground or in trees, lay ivhite eggs, 

 embracing, for instance, all the Woodpeckers, Kingfishers, Bee-eat- 

 ers, Rollers, Horubills, Barbets, Puff-Birds, Trogons, Toucans, Par- 

 rots, Paroquets, and Swifts, while only occasionally are the eggs 

 white in species which build an open nest. In only two or three 

 groups of land bii'ds, co-ordinate with those just named, that build 

 an open nest, are the eggs white, namely, the Owls, Humming-Birds, 

 and Pigeons. On the other hand, in only two or three small groups 

 of species that nidificate in holes are the eggs speckled or in any 

 way colored. There is, in fact, a closer relationship, or rather a 

 more uniform correlation, between the color of the eggs and the 

 manner of nesting than between the color of the female parent and 

 the concealment or exposure of the nest. There are, however, here 

 apparently too many exceptions to bring this coincidence into the 

 relation of cause and effect. It is perhaps rather comparable with 

 the pattern of coloration that so often, to a greater or less degree, 

 marks nearly all the species of a whole natural family, and often 

 prevails throughout large genera, for which the conditions of envi- 

 ronment offer no explanation, since it as often occurs in cosmopoli- 

 tan groups as in those of local distribution, and which, in the pres- 

 ent state of our knowledge, seems wholly inexplicable. 



BREEDING OF THE DUCK HAWK IN TREES. 



BY N. S. GOSS. 



As the Falco communis var. anatum is supposed to nest almost 

 exclusively on high rocky cliffs, and rarely if ever in other situa- 

 tions, I think it will be of interest for me to say that I found 

 in February, 1875, a pair nesting about three miles southeast of 

 Neosho Falls, Kansas, in the timber on the banks of the Neosho 



