BIRDS OF PENNSYLVANIA, 179 



The nests vary somewhat in size, but the one now before me about 

 the average gives the following dimensions: Height, 6 inches; 

 diameter, 7-J inches ; depth of cavity, 3 inches. Gentry observes that 

 the female begins to deposit her eggs, one ovum per day, the day fol- 

 lowing the completion of the nest. Such may be the case, but my 

 observation has been that oviposition often does not take place until 

 three or even five days subsequent to the completion of the nest. The 

 complement of eggs is commonly spoken of as six ; generally, how- 

 ever, I have found five, and regard this number as the full quota. 

 The eggs are light greenish (sometimes pale rusty brown), spotted, 

 blotched and lined with black and dark brown; they measure about 

 1^ inches long and .90 of an inch wide. The period of incubation is 

 from fourteen to fifteen days. The parent birds evince marked solici- 

 tude for their nest and its contents. 



It is evident from the writings of various authorities that the nest- 

 ing sites of this species vary considerably. By Nuttall and others we 

 are informed that they sometimes build in bushes. From the works 

 of Audubon it is learned that in the South they build chiefly in hollow 

 trees. 



Wilson, in speaking of the Crow Blackbird, says : u A singular 

 attachment frequently takes place between this bird and the Fish 

 Hawk. The nest of the latter is of very large dimensions, often three 

 or four feet in breadth and from four to five feet high, composed, ex- 

 ternally, of large sticks or faggots, among the interstices of which, 

 sometimes, three or four pairs of Crow Blackbirds will construct their 

 nests while the Hawk is sitting or hatching above. Here each pur- 

 sues the duties of incubation and of rearing their young, living in the 

 greatest harmony and mutually watching and protecting each others' 

 property from depredators." 



I have found these birds building in common house ivy (Hedera 

 helix) but never in bushes, and only on two occasions have I discov- 

 ered their nests in hollow trees ; both of these nests were built in ap- 

 ple trees. One was constructed in a limb about seven feet from the 

 ground, the other was placed about twenty feet from the earth, neither 

 of these differed materially in their make up from the average nest. 



FOOD. 



To our agriculturists this is a subject worthy of some consideration. 

 It appears to be the prevailing opinion among many farmers the 

 majority, in fact that Crow Blackbirds are in many ways detrimental, 

 and in no particular are they beneficial. This belief, evidently handed 

 down from one generation to another, is taken in its full meaning, 

 widely at variance with positive fact. Among the first of our vernal 

 migrants come the Crow Blackbirds in large flocks which disperse 



