THE CROW AND ITS RELATION TO MAN. 71 
would be available for more potent seed distributors. Nor in ex- 
tending its range is poison ivy dependent entirely upon the trans- 
portation afforded by bird life. It readily reproduces itself through 
its roots and ofttimes spreads over considerable areas in spite of 
vigorous efforts to exterminate it. It is apparent, then, that even 
the total extermination of the crow would have little effect upon 
the growth of poisonous Rhus, inasmuch as there are many other 
agencies effecting the same results. The problem is one similar to 
that of the dissemination of live-stock diseases, the control of which 
some persons maintain can be effected by the elimination of crows 
and turkey buzzards, overlooking the fact that there are numerous 
other agencies engaged in the work of dispersal, and that the removal 
of only one or two would result in no appreciable relief. 
NATURAL ENEMIES. 
Aside from man the crow appears to have few natural enemies. 
His unusual wariness stands him in good stead in avoiding many of 
those mammals and birds which prey to a considerable extent upon 
bird life. The great horned owl alone seems to be inclined to feed on 
the crow as a more or less regular item of diet. Ample opportunity 
is afforded this species to secure such food at crow roosts, which it 
appears to frequent regularly for this purpose. 
In this connection, E. H. Forbush, of Massachusetts, has said i 1 
After the first fresh snowfall, I visited an extensive roost, finding the feathers 
and a few other remains of a freshly killed crow. At the spot where the crow 
was borne to the ground were the strong imprints of the characteristic tips 
of the wings of the great horned owl. These owls habitually take crows from 
their roosts or nests at night. 
The antipathy between crows and owls as a class is frequently 
manifested in the " mobbing " of one of the latter by a large number 
of crows. Recognizing the comparative helplessness of these noc- 
turnal birds of prey when subjected to bright daylight, the black 
fellows appear to take great delight in molesting them when they 
are found abroad during these hours. 
G. B. Wellman, of Maiden, Mass., reports: 
The chief thing that our crows in the fells seem to busy themselves with in 
the winter months is harassing the owls. They have in consequence driven 
nearly all the barred and screech owls from the park. There has been, I am 
sure, an added nuisance made here by the increase of the noxious rodents 
since the owls left. 
Occasionally the red-tailed and red-shouldered hawks will turn 
upon their tormentors. Examination of stomachs by Dr. Fisher 
revealed six records of this work on the part of the former and one 
by the latter bird. 
1 Forbush, E. H., Two Years with the Birds on a Farm, p. 39, 1908. 
