70 BULLETIN 621 U. S. DEPARTMENT OF AGRICULTURE. 



ous Rhus seeds (poison ivy and poison sumac) for each pellet. Along 

 with these were seeds of nonpoisonous sumac, grapes, dogwood, 

 hackberry, wild bean (Strophostyles) , and buckthorn (Bumelia). A 

 mass of material gathered at a roost near Baltimore contained 156 

 seeds of poisonous Rhus, estimated to be 25 per cent of the bulk of 

 the pellets. These also contained 11 seeds of nonpoisonous sumac, 6 

 of greenbrier, 4 of juniper, and 1 of hackberry. W. L. McAtee, of 

 the Biological Survey, has informed the writer that at the roost 

 formerly located at Woodridge, near Langdon, D. C, he recorded the 

 following species of plants in such abundance as to justify the belief 

 that they had sprouted from seeds brought there by crows: Poison 

 ivy, poison sumac, flowering dogwood, sour gum, arrowwood, and 

 frost grape. He also stated that in 1 square yard there were 51 plants 

 of poison ivy. 



The seeds deposited at winter roosts form only a portion of the 

 material of this character cast up by these birds (PI. II, fig. 2). 

 These pellets are dropped here and there over the birds' daily feed- 

 ing range, and under such circumstances probably a much greater 

 proportion of the seeds sprout. Conditions in the average roost are 

 not advantageous to the germination of a large part of the deposited 

 seeds, especially in the dense pine woods so frequently chosen. 



When the seeds thus distributed are of valuable trees and shrubs 

 or even of harmless plants, the crow no doubt is performing a distinct 

 service, but the dispersal of seeds of poison ivy and poison sumac 

 must be considered undesirable. Examination of 1,340 stomachs of 

 adult crows showed that seeds of these poisonous weeds constitute 

 1.49 per cent of the yearly food. Most of them are eaten during fall 

 and winter, January being the month of greatest consumption (5.02 

 per cent). When it is remembered that practically all these seeds 

 would develop into weeds of the most noxious character should they 

 be deposited in a favorable environment, it is not surprising that the 

 crow has been the subject of considerable criticism on this score. 



While it must be admitted that no agency aiding in the reproduc- 

 tion of poisonous plants should receive encouragement, it will be well 

 before being unduly severe on the crow to notice other factors work- 

 ing toward the same end. Records of birds' stomachs examined by 

 the Biological Survey show that no less than 65 species of birds feed 

 on the seeds of poisonous Rhus. Many of these birds possess the 

 same objectionable habit of regurgitating the seeds, and in several 

 cases the percentage of such food eaten exceeds that of the crow; 

 but none of them leaves so large a part of the seeds of poison ivy 

 and poison oak in places where they will never germinate as does the 

 crow. The latter, then, is in a way conferring a benefit in feeding 

 on these seeds, as by so doing it reduces the supply which otherwise 



