480 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



Cliff swallows, which nest in situations well above level ground, 

 would not be expected to be molested by snakes, but nevertheless 

 cases on record indicate that snakes may sometimes prove to be a 

 menace to nesting birds. Sawyer (1907) reports that an adder was 

 discovered under the eaves of a barn where it was observed to be 

 busily engaged in devouring cliff swallow eggs, and Cameron (1908) 

 writes that a rattlesnake climbed the veranda poles of the Cross S 

 ranch on Mispah Creek and devoured all the nestlings in reach. 



Ants have proved very destructive to cliff swallows and other 

 forms of life at San Diego, Calif. According to Anthony (1923) a 

 colony of cliff swallows that had nested in one of the towers at the 

 San Diego Museum was destroyed by the so-called Argentine ant 

 introduced presumably from South America. Twenty-five dead 

 nestlings were found in the deserted nests examined. The young 

 were covered with the ants, while a steady column of the insects 

 marched from the top of the tower to the ground. 



The cliff swallows are more or less infested with Mallophaga and 

 other external parasites, but so far as I know no comprehensive 

 study has been made of the parasites and diseases of the cliff swal- 

 low. Knight (1908) states the nests often contain bird lice, ticks, 

 and bed bugs. Several observers have reported finding bed bugs in 

 the nests of cliff swallows. Cameron (1908) states that in Montana 

 the ranch owners destroy cliff swallows because their presence brings 

 bed bugs into the houses. Thus indirectly through man bed bugs 

 become destructive to the best interests of the cliff swallow. Accord- 

 ing to some observers the prejudice against the cliff swallow in cer- 

 tain sections of the Middle West is so great that these birds may have 

 to return to their primitive nesting sites on cliff's if they are to be 

 perpetuated. Such an attitude toward a very beneficial species of 

 bird is unfortunate and unwarranted. (See Widmann, 1907, p. 201.) 



Predaceous birds cannot be considered as serious enemies of the 

 cliff swallow. Indeed there are instances where the cliff swallows 

 have nested in apparent harmony with prairie falcons and duck 

 hawks. The appearance of a hawk in the vicinity of a colony of 

 cliff swallows never creates any evidence of excitement, whereas 

 other passerine birds may exhibit great concern. 



Unseasonable weather, especially sudden drops in temperature after 

 the swallows have arrived in spring, have sometimes proved destruc- 

 tive. Audubon (1831), writing concerning cliff swallows observed 

 at Henderson on the Ohio River in the spring of 1815 states : "It was 

 an excessively cold morning, and nearly all were killed by the severity 

 of the weather." Kimball (1889) made an investigation of the mor- 

 tality of cliff swallows in June 1889 at Rockford, 111., after it was 



