28 U.S. NATIONAL MUSEUM BULLETIN 23 3 



show interest in a host nest at a stage considerably later than the 

 time of egg-hiying. However, as Forbush correctly stated, it is not 

 clear that this was a case of prolonged duration of such an interest. 



The other case, also cited by Forbush, an observation by L. B, 

 Fletcher (1925, pp. 22-24), had to do with a fledged cowbird already 

 out of the nest. Fletcher trapped an adult female cowbird with a 

 recently fledged young one, saw the former feed the latter, banded 

 both birds, and released them. Later he saw the two together, the 

 hen still feeding the young one. She fed only the banded fledgling 

 and no others although there were other young cowbhds present. As 

 Forbush correctly said, this is a reliable observation but affords no 

 evidence to prove actual mother-and-child relationship. Such may 

 be inferred, but not more than this, as many birds occasionally feed 

 young other than theh own. "It shows, however, that the adult 

 cared for one particular j^oung, which may have been her own." 



Although of questionable pertinence here, an observation by Wiest 

 near Butler, Pennsylvania, recently published by Preston (1961) in 

 a local newspaper, should be mentioned. Wiest found a chipping 

 sparrow's nest containmg two eggs of its own and two cowbird eggs; 

 he showed it to Preston, who removed the latter eggs. This was on 

 May 18. The sparrows deserted the nest soon afterward. On 

 May 30 Wiest saw a female cowbird visit the nest. She flew to it, 

 fluttered her wings, flew down to the ground and again up to the 

 nest in what seemed to the observer to be a state of excitement. 

 Then she left but soon returned with four other cowbirds, two males 

 and two females. (Wiest assumed that the original female was one 

 of this party.) The five cowbirds tore the nest apart, eventually 

 knocking it to the ground, and then flew off. In his report of this 

 incident Preston felt it noteworthy that the time between the first 

 observation on May 18 and the second on May 30 was ''just about 

 the time needed to hatch cowbird eggs, and if we surmise that the 

 fluttering female was the mother of the eggs, or of one of them, then 

 it looks as if she had come back to see if her offspring had hatched. 

 Finding neither young cowbirds nor cowbird eggs, she seems to have 

 called in her friends to destroy the nest of the negligent foster-parent. 

 It is easy to read human motivation into bird behavior, and this is 

 regarded as a deadly sin by ornithologists, but it is hard to avoid 

 the conclusion that the fluttering female was the mother of at least 

 one of those eggs, continued to be interested in it, and was greatly 

 upset by what she found out." 



It is obviously impossible to judge this case because there is no 

 certainty that the "fluttering female" was the parent of one or both 

 of the eggs or that she was even present in the aggressive action of 

 the flock of five cowbirds. It should be mentioned that this destruc- 



