160 BULLETIN 19 6, UNITED STATES NATIONAL MUSEUM 



Few birds are more valiant in resisting attacks on their brood and 

 capable of creating a greater hubbub over the presence of marauders. 

 Such an occasion invariably attracts other birds of the vicinity, 

 adding a veritable chorus of protests. The parent birds, very tense, 

 with crests erect, swoop and dash fearlessly, ' sometimes venturing 

 so close that their wings strike the intruder. More often than not 

 they are successful in driving the enemy to cover. 



As is true with many birds, the hermit thrush is subject to infesta- 

 tion by a number of external parasites. Under ordinary conditions 

 none of them prove fatal to the bird, but some of them may be very 

 annoying to the host when they become abundant. Harold S. Peters 

 (1936) has reported three species of lice, Degeeriella eustigma (Kellogg), 

 Myrsidea incerta (Kellogg) , and Philopterus subflavescens (Geoffroy) ; 

 two species of bird flies, Ornithoica conjluenta Say and Ornithomyia 

 anchineuria Speiser; two ticks, Amblyomma tuberculatum Marx and 

 Haemaphysalis leporis-palustris Packard; and the mite Trombicula 

 whartoni Ewing. In addition to the above Peters (1933) also reported 

 the tick Ixodes brunneus Koch as a parasite of the hermit thrush. 



According to Herbert Friedmann (1929) the hermit thrush is a very 

 uncommon victim of the cowbird, and at the time of writing he knew of 

 only six definite records. Contrary to Friedmann's statement, I have 

 found it to be a frequent victim. I have seen fewer than 15 nests of 

 the hermit thrush, yet four of these were parasitized by the cowbird. 

 On May 31, 1920, I found a nest near > Brunswick, Maine, that 

 contained three eggs of the hermit thrush and two eggs of the cowbird. 

 This nest was destroyed by some predator a few days later. On July 

 8, 1928, a nest containing three eggs of the hermit thrush and one egg 

 of the cowbird was found at Douglas Lake, northern Michigan. In 

 this nest the cowbird hatched first and continued to thrive until it left 

 the nest. Two of the eggs of the hermit thrush hatched, the third was 

 sterile. Both of the two hermits were also successfully reared. On 

 July 6, 1928, also at Douglas Lake, Mich., I found a nest containing 

 two eggs of the hermit thrush and one egg of the cowbird. On^July 12 

 the cowbird egg hatched, followed a day later by the hatching of one 

 of the thrush eggs; the other thrush egg was sterile. The thrush and 

 cowbird competed for food, but the cowbird proved more aggressive 

 and maintained its lead in size throughout the nesting period. On 

 July 19, when the cowbird was seven days old and the hermit six days 

 old, there was a marked difference in weight and size and relative de- 

 velopment of the feathers. By July 25 both the cowbird and thrush 

 had left the nest. The adult hermit was seen feeding the cowbird 

 nearby, but the young hermit was not seen, although I have no reason 

 to believe that it perished. 



A fourth nest of the hermit thrush parasitized by the cowbird was 



