CATBIRD 325 



Incubation. — Mrs. Helen G. Wliittle (1923) studied a pair of cat- 

 birds that built near her home in Peterboro, N. H. She writes : 



The male took no share in incubating, nor did he ever, I think, make any 

 attempt to brood the young. If he came to the nest and found the female 

 absent, during incubation, he would fidget on a nearby twig in a helpless, wor- 

 ried fashion, but apparently never thought of taking her place. * * * Dur- 

 ing incubation, the male sang very infrequently within my hearing, and brought 

 food to the female so seldom that I wondered how she could survive. There 

 was however, evidence that the male of this pair was an inexperienced bird, 

 possibly young, and this his first family. 



The female, left to do all the incubating, was very faithful to her task and 

 sat patiently day after day through an extremely rainy period, which con- 

 tinued with only brief respites, all through June and early July in southern 

 New Hampshire. One afternoon there was a severe hailstorm, and the female 

 on the nest with feathers drawn close, bill pointing straight up and eyes shut, 

 made as good a watershed of herself as possible, while hailstones the size 

 of large peas pelted her unmercifully. 



The incubation period of the catbird as reported by various observers 

 is 12 or 13 days. 



Young. — Ira N. Gabrielson (1913) describes the details of the 

 hatching of the eggs in two catbirds' nests as follows, the observations 

 being made by Arthur F. Smith : 



At 4 : 55 a. m. one more egg was pipped, evidently by the old bird, as it was 

 chipped inward and directly around the center of the egg. The egg hatched at 

 5 : 55 p. m., the young bird forcing the shell open by rolling and plunging gently 

 and by some use of the feet and wings. At 6 : 45 the female carried away half of 

 the shell and returned at 6 : 48 with something in the bill which she swallowed, 

 tho I could not determine whether it was the crushed shell or food. She left the 

 nest at 6 : 53 only to return at 6 : 55 and take away the remaining shell. 



In nest C the first egg was pipped at 9 : 00 a. m. on July 20 and at 7 : 00 p. m. 

 all three were pipped in practically the same place. The first break in each 

 shell came from within and was a little beyond the center of the egg toward the 

 larger end. It was simply a slight bulging evidently produced by a blow from 

 the beak of the young bird. A series of cracks radiated in all directions from 

 tiis place. The next thing noticed was the extension of a series of these bulges 

 around the egg at right angles to the long axis. At 11 : 30 a. m. July 21 one egg 

 had hatched and the shell had been removed. The two other eggs had four of 

 these breaks extending half way around the shell. From this time until 3 o'clock 

 there was no change in appearance altho a number of times the female picked 

 gently at the cracked places. On these occasions I could not see that she took 

 anything away although she undoubtedly broke the shell a little by these actions. 

 At 3 : 00 p. m. she left the nest and was hardly out of sight when the egg she 

 had been picking began to hatch. A dark line appeared around the shell and 

 enlarged in a series of tiny jerks until I could see the young bird kicking and 

 twisting within. The crack grew steadily wider until it was fully half an inch 

 wide on the top of the egg, tho it had hardly opened at all on the side next the 

 nest. At this point the female returned and immediately commenced picking at 

 the shell membrane which still held the two pieces of shell together. As it came 

 away a bit at a time, she swallowed it, repeating the process until the two pieces 

 had fallen apart. She then seized the smaller piece (the big end of the egg and 

 the one that had contained the head of the nestling) and carried it away, leaving 

 758066—48 22 



