328 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



of the six nestings were the same individuals, but presumably they 

 were. These three cases indicate a constancy of catbirds to their terri- 

 tory and to their mates. 



Geoffrey Gill ( 1935, 1936a) obtained somewhat different results with 

 catbirds banded at Huntington, Long Island. In 12 cases he studied 

 not a pair remained mated for two broods in a single season. Con- 

 siderable variation was exhibited by the birds in their return to the 

 same territory. One male was constant to one territory for four con- 

 secutive summers and six nestings. This male had six different mates 

 in 5 years, but in the last 2 years, as he grew older, he had only one 

 nest each season and during this period was faithful to the same mate. 

 The catbirds that Mr, Gill studied frequently changed their territory 

 for different nestings. It is evident that there is considerable indi- 

 vidual variation in the constancy of catbirds to their mates and 

 territory. 



An anonymous writer (1887) reports from Laramie, Wyo., that he 

 found a catbird living on intimate terms with a shrike ; both pairs of 

 birds built their nests in the same bush, but each seemed to hold un- 

 disputed possession of their particular side of the bush. Mrs. Ken- 

 neth B. Wetherbee (1930) reports a unique case of the interrelation- 

 ship of a pair of catbirds and a pair of robins, which built their nests 

 in the same clump of lilacs. The robin and catbird took turns in incu- 

 bating the catbird eggs, and when the young hatched they were 

 brooded by both robins and catbirds. The robin's nest was a few 

 feet above that of the catbird and was not discovered until the young 

 catbirds had left their nest. It would be interesting to know whether 

 the catbirds assisted the robins in their household duties. 



Catbirds have been known to care for the young of other birds. 

 Earl Brooks (1922) writes of a brood of orphaned cardinals that were 

 fed and mothered by a catbird, and W. J. Hay ward (1937) reports 

 a case where a mother catbird fed a half-grown flicker that had been 

 dislodged from its nest and separted from its parents during a severe 

 storm. The feeding instincts are strongly developed in catbirds, and 

 if they have lost their own young through some misfortune they will 

 readily adopt the offspring of others. 



In contrast to the behavior described above the catbird occasionally 

 destroys the eggs of other birds, but this habit is not characteristic of 

 the species. J. B. W. (1884) reports he saw a catbird destroy an egg 

 of the wood pewee before the latter succeeded in driving it away from 

 its nest. Edwin Dixon (1930) states that a catbird was found robbing 

 a chipping sparrow's nest. It ate the contents of one egg and picked 

 holes in the other two. Proof that the egg was eaten was obtained by 

 shooting the catbird. Leda W. Chace (1931) saw a catbird glide into 

 a locust tree outside her window where a robin's nest was located. The 

 catbird was seen to thrust its bill into one of the eggs and lift it clear 



