COMMON ROCK WREN 291 



condition, and upon examination was found to be infested with large 

 white grubs several of which had buried themselves deep into the bird's 

 head and were gradually sapping its vitality. These grubs were nearly 

 one half inch in length and were all buried out of sight under the skin." 

 Dr. Walter P. Taylor (1912) observed one "attacking a chipmunk 

 which was sitting on a rock, swooping at it in the same way that a 

 mockingbird assaults a cat," which suggests that small mammals may 

 take their toll of eggs or young. And Dr. Friedmann (1934) men- 

 tions several cases where rock wrens have been imposed upon by 

 cowbirds. 



Winter. — Rock wrens retire to some extent in autumn from their 

 summer haunts at the higher altitudes in the mountains as these become 

 covered with snow, though they seem reluctant to leave as long as por- 

 tions of their range remain open. Many remain in their rocky re- 

 treats all winter, but some others seek their winter food in more shel- 

 tered brush lands or on open mesas. The rock wren has not yet 

 become a dooryard bird, but it sometimes appears in the neighbor- 

 hood of houses and gardens. A. H. Anderson (1934a), writes of such 

 a case: 



Here on the outskirts of Tucson, Ariz., it lias been present for the last two 

 winters around my home. The area is of typical creosote-bush mesa, shading 

 gradually into the mesquite and catclaw border of Rillito Creek close by. Some 

 of the land is occupied by 1-acre, suburban farm and chicken-ranch tracts. 



A single Wren seems to have occupied the territory during both winters, though 

 several times two and three birds were seen. None was seen during the summer 

 of 1933. Usually this individual accompanied the mixed flock of birds that 

 frequented the district, Gambel's and Brewer's Sparrows, Cactus Wrens, Palmer's 

 Thrashers, and House Finches. 



Its curiosity was very pronounced and one could easily regard the bird as tame. 

 Sometimes I could approach as close as 5 feet as it stood bobbing upon a wood-pile, 

 fence-post, or chicken-house. Several times it came through the open house-door, 

 and occasionally it would climb around on the window-sill. It inspected every- 

 thing in the vicinity — houses, automobiles, chicken-houses, and wells. 



DISTRIBUTION 



Range. — Southwestern Canada to Costa Rica. 



Breeding range. — The rock wren breeds north to southern British 

 Columbia (Cache Creek, Kamloops, and Shuswap) ; southern Alberta 

 (Jasper House, possibly, and Red Deer) ; southeastern Saskatchewan 

 (Cypress Hills, Eastend, and Wood Mountain) ; and North Dakota 

 (Williston and Charlson). East to western North Dakota (Charlson 

 and Mandan) ; western South Dakota (Pierre, Rosebud, and casually 

 to Yankton County) ; central Nebraska (Valentine and Calloway) ; 

 central Kansas (Rooks Creek and Ellis) ; western Oklahoma (Gates) ; 

 central Texas (Vernon, Putnam, Kerrville, and San Antonio) ; 

 through Mexico (Tamaulipas, Veracruz, and Chiapas) ; western 



