Mar., 1907 MIGRATION AND NESTING OF THE SAGE THRASHER 



43 



I should like to hear of observations from the Cajon Pass and points in the vicinity 

 of Antelope Valley. 



With this intere.st in the thrasher during migration it was with much pleasure 

 I looked forward to studying him during the season of family cares; and when 

 spring opened in southwestern Colorado I began sharpening eyes and pencil. But 

 no thrashers appeared and I had about given up hope of seeing him in his summer 

 home when a wagon trip thru part of Montezuma County down into the Southern 

 Ute Indian Reservation gave me opportunity for a few observations. My time was 

 limited and only superficial work could be done. I saw the first birds in the sage 

 brush near Cortez, the county seat of Montezuma County, altitude near 6000 feet. 

 They were rather tame, flying from brush along the roadside up onto fence posts. 

 Two or three old nests were seen but the birds were not numerous. 



From Cortez southward was a constant tho gradual descent toward the San 

 Juan River. As the altitude decreased the number of thrashers increased and more 

 old nests were seen. I had no time, while en route, for search, but during the 

 noon hour I "took to the brush" and found the first new nest. It was in a thick 

 sage bush {Artemisia trideutata) and was discovered by flushing the birds from an 

 adjoining bush. The nest contained the shells of two freshly broken eggs, the 

 cause of breakage not being apparent and the nest not otherwise disturbed. This 

 was on May 31. lyater in the day I saw two families of young birds that had just 

 left the nest, one brood of nestlings not being able to fly sufficiently to escape capture 

 and inspection. The di.scovery of these birds so nearly matured left me small hope 

 of finding any eggs. 



That afternoon I reached Navajo Springs, the Southern Ute Agency. The 

 agency is near the New Mexico line and is located in a narrow pass between Ute 

 Peak and a line of bluffs capped with the characteristic rim-rock of this country. A 

 cut or arroyo begins a mile above the agency and extends down the pass, deepen- 

 ing all the while. £^ small stream of water was flowing along the bottom for po.ssi- 

 bly two miles before sinking. On each side of the cut was a strip of bushy or 

 shrubby growth composed of sage brush, grease- wood (Sarcohatiis vcnniculatus.) , 

 and another desert shrub not familiar to me. Uocally it is called "chico-brush" and 

 is a good indication of alkali in the soil. 



In this growth were many thrashers, some few lark buntings and several 

 mocking-birds. Taking advantage of what little daylight remained, after putting 

 up my team I made a hasty search in the immediate vicinity of the agency and 

 found two nests with eggs. The first was in a sage two and one-half feet from the 

 ground and contained seven beautiful greenish-blue eggs specked with rich brown. 

 This nest was made of dry twigs from sage and grease-wood, and was lined with 

 sage bark, horse hair, goat hair, and rabbit fur. The second nest was also in a sage 

 bush and about two feet from the ground. It was similar in construction to the 

 first but the lining contained no rabbit fur and the set was of six eggs. Both sets 

 were about one-third incubated. 



June 1, I was again afield for a short time and found two more nests. One 

 was in a grease-wood two and one-half feet from the ground and contained six eggs 

 about as much incubated as those found the day before. This nest was similar to 

 the others except for a distinct arch or platform of dry twigs just above it. The 

 arch looked more like design than accident but I formed no decided opinion in regard 

 to it. The fourth nest was in a sage two feet from the ground and contained three 

 fresh eggs. In addition to these thrashers' nests I found a lark buntings' nest 

 with five fresh eggs, and a mocking-birds' with five parth' incubated eggs; also 

 some young chipping sparrows. 



