Sept. ,1918 EVIDENCE THAT MANY BIRDS REMAIN MATED FOR LIFE 



169 



Among the woodpeckers, one of the best evidences that the same pair re- 

 mains together year after year is the series of nesting cavities excavated up and 

 down a single dead tree or branch. A pair of Cabanis Woodpeckers ( Dryobates 

 V. hyloscopus) had nested for several seasons in the dead top of a tall pine. One 

 winter, this broke off and lodged in the top of an adjoining pine. Even with 

 their nest site in this apparently inseenre position the woodpeckers were unwill- 

 ing to leave it, and their new nest was found dug in the same old tree top in its 

 inverted position. Along the San Pedro River the Cactus Woodpecker (Drtj<>- 

 baies s. cactophilus) is the only one nesting at all commonly. In the lines of wil- 

 lows bordering the irrigation ditches and in the small groups found along the 

 river banks, I had quite a list of pairs whose nests I could count upon finding 

 within certain circumscribed areas. They exhibited individual characteristics. 

 One pair never dug its nest lower than twenty feet from the ground and usually 

 selected a site that overhung the water. Another liked short stubs not over five 

 or six feet tall. Another was partial to fence posts. While these selections were 

 not invariably followed they were so usual that I always began my search by ex- 

 amining -all the available sites of that character before looking at others and was 

 usually successful in my first search. In the giant cactus around Tucson, the 

 Gilded Flicker (Colaptcs chrysoides) and the Gila Woodpecker (Centurus uro- 

 pygialis) were very common and I have a long list of pairs of these two species 

 with specified groups of cactus where they are to be found. 



Of the doves, the Inca Dove {Scardafella inca) and Mexican Ground Dove 

 {Chaemepelia p. pallescens) illustrate my point the best. One pair of Inca 

 Doves in Tombstone nested either in an elderberry tree on a certain corner, or in 

 a mulberry tree some seventy-five yards farther down and across the street. 

 Even repeatedly losing their eggs failed to disturb them. One pair of Mexican 

 Ground Doves always nested in a certain clump of willow brush or an adjacent 

 large willow tree. I believe the other two nesting doves, the White-winged Dove 

 [Melopelia asiatica) and Mourning Dove (Zenaidura m. carolinensis) would of- 

 fer as good examples were it not that the locality where 1 most regularly collected 

 them, along the San Pedro River near Fairbanks, was a favorite hunting ground 

 for the sportsmen of that region and that the pairs were constantly being broken 

 "up by one or the other of the birds being shot. 



The Canyon Towhee (Pipilo f. mesolcucus) and Abert Towhee (Pipilo 

 aberti) could both be relied upon to nest regularly in given spots. A pair of Can- 

 yon Towhees had their first nest of the season always in the vines growing on our 

 house. Their second nest was in a nearby umbrella tree. Their third nest was 

 either in this same tree or in a small Cottonwood just outside the fence. In this 

 case the marked similarity of the eggs each year was very good evidence that the 

 same bird laid them, and as the two birds were resident and hung around the 

 house all the year it seems almost an assured fact that she had the same mate each 

 time. Along the San Pedro River I had a series of pairs of the Abert Towhee 

 located from which I could secure sets whenever I chose, during the season. As 

 many of these birds built in situations where I could collect nothing but the nests 

 (i. e., without the supporting branches) they frequently used exactly the same 

 site year after year. 



I could multiply the illustrations used and make them include the Anthony 

 Green Heron (Butondes v. anthonyi), Western Yellowthroat (Geothlypis t. oc- 

 cidcutalis), Cooper Tanager (Piranga r. cooperi), Western Blue Grosbeak (Gui- 

 raca c. lazida), Arizona Pyrrhuloxia {Pyrrludoxia s. sinuata), Cassin and West- 



