ARIZONA PYRRHULOXIA 27 



likewise behind the cardinal in the Rillito drainage valley. However, 

 along the Santa Cruz River the pyrrhuloxia leads in almost every 

 winter census. In 1947 there were 53 pyrrhuloxias and 25 cardinals 

 recorded. No summer counts are available. 



Why the pyrrhuloxia has not established itself in the irrigated farm- 

 lands along the Gila River westward to the Colorado River is not 

 known. Certainly it cannot be because of the higher temperatures 

 of the lower elevations, because the species occurs in Sonora, Mexico, at 

 probable equally high temperatiu"es and also at sea level. 



Mr. Bent found a few pau's of the Arizona bird in the mesquite 

 brush along the San Pedro River near Fairbanks, and found it com- 

 mon in the mesquite forest along the Santa Cruz River, south of 

 Tucson. In the Santa Rita Mountains, Mrs. Bailey (1923) reported 

 it as found "in Madera Canyon at 4,900 feet, where there was a patch 

 of Lower Sonoran mesquite" and in stony gulches "bordered by mes- 

 quite." It might well be called the mesquite cardinal, since it seems 

 fond of this association, but it is also seen at times in trees about 

 houses. 



Territory. — Some years before the intensive studies of territorial 

 behavior of birds began, Willard (1918) expressed the belief that pyr- 

 rhuloxias remain mated for life. He had found them nesting year 

 after year in the same locations. Very probably it was the location 

 and not necessarily the pair that was constant. We know today that 

 good territories are usually occupied regularly. Whatever the status 

 of the birds' bond, the pairing must begin very early in the spring, 

 even when groups of individuals are in evidence. By the middle of 

 February singing can be heard. Although the extent of territorial 

 boundaries is not known, Brandt (1951) gave us a hint of the presence 

 of territorial boundaries when he reported finding a pair of pyrrhu- 

 loxias "about every hundred yards" near the San Pedro River. 



Gould (1961) studied the behavior of cardinals and pyi-rhuloxias on 

 a 42-acre tract 10 miles south of Tucson, Ariz. He reported that 

 their behavior is "basically very similar," and writes: 



With the break-up of winter flocks in late February and March, the males 

 of both species became highly pugnacious. This initial activity consisted pri- 

 marily of individuals chasing each other and it occurred within groups of up to 

 five birds. * * * Female pyrrhuloxias, but never female Cardinals, were noticed 

 to engage in chasing activities, often with the males. These chases apparently 

 establish a dominance order between the individuals so that the most aggressive 

 male succeeds in taking the best territory. * * * During late April and early 

 May definite territorial boundaries became established. As in the early stages 

 of this process, only the male Cardinal, but both the male and female Pyrrhuloxia 

 were involved. On one occasion a pair of Pyrrhuloxias was noticed moving about 

 an area which eventually became their territory. At one point another pair was 

 encountered and all four birds engaged in a vigorous fight. The intruding pair 

 was driven out and was never noticed to encroach on that area again.* * * 



