TRICOLORED REDWING 181 



breeding range in California, and his counts and estimates seem to have 

 been made more accurately than some others. He makes the following 

 general statement: "The writer has noted almost every possible 

 variation in density of population. Twelve nests were observed in 

 one small willow, and thirty-six were counted in one clump of about 

 four tall willows growing from the same root. In cattails, nests have 

 been noted at least as numerous as one to each three square feet; 

 from one stand in thick cattails, without moving the feet except to 

 rotate, we counted from sixteen to thirty-six nests; the average of 

 many counts ran well over twenty. A count made in a marginal 

 colony averaged one nest to each nine square feet. In another colony 

 sample counts, in a number of ten-foot squares, ranged from sixteen 

 to thirty-four nests." 



His tables, showing the variation in sizes of different colonies, are 

 quite enlightening, the numbers running from less than a hundred to 

 over two hundred thousand nests in a colony. Some of his descrip- 

 tions of various colonies follow: 



About twenty miles east of Sacramento a reservoir, on what is known as the 

 Nimbus Ranch, owned by the Natomas Company, was dammed or dug, about 

 1912, as a source of water supply for gold dredgers. Cattail and tule developed 

 about 1916, and since 1920 or 1921 blackbirds have inhabited the area in great 

 numbers. Marsh growth in 1932 covered 30 to 40 acres. On March 4, 1932, 

 the roosting population of this area estimated at "nearly a half-million birds," 

 fed over an area fully forty miles in diameter. By April 25, 1932, nesting was 

 under way, and by May 1 many of the nests held full sets of eggs. In May 1932, 

 many trips were made to this marsh, and the estimate of several cooperators was 

 placed at 100,000 nests. * * * By 1935, dredgers had so changed the terrain that 

 only 2,000 to 3,000 returned to this place; the feeding area was too far away. In 

 1936 this locality was deserted; three smaller marshes a few miles away were den- 

 sely occupied by a population totaling about 100,000. 



On April 30, 1932, at a point five miles west of Watsonville, Piper found a 

 colony of about 1,000 Tri-colors nesting in a rather dry marshy area; there was 

 no standing water, but there was a thick tangle of blackberry vines, nettles, and 

 rather sparse cattails. Nests were uniformly in early stages of construction, with 

 no eggs. 



On May 14 and 15, 1932, Gabrielson and Jacobsen found a nesting colony in 

 a patch of thistles on a small slough about fifteen miles northwest of Merced on 

 the Crane Ranch road. The thistle patch was from 75 to 125 feet wide, forming 

 an almost impenetrable jungle. Nests held eggs or young. These observers 

 estimated that the birds numbered between 60,000 and 75,000 pairs. 



On May 19, 1933, the writer discovered a huge flight of Tri-colors on the hold- 

 ings of the Dodge Land Company and the Perriott Grant ranch which overlap 

 the Glenn-Colusa county line northeast of Butte City. Here there are a number 

 of sloughs which are not continuously filled with water; their width varies greatly 

 and it is virtually impossible to estimate the total area. On May 30, 1933, tens 

 of thousands of birds were flying back and forth into the cattails and tules in these 

 sloughs, carrying nesting materials. The birds were active over an area roughly 

 four miles east and west by six miles north and south. The number of birds, 

 apparently all nesting in the slough area, was so far beyond comprehension that 



