HOUSE FINCH 299 



Supplementing the instance of pol^^gamy cited by Bailey and 

 Niedrach is the following case witnessed by Harold Michener (1925a) 

 in southern California: "On April 22, 1912, one male and two females 

 began building a nest on top of one of the beams supporting the roof of 

 the front porch. This position was sheltered by a wisteria vine. AH 

 three birds worked together in building the nest. Two eggs were in 

 the nest on April 28. Ten eggs were laid, one being crowded out of the 

 nest. After the fii'st part of the incubation period, during which there 

 were frequent contests between the females for the privilege of sitting 

 on the eggs, one of the females apparently disappeared and was seen no 

 more. The eggs had begun to hatch on May 12, but only six of them 

 hatched." 



Eggs. — The eggs of the house finch number from two to six, with 

 four or five comprising the usual set. They are ovate, sometimes 

 tending toward the elongated-ovate or short-ovate. The ground of 

 the egg is bluish white and they are delicately spotted, speckled, and 

 streaked, with comparatively few well-defined markings of "dark 

 olive," "mummy brown," or black. In most cases the spots are con- 

 fined to the top half of the egg, and often they form a very fine loose 

 ring around the large end. Occasionally an egg may be unmarked. 



The measurements of 50 eggs average 18.8 by 13.8 millimeters; the 

 eggs showing the four extremes measure 22.4 by 13.2, 16.7 by 13.7, 

 and 17.5 by 11.5 milhmeters. 



Young. — The incubation period as determined by Dr. Bergtold 

 (1913) in Denver averaged 14 days, but Chas. A. Keeler (1890b) re- 

 ported it as 13 days (presumably in northern California), while in 

 southern California the three sets most accurately timed by the 

 present writer agreed at 12 days. It thus appears possible that the 

 incubation period is shortened by a warmer climate. 



Evenden (1957) says the incubation period, timed from the laying 

 of the last egg to the hatching of the last egg, was 12 days each for two 

 nests in June, 13 days each for six nests, 14 da3^s for two nests, and 16 

 days for one nest in late April, early May. Hatching varied from one or 

 two birds per day for 3 days, to five young hatched in 1 day. Hatch- 

 ing dates were between May 1, 1954, and July 29, 1951. Circum- 

 stantial evidence indicates that the first egg laid hatched first. Hatch- 

 ing took place both during the night and in the daytime. Significant 

 differences in size of the young in the nests were observed infrequently. 

 The female carried eggshells at least 20 feet away almost imme- 

 diately — in fact, in one instance carried away one part of an eggshell 

 while the young bird was still in the other part. 



The development of the young is not quite as rapid as in some other 

 small passerine birds. Not until they are about 10 days old do the 

 young habitually hold their eyes open with an expression of alertness. 



