1444 U.S. NATIONAL MUSEUM BULLETIN 237 part 3 



on June 2, 3, and 4. Further details of this nest are given in later 

 sections. 



Eggs. — Lincoln's sparrow lays from 3 to 6 eggs with 4 or 5 com- 

 prising the usual set. They are ovate with some tendency to elongate 

 ovate and are slightly glossy. The ground of freshly laid eggs is 

 "pale Niagara green," but this fades upon exposure to a greenish 

 white. The markings are of reddish browns such as "Verona brown," 

 "cinnamon brown," "Prout's brown," or "Argus brown." These are 

 usually heavy and may be in the form of fine speckles and spots or 

 large clouded blotches. Often the ground is entirely obscured and 

 appears to be a light brown. Some eggs may have undermarkings of 

 "pale neutral gray." They are practically indistinguishable from 

 those of the song sparrow, but in a series they will average slightly 

 smaller. The measurements of 130 of all three races average 19.4, 

 by 14.4 millimeters; the eggs showing the four extremes measure 21.6 

 by 14.9, 20.0 by 16.0, 17.2 by 13.5, and 18.0 by 13.2 millimeter. The 

 measurements of 50 eggs of M. I. lincolnii average 19.7 by 14.6 milli- 

 meters; the eggs showing the four extremes measure 21.6 by 14.9, 

 20.0 by 16.0, and 17.2 by 13.5 millimeters. 



Incubation. — The chief purpose of our studies at Dorion during 

 1956 and 1957 was to obtain information on the incubation and 

 fledging of Lincoln's sparrow, about which practically nothing had 

 been published prior to that time. 



Edward A. Preble (1908) wrote: During their trip to the Mac- 

 kenzie my brother and Cary noted it at Hay River, June 29, and 

 the following day found a nest containing five heavily incubated eggs. 

 The male bird was shot just after being flushed from the eggs, showing 

 that it assists in incubation." 



Nice (1943) cites six instances of male song sparrows seen visiting 

 the nest during the incubation period, but gives no record of actual 

 incubation by the male. She states that "only females regularly 

 incubate with * * * American Sparrows." In our studies at Dorion 

 we never saw a male Lincoln's sparrow incubating. 



In a nest we found on May 31, 1957, by the side of the entrance 

 road into the Dorion Trout-Rearing Station, the first, second and 

 third eggs were laid on June 1, 2, and 3 respectively. We marked 

 each egg as we discovered it in the nest using a grass blade dipped in 

 India ink. The final (fourth) egg was laid after 7:35 p.m. on June 3 

 and before 7:20 a.m. on June 4. An attentivity recorder in the nest 

 indicated that the female was on the nest during the night between 

 8:15 p.m. on June 3 and 2:22 a.m. on June 4, and again between 4:11 

 a.m. and 6:02 a.m. on June 4. On June 17 at 7:05 a.m. the nest con- 

 tained three young and the unhatched fourth egg. By 12:35 p.m. 

 the fourth egg had hatched. This established the incubation period of 



