1642 U.S. NATIONAL MUSEUM BULLETIN 237 part 3 



Saskatchewan, the laying time, as nearly as we could determine, was 

 between 6:00 a.m. and 7:30 a.m., central standard time. 



Incubation generally does not start until the clutch is completed, 

 and is entirely by the female alone. Some confusion has resulted 

 apparently from the occurrence of male plumage characteristics in an 

 occasional female. 



The male spends his time during the incubation period in foraging, 

 singing, defending the territory against encroachment by neighboring 

 pairs, and chasing off small mammals and birds that approach the 

 nest. One male approached the incubating female with a mouthful 

 of insects, but was deterred by the close proximity of the blind. This 

 behavior was not seen again during many hours of watching and may 

 have been anomalous, perhaps anticipatory of later nestling feeding. 



As Harris (1944) notes, the male 



* * * selects one or two definite stations near the nest. He watches atten- 

 tively for his mate, and when she flies to or away from the nest, he follows and 

 alights beside her. Now and then throughout the day he launches himself into 

 the air, rises to a height of 10 to 50 feet, spreads wings stiffly, and, floating slowly 

 to earth, delivers his short, clear melody. At the approach of a human intruder, 

 the male retires to his favorite perch, from which he marks the intruder's progress. 

 With uneasiness growing stronger, he takes wing and flies back and forth over 

 his territory, giving utterance to a warning wheer note and sometimes a song. 

 Some males have a habit on these occasions of reaching the highest point of their 

 flight directly over the nest. 



As incubation progresses the female sits very closely and leaves the 

 nest only when almost trodden upon. Sometimes she flutters away 

 in a distraction display with half-spread wings as though crippled. 

 She leaves the nest of her own accord, however, every half hour or so 

 and joins the male feeding, or she may fly to a nearby pond for a 

 drink. If the female has not returned after a few minutes, the male 

 appears agitated and flies to the nest, or he chases the female until 

 she returns. 



DuBois (1935) found the incubation period at one nest to be 12% 

 days. Harris (1944) reports the period "from the laying of the last 

 egg to the hatching of the last" to be 10 days at three nests. Our 

 observations at one nest support DuBois's 12%-day period — the last 

 two marked eggs in a four-egg clutch were 12 days 13 hours, and 11 

 days 13 hours old the evening before they hatched. This is confirmed 

 also by Moriarty's (1965) timing of a marked clutch: "(2:30 p.m.). 

 Egg No. 1 was hatched, 14 days plus 6 hours after laying. This was 

 11 days and 6 hours after I was sure incubation started. Eggs No. 2 

 and No. 3 were pipped at this time and hatched, young still moist at 

 5:30 p.m. By this time No. 4 was pipped, to hatch and dry by 7 p.m. 

 It took about 1 to 1% hours to complete hatching after the egg was 

 pipped." 



