290 IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
mg lie could usually find a nest. It has seemed, in fact, that 
location of song and nest coincided to a marked degree, which 
soon led to the theory that possibly the bird sings on the nest 
Fig. 46. — During incubation both male and female had the habit of 
sitting motionless at the nest edge for periods of from ten to twenty min- 
utes at a time, this with an unusual frequency. 
as does the Warbling Yireo. Nothing had been published to 
this effect before 1911 when the writer told in Bird Lore of 
