720 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. IX. 



Eggs, 2 to 4. Size, 1.96 x 1.66. Eggs, pure white, not bluish white. 

 Nest in old crow's or hawk's nest, sometimes in hollow tree. 



Strix varia. 

 Barred Owl. 



Eggs, 2 to 3. Size, 2.20x1.82. Eggs, pure white; the size will 

 distinguish them from preceding species. Nest in old crow's or hawk's 

 nest, sometimes in hollow tree. Bubo virginianus. 



Great Horned Owl. 



SECTION 2. NEST IN HOLE IN TREE, STUMP, OR POST. 



PART i. EGGS LESS THAN .80 IN. LONG. 



Eggs, 4 to 7. Size, .75 x .53; shape, rather long and narrow. 



Iridoprocne bicolor. 

 Tree Swallow. 



Eggs, 4 to 6. Size, .75 x .60. Eggs rounded; the width will dis- 

 tinguish them from those of preceding species. Bird: if bird is seen, 

 no one can mistake a Woodpecker for a Swallow. 



Dryobates pubescens medianus. 

 Downy Woodpecker. 



PART 2. EGGS FROM .80 TO .98 IN. LONG. 



Eggs, 5 to 7. Size, .88 x .68. Bird: female, large; patch of black 

 on breast ; top of head, red ; no red on throat. A rather rare breeder. 



Sphyrapicus varius. 

 Yellow-bellied Woodpecker. 



Eggs, 4 to 6. Size, .92 x .74. Bird: female, throat and under parts, 

 pure white; crown, black. A common breeder. Dryobates villosus. 



Hairy Woodpecker. 



PART 3. EGGS FROM .98 TO 1.25 IN. LONG. 



Eggs, 3 to 5. Size, about i.oox.yo. The slight but noticeable 

 difference in size will distinguish them from those of the next species. 

 Bird: female, bluish black above (at a distance appears to be black), 

 grayish beneath; no yellow or red in- plumage. Male, entire plumage, 

 shiny blue-black. Progne subis. 



Purple Martin. 



Eggs, 4 to 6. Size, about i.oo x .76. Shape, more elongated and 

 narrower than next species. Bird, whole head and throat, red; wings 

 showing much white. Melanerpes erythrocephalus. 



Red-headed Woodpecker. 



Eggs, 5 to 10. Size, about i.io x .87. Bird, size, large; black 

 patch on breast ; under wings and tail, yellow ; no white on wings ; top 

 of head and throat, not red. (Female.) Colaptes duratus luteus. 



Northern Flicker. 



