KEYES AND WILLIAMS BIRDS OF IOWA. 147 



Eggs similar to those of P. erythremias. Both birds came within a 

 dozen feet of the intruder, and were distinctly seen. The absence of 

 the black of the tail and wings of the male and the whitish bill were 

 points noticed as unequivocally distinguishing this species from its near 

 relative. The other two nests each contained three eggs, and were 

 taken in the immediate vicinity of the one just mentioned. 



Family HIRUNDINID^E. Swallows. 

 Genus PROGNE Boie. 

 [B 231, R 152, C 165, U611.] 

 Prague subis (Linn.). Purple Martin. Summer resident; abun- 

 dant. In central Iowa it usually arrives the last week in March, and 

 departs before the middle of September. The eggs are laid the last of 

 May. After the young are fledged the birds assemble in flocks, usually 

 selecting some large dead tree as a place of rendezvous, the young 

 birds remaining most of the time on the tree, and are fed by the old 

 ones. This is continued until the young are able to take extended 

 flights. They constantly increase in numbers until they depart for the 

 south. A marked instance of this kind occurred at Des Moines in 

 1884. Towards the last of August, the martins began to gather around 

 the spire of the First Methodist Episcopal Church. Their numbers 

 daily increased until there were many hundreds. For several days the 

 spire was literally black with the birds clinging to the sides and to 

 every projection that afforded them a support. Many were continually 

 dropping off and sailing away for a short flight, while others took pos- 

 session of the places vacated. They remained in this way for several 

 days, and then suddenly took their departure — for the next day not a 

 bird was seen. After the flock had disappeared but few martins were 

 noticed, and they were stragglers from elsewhere. 



Genus PETROCHELIDON Cabanis. 

 [B 226, R 153, C 162, U 612.] 

 Petrochelidon lunifrons (Say.). Cliff Swallow. Summer resident; 

 abundant from the first week in May until September. It nests in 

 large colonies, under the eaves of barns and old mills. Nidification 

 commences about the 20th of May. It is frequently noticed flying 

 about over the prairies, far away from any habitation. 



Genus CHELIDON Forster. 



[B225, R 154, C 159, U 613.] 

 Chelidon erythrogaster (Bodd.). Barn SwalloV. Summer resident; 

 common, but apparently somewhat irregular in its distribution. Arrives 

 the middle of April, and remains until the middle of September. The 



