40 The Ornithology of Chester County 



October 10. 



42. Nycticorax nyticorax nycticorax Black-crown- 

 ed Night Heron, "crane," "Indian hen," "mudhen," 

 "mudpoke," "night heron," "qua-bird," "squawk." 

 Common summer resident, extremely local as a 

 breeder. Barnard considered it rare in his neigh- 

 borhood, and Montgomery never met with it in the 

 vicinity of West Chester. I have found it rather 

 common along the Octoraro below Atglen, and 

 Harry Wilson reports it probably nesting along 

 Buck run in East Fallowfield Twp., but I believe 

 that these birds are all from the Lancaster county 

 colonies. There is a large herony in the eastern 

 part of the Chester valley, in Tredyffrin Twp. 

 (Burns, Bird-Lore, xix, 197). Nidification begins 

 soon after arrival, average date for complete set, 

 May 10. Thomas notes its arrival at Kennett 

 Square, Apr. 12 (1908) Apr. 22 (1915), and it 

 doubtless averages several days earlier at its breed- 

 ing grounds than I am able to offer for Berwyn 

 vicinity : 



Arrival Apr. 15 (1917) Apr. 30 (1906) ; ave. 

 7 yrs. Apr. 20. 



Departure Oct. 6 (1911) Nov. 6 (1893); 

 ave. 3 yrs. Oct. 23. 



43. Nycticorax violacens Yellow-crowned Night 

 Heron. Rare summer resident. On May 14, 1915, 

 I found it present and evidently nesting in the 

 local colony of N.n.nycticorax. An individual, prob- 

 ably not always the same one; was observed circling 

 just above the tree tops on three occasions, and I had 

 a view of it through the glass while it perched close 



