SUPPLEMENT TO BIRDS OF ESSEX COUNTY 43 



the air and catch it again, either in play or to get a better hold. The adults often 

 fly threateningly to within a short distance of an intruder on Ipswich Beach as 

 they do on the breeding-grounds, uttering sharp kik kik notes followed by a loud 

 rattling of the mandibles. 



In the original Memoir I gave an instance of a Common Tern chasing a 

 Sharp-shinned Hawk. On another occasion I saw one being chased by, and in 

 turn chasing, a Barn Swallow over the beach. On another occasion I saw six 

 Common Terns chasing two Crows that were hurriedly flying for the shore from 

 high over the sea at Ipswich. Occasionally a tern would dart down at a Crow 

 who would accelerate his flight for the shore. 



I visited Milk Island near Thatcher's Island off Cape Ann, on June 15, 1919, 

 and found nine pairs of Common Terns flying about the pebbly and rocky beach 

 on the eastern side of the island. They acted as if they were nesting, screaming 

 and darting down at me. I found only one nest which was well made of dry 

 grasses and weed-stalks and contained two eggs. One of these was the usual 

 kind, olive gray with chocolate-brown markings while the other was pale blue 

 and destitute of any markings. As far as I know this is the only place where 

 terns breed within the limits of the County. 



29 [71] Sterna paradisaea Briinn. 



Arctic Tern. 



Not uncommon transient visitor, formerly summer resident. Spring; July 

 31 to September — . 



30 [72] Sterna dougeilli Montag. 



Roseate Tern. 



Abundant transient visitor; formerly summer resident. July 11 to Sep- 

 tember 16. 



The successful result of the efforts of the Audubon Society in saving terns 

 from the slaughter and the milliner are strikingly shown in the case of the Roseate 

 Tern. Practically unknown on the Essex County coast for nearly forty years, 

 the bird is now abundant at times in the summer. I have recently described their 

 abundance, habits and field-marks in the pages of the Auk.^ In a few words it 

 may be said that the Roseate Tern appears whiter than the Common Tern and it 



1 Townsend, C. W. Auk, vol. 35, p. 182, 1918. 



