LIFE HISTORIES OF KORTH AMERICAN DIVING BIRDS. 161 



The habit possessed by the black guillemot of dabbling with its bill at the 

 water may have arisen in attempts to obtain food or to sip the water, but it 

 has apparently degenerated into a nervous trick devoid of useful purpose, like 

 the tail wagging of pipits and other birds. When disturbed by the approach 

 of a boat, black guillemots often dab frequently at the water as if in nervous 

 trepidation before taking flight. In rising from the water the feet are used 

 as an aid, and strike back the water one after the other alternately. Black 

 guillemots often chase one another in play or in passion, and make the water 

 boil as they dodge in and out above and below the surface with much flapping 

 of wings and spreading of tails as they thrust with their pointed bills. 



Winte7\ — As soon as the young are able to ^y, the black guillemots 

 desert their breeding grounds and frequent during the winter the 

 rocky shores of the north Atlantic coasts from Greenland to Long 

 Island, though they are rare south of Cape Cod. They are very shy 

 at this season and are usually scattered about in small parties or 

 pairs, playing in the surf off the rocky beaches or even well out at sea. 



DISTRIBUTION. 



Breeding range. — Coasts of northeastern North America and north- 

 western Europe. From Maine (Matinicus Rock, eastward), New 

 Brunswick (Grand Manan), and Nova Scotia (Seal Island) north 

 to Labrador and southern Greenland (Holsteinborg, probably rarely 

 to Disco Bay) . Also from Iceland, the Faroe Islands, Orkneys, Shet- 

 lands, and some of the Hebrides, northern Scotland, Ireland, and 

 Wales (formerly) east to Scandinavia and the White Sea. South 

 to Denmark, 



Winter range. — Slightly south of its summer home. Many remain 

 as far north as southwestern Greenland (Ivigtut) and few pass 

 south of Massachusetts. There is one record for Connecticut, one 

 definite and several indefinite records from Long Island, and it has 

 been supposed to occur on the Delaware River several times, but 

 there is apparently but one recent definite record. It is also said 

 to have been taken in Lancaster and Perry Counties, Pennsylvania, 

 and once on Lake Ontario, New York. A bird taken at Toronto, 

 Ontario, may be mandti. In Europe as far north as Norway and 

 south rarely to northern France. 



Spring migration . — Birds wintering on the Massachusetts coast 

 pass northward in April (April 11 to 19) ; occasionally individuals 

 linger till May. 



Fall migration. — Fall migrants arrive on the Massachusetts coast 

 early in November (November 5) ; rarely as early as September. 



Egg dates. — Maine: 25 records, June 12 to July 16; 13 records, 

 June 18 to 30. Bay of Fundy and Nova Scotia : 25 records, June 11 

 to July 6; 13 records, June 20 to 28. Gulf of St. Lawrence: 13 

 records, June 8 to July 15 ; 7 records, June 15 to 25. Great Britain : 

 11 records, May 23 to June 17; 6 records, June 5 to 11. Labrador, 

 east coast : 7 records, July 1 to August 2 ; 4 records, July 12 to 17. 



