ZoO General Notes. [April 



Squibnocket Pond, Chilmark, Mass., a very interesting fact was brought 

 to light, namely, that no Red-legged Black Ducks resort to this region, 

 and this experience was so different from that to which we are accustomed 

 in any of the eastern Massachusetts ponds, where Black Ducks are shot 

 through the entire season, that it seemed worth while to record it. It is 

 of especial interest because it brings out the different habits of the two 

 forms. 



The south shore of Martha's Vineyard Isle consists in the main of a 

 chain of fresh, brackish, and salt ponds, separated from the sea by a 

 beach. There are no salt marshes proper, and no tidal flats off the shore. 

 In many of these ponds there is excellent feeding ground for diving ducks, 

 but not much shallow ground for surface feeders. Nevertheless a goodly 

 number of Black Ducks resort to Squibnockett, using it as a day-time 

 refuge, and flighting to small sloughs scattered through the pastures and 

 uplands at night. Squibnocket is entirely fresh. The ducks have been 

 systematically baited there for many years and a number of pairs breed. 

 On August 20 last there were some 250 to 300 Black Ducks and on Sep- 

 tember 15 this number had not increased greatly. On September 20 

 some 600 were counted and by early October they had about doubled. 

 After the 10th of October it did not appear that there was any increase; 

 and the same number persisted until driven away by the big freeze of 

 December 12, 13, and 14, 1919. 



Black Ducks were shot on the following dates: September 23, 24; 

 October 14, 22; November 6, 7, 14, 21, 25; December 1, 4, 7, 8, 9, 10. 

 In all, 224 were taken during the season, and all of these, except 28, I 

 examined personally. There was no marked change in the appearance 

 of these ducks as the season advanced. In some of the mlaes the color 

 of the legs increased slightly in richness, but never approached the coral 

 red of rubripes. No other rubripes characters were noted. The average 

 weight of the males in mid-October was 2.86 pounds and the females 

 averaged 2.43 pounds. By December 10 these weights had increased to 

 3.24 in the males and 2.66 in the females, a very high average, induced 

 no doubt by artificial feeding. 



This body of birds became almost sedentary in its habits as the season 

 advanced, and when not disturbed they spent almost the entire day asleep 

 on the beaches at the west end of the pond. Even when greatly disturbed 

 they seemed loth to go to sea, although it meant a flight of only a couple 

 of hundred yards. They seldom remained long in the ocean. At night 

 many of these ducks resorted to small bog holes scattered through the 

 pastures, up to the time when ice made this impossible. 



It is fair to presume that nearly all these ducks would have passed 

 south early in the season if they had not been attracted and held by grain. 

 The absence of the tidal flats and marshes of course explains the non- 

 appearance of rubripes, but that there should be such a sharp line of 

 demarkation between the two forms at any one place seemed hardly 

 possible. 



