BLACK-POLLED WARBLER 395 



the Arctic Circle. In the Mackenzie Delta region bordering the Arctic 

 Ocean the blackpoll is found in dense alder thickets in gullies and 

 ravines ; nesting some distance beyond the tree limit. A. K. Porsild 

 (1943) found a nest in an alder thicket near the water's edge on the 

 south end of Richards Island, off the Delta, on August 16, 1934. The 

 nest contained many feathers and was lined with the down of Epilo- 

 hium and willow. 



At Kent Island, New Brunswick, the blackpoUs usually arrive 

 during the last week of May, and they may be heard singing or be seen 

 feeding among the thick spruce growth which covers a large portion 

 of the 2-mile-long island. Courtship and nest building is a slow de- 

 liberate proceedure and nests with eggs are not to be found before the 

 second or third week of June. 



The major part of nest building was performed by the female, in 

 one instance under observation; the male was in full song during 

 this time, and while he may have assisted in gathering nesting mate- 

 rial I never saw him do any construction work at the nest. The nest 

 contained one egg on June 16, 1932, but it was not until June 22 that 

 the fifth and final egg of the set was laid. Two nests found by Ernest 

 Joy, warden at Kent Island, contained one Q,gg each on June 11, 1943. 

 Each set of five eggs was complete on June 15, indicating that in 

 these two cases an egg was laid each day until the sets were completed. 



The female sits very closely when incubating; by moving cautiously 

 I have approached within a few feet of the bird before she fluttered 

 away. At the New Hampshire Nature Camp, Lost River, N. H., in 

 the White Mountains, a blackpoll built a nest in a small spruce tree 

 standing alongside a trail used frequently each day by numerous 

 students. The incubating female paid no attention to passing persons 

 unless they stopped to examine the nest more closely. Wlien thus 

 forced to leave the nest, she slipped off into the dense growth of spruces 

 but emerged soon to utter sharp alarm notes. These calls invari- 

 ably brought the male to the scene, and together they would protest 

 the intrusion. The male guards his territory zealously and is ever 

 ready to challenge a bird of his own kind or any stranger that appears 

 in the vicinity. In addition to his singing and duties as guardian 

 I have seen him bring food to the female at the nest. One of the 

 best ways to locate a nest containing eggs is to follow a male carry- 

 ing some larvae or insect to his mate. A nest of course can be quite 

 easily located in this manner after it contains young, by watching 

 either parent. 



Dr. Herman R. Sweet made a study of nesting black-polled warblers 

 at Kent Island during the summer of 1933. His arrival at the island 

 was too late to observe their behavior during courtship, nest building, 

 or incubation, save for 2 hours spent in the blind erected within 4 



