114 BULLETIN 17 4, UNITED STATES NATIONAL MUSEUM 



Straight minute. Nevertheless, he was greatly agitated, and would look out 

 every few seconds to see if the nuthatches were approaching, — his crown-patch 

 showing brightly. At last the male nuthatch came to the edge of the hole, whereat 

 the woodpecker made an unsuccessful attempt to peck his opponent, afterward 

 flying out with a rush, and chasing the nuthatch for some distance on the wing. 



Soon after that four Canada jays approaclied, and one of them 

 ventured near the nest hole, but the woodpecker and a hermit thrush 

 succeeded in driving him and his companions away, and they did not 

 return. 



Joseph Dixon (1927) tells of an attempt by a black bear to rob a 

 nest of young Arctic three-toed woodpeckers : 



This nest was located only four feet above the ground in a large live lodge- 

 pole pine. My attention was first attracted to the locality by the unusually 

 vigorous scolding of the parent woodpeckers. A closer approach revealed the 

 cause of the excitement. 



A bear had located the nest, probably through the noise of the young wood- 

 peckers, which were old enough to come to the nest entrance to receive food, 

 and which squealed with anticipation of a meal any time any bird, animal 

 or person came close to tlie nest tree. In an endeavor to get at the young in the 

 nest, the bear had bitten out slabs of green wood twelve inches long, two inches 

 wide, and one-quarter of an inch thick. The muddy stains around the inside of 

 the nest entrance showed that the bear had thrust his nose into the hole 

 repeatedly. But after gnawing over an area 10 by 10 inches on the tree trunk 

 to a depth of more than an inch, the bear gave it up as a bad job. Had the nest 

 been in an old stump, the outcome would probably have been different. This 

 offers a reasonable explanation of the tendency of certain woodpeckers to nest in 

 living trees. 



Mr. Kennard tells in his notes of a female hummingbird that at- 

 tacked one of these woodpeckers: "Several times she swooped down 

 at the woodpecker, who, quick as a flash, would dodge around the 

 trunk and out of her way." 



Winter. — The Arctic three-toed woodpecker is normally mainly 

 resident in winter throughout most of its breeding range; it is a 

 hardy bird and its food supply is available at all seasons, the grubs on 

 which it feeds remaining in the wood for more than one season. Prob- 

 ably a few wander southward nearly every winter, and there have been 

 several heavy flights of these birds into the Northeastern States, which 

 it is not easy to explain. Dr. Josselyn Van Tyne (1926) has given 

 a full account of one of these invasions, to which the reader is referred. 

 Mr. Forbush (1927) writes: 



It is difllcult to determine exactly what causes these unusual migrations, 

 They are not forced by inclement weather, for one at least has occurred in a mild 

 winter. * * * It seems probable that the unusual invasions of the species 

 into New England follow summers when its food has been unusually abundant. 

 An excessive food supply tends to fecundity, and overbreeding naturally compels 

 expansion and induces migration, whether among the lower animals or human- 

 kind. Since the above was written, Mr. Josselyn Van Tyne has published a 

 paper regarding the unusual flight of this species in 1923 in which he advances 



