76 SIXTEENTH REPORT. 



had been constructed many years previously, and which, while mere ves- 

 tiges overgrown with young trees and bushes, were more open than the rest 

 of the swamp. As one left these roads and entered deeper into the recesses 

 of the swamps, he found very few species and individuals of birds. The 

 chickadee was the commonest, the white-throated sparrow, winter wren 

 and Canada ruffed grouse being characteristic too, but less frequently noted, 

 5. The Mud Flats along the Rivers — The mud flats along the rivers were 

 too limited in number and area to play an important part in the local distri- 

 bution, l^ut formed a habitat so distinct from all others as to be worthy of 

 recognition. They consisted of small isolated patches of bare mud and 

 drift wood, often of an area of only a few square feet, quite too small to 

 furnish feeding grounds to any number of waders, and were submerged com- 

 pletely with the rise of the river coincident with rains. The spotted sand- 

 piper fed along them, later solitary sandpipers lingered a time on their 

 scanty expenses, while the bronzed grackles in little flocks took advantage of 

 the feeding grounds afforded by the larger flats just below camp. 



MIGRATION. 



As before stated but little migration took place previous to our departure 

 from the region. A few flocks of sandpipers that appeared July 29 were 

 the first real migrants; the middle of August saw a flight of sparrow hawks, 

 and later large flocks of warblers were noted along the Sturgeon River, and 

 in the hardwood forest. It is very probable that these latter flocks were 

 in reality gatherings of local residents rather than migrating birds. These 

 flocks began to appear commonly August 18 and 19. A flight or two of swal- 

 lows and a single large flight of chimney swifts about completes the migra- 

 tion noted though certain observations are recorded in the list of species 

 under various other forms. 



EFFECTS OF THE BURN ON THE LOCAL DISTRIBUTION OF THE BIRDS. 



Certain effects of the burn were most noticeable. It excluded some spe- 

 cies that must otherwise have been present, and favored the introduction 

 of others by influencing food, nesting sites and enemies, and it effected the 

 birds both in their breeding and migration seasons. Very interesting are the 

 species favored by the burn. They fall directly into two classes, those fur- 

 nished with suitable breeding conditions and those supplied with well provi- 

 sioned halting places during migration. 



In the first of these classes — those species which found especially suitable 

 breeding conditions both in an abundance of favorable nesting sites and 

 abundant food as a result of the burn — were the woodpeckers, the tree 

 swallows, the chimney swifts and the bluebirds. Large numbers of tall 

 dead trees particularly along the rivers, were soft and punky from decay 

 and the wood in this condition is filled with larvae that are easily accessible, 

 and it was easily excavated to form nests. The result was an abundance 

 of woodpeckers, particularly the downy, which took advantage of food and 

 nesting sites so closely approximated. Even more conspicuous was the 

 case of the tree swallow, which was influenced by the abundance of wood- 

 peckers as well as by the burn, since it found numbers of suitable nesting 

 sites in the abandoned woodpecker holes and an abundance of flying in- 

 sects over the water. Consequently the species was abundant, and along 

 the river there were so many colonies that almost every dead tree was in- 

 habited, and, especially when the young emerged, the species dominated the 



