404 Roosevelt Wild Life Bulletin 



other hand, the shadows of the taller trees may be grateful and 

 advantageous to birds when cast over their coverts during the heated 

 hours, producing cool retreats. Certainly a region lacking shaded 

 coverts would not be tolerable for many of our summer birds, since 

 it is customary for them to retire in the middle of the day into the 

 cool shrubbery for a siesta. Few birds are heard in the hot noon 

 hours, and fewer are seen. The woods are then silent and appear 

 deserted, and it is an unpromising time to observe their winged inhab- 

 itants, whose slight movements are then limited to the low, shaded 

 places. In an ordinary day in midsummer at Cranberry Lake, when 

 a thermometer exposed to the sun registers 85 F., the mercury will 

 fall to 65 ° when placed in shaded shrubbery. It is thus plain that 

 the taller trees bring about circumstances that cause a series of 

 adjustments in the daily life of the birds within their influence, lead- 

 ing them to regulate their movements so as to obtain favorable 

 degrees of protection, light, temperature and subsistence. Whatever 

 may be the value of light and shade as factors produced by tall, trees 

 in a habitat, any serious disturbance of the equilibrium resulting 

 from their daily alternation must necessarily result in new adjust- 

 ments of the birds to the changed conditions. 



3. The Habitation Clearing. This term is used to designate an 

 area of original woods from which the trees have been cleared by man 

 to provide a site for buildings, a garden, sawmill or lumber camp. 

 A clearing in this region is usually insignificant in extent compared 

 with the surroundings, hence it is a secondary factor introduced by 

 man into an avian habitat otherwise uniform. Any clearing, there- 

 fore, is an influence in the forest tending to restrict the dominance 

 of certain birds and to enlarge the range of others. A habitation 

 clearing, however, differs from an opening made by felling and 

 removing the timber in that it projects into the locality certain influ- 

 ences, offering attractions and inducements that do not always fol- 

 low the mere removal of trees. Buildings for the use of man and 

 his domestic animals, with their accompaniments, serve as an influ- 

 ence to repel certain birds and to attract others. In addition, there 

 are introduced into the clearing a number of foreign weeds and 

 grasses, such as clover, timothy, blue grass, mustard and other 

 seed-producing plants much patronized by birds as food, making 

 the vegetation so different from the original woods that it constitutes 

 a special habitat in itself. 



Back of the Summer Camp a short distance, in an easterly direc- 

 tion, is the site of an abandoned lumber camp (figure 124). Ruins 

 of log houses stand near the brook, and old trails lead thither. It 

 contains no tall trees, so that its whole area is in full illumination ; 

 it has, however, several tall dead snags and boles, more or less fire- 

 scarred (figure 125). Along the trails, and in open places where 

 bushes have not established themselves, timothy, blue grass, clovers 

 and ot*- er pasture grasses abound, with many of the weeds that thrive 

 under "cultivation. Interspersed everywhere in this clearing are ele- 

 ments of the aspen-fire cherry-birch association, with blackberry, 



