Shelter 79 



when they reach maturity are in accordance with the relations of 

 brood cover to adult cover. The younger the brood, the more strongly 

 is its tendency to adhere to brood-cover selection habits, and the 

 older the brood the greater the chance that the cover types selected 

 will follow adult habits. The high use intensity of overgrown land 

 is most prominent in the first six weeks, and drops off rapidly after 

 that time. Similarly, the use of the woodland types increases after 

 midsummer, except for that of coniferous woods, which does not 

 increase materially in use intensity until autumn. Slashings are used 

 rather consistently at all ages by the chicks, as would be expected 

 since the use intensity of slashings by the adults is about the same 

 as it is for the broods. 



CHANGES IN COVER TYPES UTILIZED AT DIFFERENT 

 TIMES OF DAY 



As is the case with the adults, the cover types used by the broods 

 vary considerably at different hours of the day. These changes are 

 the result of the needs of the birds for food, for roosting cover, for 

 dusting, or for sunny spots, all of which vary from morning to night; 

 and in many instances are the results of reactions to weather con- 

 ditions which vary according to time of day, notably the cold at 

 night and the heat at midday. 



The most important brood-cover type, overgrown land, shows a 

 marked increase in use intensity throughout the day, the use in 

 early morning being a little below, and that in late afternoon cor- 

 respondingly above, the mean. In slashings the tendency is toward 

 highest use at midday and early afternoon, and lowest use at late 

 afternoon. These trends in cover-type use by broods are at some 

 variance with the habits of the adults ( see page 92 ) . The old birds 

 use overgrown cover most in early morning, least at midday, and 

 normally in the afternoon; and slashings least in the morning, high- 

 est at midday. 



The use of hardwood woods increases from morning through mid- 

 afternoon, then drops off at evening. The latter trend is opposite to 

 the habit of adults of increasing the use of hardwoods towards eve- 

 ning. With mixed woods and conifers the trend is complementary 

 to the rest, a higher use intensity in the early day and falling off 

 later. 



