Shelter 97 



use of heavy shelter types in stormy weather and a greater use of 

 the more open type^ in clear weather. 



Cover Type Use as Affected by Wind. The strength of wind, with- 

 out respect to direction, may be noted as either still, moderate, or 

 strong. When the air is entirely quiet or with just an appreciable 

 movement, it is called still; when gusty or an average light blow, it 

 receives the designation of moderate; when the wind rises to stormy 

 strength, probably exceeding twenty miles per hour, it is strong. 

 The evidence shows clearly that a strong wind, as compared to a 

 lack of vraid, produces very significant differences in predominance 

 of cover types selected. While it is not possible fully to separate the 

 relative effects of the different elements of the weather, all acting 

 at once as they do, it is probable that wind is nearly as important as 

 sky condition in determining grouse use of cover types. Surely it is 

 a more prominent factor than temperature at its extremes. 



More than that of any other factor, the effect of wind is con- 

 sistent throughout the year. Strong winds bring an increased use 

 of overgrown land (particularly popple stands) at all seasons and 

 of coniferous woods from fall through spring, and lessened utiliza- 

 tion of mixed woodland at all seasons and other types at some 

 seasons. In still weather, especially in summer, the most notable 

 shift is to hardwoods. 



In analyzing the effect of weather on cover type selection, we 

 have separated the three most effective weather elements and con- 

 sidered them separately. This simplified the analysis but actually, of 

 course, the weather factors all occur together, and hence we should 

 consider what cover is used when the several factors occur in the 

 various combinations. To do this would require long and relativelv 

 unproductive analysis. We have noted that sky condition appears 

 to be the more dominating element, wind following closely, and 

 temperature trailing. However, it is also true that extremes, whether 

 of one factor or another, tend to be the determining element. Thus, 

 on a clear, quiet, and hot summer day, the temperature may de- 

 termine the cover a bird will select; or on a very windy day, with 

 cloudy skies and normal temperatures, the wind will be the guid- 

 ing element. When extremes of similar direction occur together, as 

 a snowy, windy, cold day, it makes little difference which elements 

 dominate the consideration since all bring the same result. 



