190 The Ruffed Grouse 



hard pressed to get food, but it rarely lasts long enough to affect 

 them seriously, as they can go several days without food and suffer 

 no apparent ill effects. 



POPULATION FLUCTUATIONS AFFECTED BY 

 WEATHER CONDITIONS 



We have already noted instances in grouse trends where extreme 

 weather conditions resulted either directly or indirectly in abnormal 

 grouse losses. How great a part such meteorological extremes have 

 played in causing or precipitating the large grouse declines of for- 

 mer years cannot be gauged by these observations, but they do 

 indicate the possibilities inherent in climatic factors. As we have 

 already noted, Woodruff ( 1907 ) gave "the extremely cold, wet, and 

 late spring of 1907" as second in his list of three factors that caused 

 the decline of that year. Forbush (1912) likewise correlated the 

 1907 grouse collapse with bad weather. 



Knowing rather accurately when some of the most extraordinary 

 grouse reductions have taken place in New York and other parts of 

 the Northeast, we have examined the Weather Bureau records for 

 New York State in an attempt to ferret out any broad correlations 

 that might exist and the results seem too significant to be accidental. 

 The temperature and precipitation records are adequate as far back 

 as 1890, and sunshine data are available since 1909, The period 

 from 1890 to date covers four major and three minor grouse declines 

 in this state. 



If a certain weather condition, or a combination of conditions, 

 could explain important decreases in the grouse population, presum- 

 ably severe instances of those circumstances would occur during 

 all years of these decreases and in no others. However, no single 

 weather factor does this, nor does any combination completely agree. 

 But the coincidence between periods of grouse decline and certain 

 severe weather conditions seems too close to be wholly accidental. 



Since 1890 there have been four primary periods of sharply de- 

 creasing grouse abundance, approximating the years 1896-97, 1907, 

 1916-17, and 1927. Minor declines occurred in 1904, 1924 and 1935- 

 37. The evidence indicates that serious trouble from adverse weather 

 occurs from February to July and we may therefore confine our 

 analysis to these months. 



