166 



THE OOLOGIST. 



I Migration of Birds. 



Since the earliest times the subjectof 

 migration and seasonal movements of 

 birds has occupied the attention of 

 naturalists, and men wrote up».n this 

 subject over a thousand years ago. 

 And yet after all this time there are 

 many points which are still to be touch- 

 ed upon and several others still in dis- 

 pute. Naturally there were strange 

 stories regarding the misunderstood 

 disappearance of the birds in earlier 

 times and some of these superstitions 

 are still in vogue among the ignorant. 

 There are writers who still claim that 

 Swallows burrow in the mud in the 

 winter months. Many observers of 

 worth have evaded this subject in the 

 past while some naturalists over a 

 century ago scouted the idea that our 

 beautiful Swallows could hibernate in 

 the ooze and slime of the pond and bog. 

 In the main, observers are now agreed 

 that food requirements are the princi- 

 pal causes of the seasonal movments of 

 our birds, and not as is asserted by 

 some writers, the results of heat and 

 cold. 



Gilbert White of Selborne speaks of 

 the seasonal movements of the birds at 

 his point of observation in the lower 

 part of England as not so much depen- 

 dent upon heat and cold as upon con- 

 ditions of food supply. This worthy 

 man and close observer wrote nearly 

 one hundred and fifty years ago, yet 

 his good sense and charming style in 

 writing have secured him the enviable 

 reputation of a classical writer in the 

 branches which he wrote upon. 



This truth regarding the food supply 

 having greater influence upon a species 

 of bird than the cold, was nicely illus- 

 trated in the case of an escaped Cardi- 

 nal Grosbeak, which lived far to the 

 north of its usual winter quarters and 

 farther north than it is usually taken in 

 summer. This escaped bird though 

 reared in confinement, and we might 

 say ignorant of migrating habit, proved 



that it was able to thrive throughout 

 the colder months in the rigorous 

 weather in Michigan. This ability to 

 withstand the severity of the season 

 because it lived near to the houses of its 

 friends where it was provided with a 

 liberal supply of food. 



Many other Michigan birds that 

 seasonally leave us for the south, could 

 withstand the severity of the season if 

 provided with the proper food in their 

 winter quarters. The Robin, Meadow- 

 lark, Mourning Dove and more than a 

 score of other weil known species are 

 occasionally or quite one-third of the 

 seasons found with us throughout the 

 winter month or a portion of these 

 months; but this variation is not con- 

 stant at the north and indicates that 

 the requirements for food were met for 

 that season. These variable birds may 

 be classed as half hardy in making 

 out the list of our winter birds. 

 There are thirty-four species of these 

 half-hardy birds that our found with us 

 an occasional entire winter, or por- 

 tions of the winter almost every season. 



The well known Robin which is also 

 called the Migratory Thrush, is said to 

 frequently visit Central America in its 

 southern wanderings, and I have seen 

 them in the southern part of Florida in 

 February. But it is reasonable to think 

 that these extreme southern limits are 

 not taken by the most northern repre- 

 sentatives of summer in this land. I 

 believe that as a rule these extreme 

 southern wanderers are the summer 

 birds of Kentucky and Tennessee, and 

 birds of those latitudes; the general run 

 of Michigan birds probably not going 

 further south than the thirty-sixth par- 

 allel, while the Robins, which , dwell 

 with us in the southern part of the 

 Great Lake Region are representatives 

 or summer residents of sections three 

 or four hundred miles to the north. 

 Therefore, we may reason that the 

 Robins, Meadowlarks and others,— as 

 the little Song Sparrows are not really 



