2 2 2 Jones, Bird Migration in lovja. \\^ 



birds in all sorts of dress. For almost all birds are in their 

 plainest attire on their journey southward. Then birds are wary 

 and timid, instead of bold and fearless. No songs announce their 

 arrival. All is quiet. 



The majority of records in spring are of arriving birds. In the 

 fall they are of departing birds. No records are more difficult to 

 make accurately than those of the departing birds. A great deal 

 of time was spent in the field in the fall, but the records are 

 always fewer than those of spring. 



We have seen that the weather greatly affects the spring move- 

 ments of the birds, severe and adverse winds combining with 

 inclement weather to retard the northward movement. In the 

 fall tlie weather has an opposite effect. Late in the fall this is 

 more apparent and of much more significance than early. 



The charts for the fall migrations are made on the same general 

 plan as those for the spring migration, with the addition of a 

 weather record at the top, represented by a sinuous line. The 

 downward curves indicate the occurrence of a falling temperature' 

 and cold northerly winds. A rise in the line indicates a rise in 

 temperature and southerly winds. 



A study of the charts makes the relation of the bird movements 

 to the weather clear. Each di|) of the line representing the 

 weather is accompanied by a corresponding activity among the 

 birds. There is either an influx of more northern species or an 

 efflux of summer residents, or both combined. Usually it is of 

 both combined. Frequently the movement follows the unfavor- 

 able weather; sometimes it slightly precedes it. Warm days and 

 south winds retard the southward movement instead of accelerat- 

 ing it, as in the spring. 



August is marked by almost uniformly warm weather, there 

 being no marked changes from warm to cold. Yet some birds 

 move south even in August. These are the Yellow-breasted Chat 

 and -Yellow Warbler, with a possible migrant or two from the 

 north. The movement is not well marked. 



Our first evident movement occurs early in September, when 

 the first breath of winter is felt. Then there is not only a marked 

 efflux of summer residents, but an influx of northern species. It 

 will b'.' noticed that the birds moving at this time are those which 



