of South America just about the time that the earliest of those breeding 

 in the North reach Florida on their way to winter quarters. 



Nocturnal and diurnal migration 



When one recalls that most birds appear to be more or less helpless 

 in the dark, it seems remarkable that many should select the night 

 hours for extended travel. Among those that do, however, are the 

 great hosts of shore birds, rails, flycatchers, orioles, most of the great 

 family of sparrows, the warblers, vireos, and thrushes, and in fact, the 

 majority of small birds. That it is common to find woods and fields 

 on one day almost barren of bird life, and on the following day filled 

 with sparrows, warblers, and thrushes, would indicate the arrival of 

 migrants during the night. Sportsmen sitting in their "blinds" 

 frequently observe the passage of flocks of ducks and geese, but great 

 numbers of these birds also pass through at night, the clarion call of 

 the Canada goose, or the conversational gabbling of a flock of ducks 

 being common night sounds in spring and fall in many parts of the 

 country. The sibilant, nocturnal calls of the upland plover or Bar- 

 tramian sandpiper and of other shore birds during their spring and fall 

 flights form vivid memories in the minds of many students of migra- 

 tion. Observations made with telescopes focused on the full moon 

 have shown processions of birds, one observer estimating that birds 

 passed his point of observation at the rate of 9,000 an hour, which gives 

 some indication of the numbers of birds that are in the air during some 

 of the nights when migration is at its height. While the steady night- 

 long passage of migratory birds has been recorded, the bulk of the flocks 

 pass during the earlier hours of the evening and toward daylight in 

 the morning, the periods from 8 o'clock to midnight and from 4 to 6 

 a. m. seeming to be favorite times for nocturnal flight. 



It has been claimed, with some reason, that small birds migrate by 

 night the better to avoid their enemies, and that most of the nocturnal 

 travelers are those that are naturally timid, sedentary, or feeble-winged. 

 To a certain extent this may be true as included in this group are not 

 only such weak fliers as the rails but also the small song and insectivor- 

 ous birds such as the wrens, the small woodland flycatchers, and other 

 species which, living habitually more or less in concealment, are prob- 

 ably much safer making their flights under the protecting cloak of 

 darkness. Nevertheless, it must be remembered that night migrants 

 include also the snipe, sandpipers, and plovers, birds that are always 



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