• 1 20 



nl)sent the day before. Their departure was similar. On April 11, 

 17. '27 and May 1. the less A-agrant summer resident Profiiic was the 

 only Swallow remaining of the motley companies of the day before. 

 In other years this mode of migration has been just as marked; in 

 i;»02. tAvo species arrived together ou the tifth of A])ril and three on 

 the thirteenth: and in 1S85, four species, the Bank. Tree. Barn and 

 Cliff SwalloAvs an-ivcd in one liock on the ir>th of April, and were 

 seen together again on the next day. Tree and ("liff Swallows became 

 common on the 22d. the Barn Swallow a day Itefoi'e. and on the 25th 

 the Bank and Roughwinged Swallows became common. 



A more detailed discussion of the migration of the Ilbitndinid(£ 

 in 1903. ATill 1)ring out another point, i. e.. the relation of weather con- 

 ditions to the phases of the migratory movement. 



From April 10, the date when three species had arrived, to May 3. 

 inclusive, when the last flock of migrants was seen, there were .just 

 fifteen cloudy or rainy days, with an average temperature of 47° at 5 

 a. m., and ten clear days Avith a temperature of 44.° SAvalloAvs. some- 

 times, with the exception of the Purple Martin, were absent (three spec- 

 imens of HiniiiiJo seen one day and two of /'rtrocJicIidon another] during 

 the ten days, and Avere very much in evidence fifteen days. South Avinds 

 prevailed during this period and migration AA-as high among all the small 

 land birds, especially on the 2Sth and 2nth: Init on these dates no tlocks 

 of SAvallows Avere seen. If a clear or partly clear period was succeeded by 

 a rainy, cloudy, or misty one, swalloAVs AA-ere surely to be found. 

 As long as the Aveather remained cloudy, these birds remained, but ou 

 the first fair day they disappeared. The only species that arrived on a 

 clear day Avas the Tree SAvalloAv; but after its arrival its movements 

 agreed AA-ith those of its cousins. There was only one cloudy day on 

 which the croAvds of sAvallows Avere al)sent and even that day brought 

 an increase in the number of Martins. 



A synopsis of the period folloAvs: April 10. cloudy, 3 species; April 11. 

 cloudy, an increase in number of Purple Martins: April 12. fair, no Swal- 

 loAvs (Martin ignored); April 13-16, inclusive, cloudy and rainy, all species 

 present; April 17-18, clear, no SAvallows; 19-25. inclusive, cloudy or rainy. 

 all species present in considera1)le numbers; 26-29, fair, few SAvallows 

 seen and their number decreased during this period; April 30. cloudy, 

 a large flock of four kinds; May 1-2, clear, no Swallows; May 3. rainy, a 



9— A. OF SciKXCK, '04. 



