ORNITHOLOGIST 



AND- 



OOLOGIST. 



FRANK B. WEBSTER, Poblisheb. 



EstabliBhed, March, 1S7S. 



Single Copy 

 15 Cents. 



VOL. X. 



PAWTUCKET, R. I., JUNE, 1885. 



No. 6. 



Mississippi Valley Migration. 



BY PROF. W. W. COOKE, MOOKHEAD, MINN. 



Last montli we treated of migration during a 

 weeli in March, wlien the first wave was passing 

 over the Upper Mississippi Valley. This month 

 we take up a week in May, just before tlie close 

 of migration for the Spring. We have chosen 

 the seven days from May 4th to May 10th, 1884. 

 This includes two warm waves and an interim of 

 indeterminate nature. Of course, we find the 

 l)irds migrating under very different conditions, 

 and as a result a very different set of birds. We 

 look in vain for notes on Ducks, Geese, Robins, 

 itc, and in their stead we have the brilliantly 

 colored Orioles, Grosbeaks, Indigos and Tana- 

 gers. In the place of the frost and cold of 

 March, there is a Summer temperature, frostless 

 nights, and swarms of insects ready to hand for 

 the Warblers, Vireos and Flycatchers. But the 

 laws of atmospheric movements remain the same, 

 and the effect of these movements on the birds is 

 the same in kind, but slightly different in degree. 

 A north wind still retards their movements, but 

 it comes with no icy breath to chill their blood, 

 and when the fancy takes them, they move easily 

 against its no longer dreaded force. 



Our record begins at 11 p. m. , May 3d, and we 

 rind an area of low pressure in northwestern 

 Dakota and Manitoija, being very low, 29.38 

 inches at tJu'Appelle. Most of the Mississippi 

 Valley was included between 29.7 inches and 30.0 

 inches, the latter being the reading all along our 

 eastern border. This low area produced souther- 

 ly winds over most of our district; there being 

 nothing but S.S.E. and S.W. winds in the region 

 north of St. Louis. The temperature was high, 

 .58° to 61°, along the Mis.sissippi and the lower 

 Missouri to St. Paul and Omaha, falling to 5.5° at 

 St. Vincent and Bi.smarck, and falling rapidly 

 around the lakes to 43° at Marquette. South of 

 Milwaukee and Omaha it was cloudy, north of 

 there clear. During the night the low area 

 moves south to a little below Bismarck, the S. 



wind still blowing over the Mississippi Valley 

 with increased cloudiness in the northern part. 

 By 3 p. m., May 4th, West Los Aminas, Col., is 

 the center of the low area and there is a decided 

 fall in pressure over all the United States east of 

 the Rocky Mountains, causing the S. wind to 

 blow still harder, with clouds and local rains in 

 the Upper Mississippi Valley. Such was the 

 preparation for the bird wave of the night of 

 May 4th, for after 3 p. m., the low area turned 

 northeastward and passed directly across oiu- 

 upper district, being central at Yankton at lip. 

 m., with a pressure of 29.64 inches. It will be 

 seen then that all migration during the nights of 

 May 3d and 4th, was on a falling barometer, on 

 the night of the 4th with cloudiness, and on both 

 nights with warm southerly winds. 



in our study of migration in May we must 

 deal almost entirely with the 11 p. m., observa- 

 tions of the weather, for toward the latter end of 

 migration the movement is for the most part by 

 night. It is true that a few species like the 

 Warblers, for instance, move a little during the 

 day time, passing slowly from tree to tree, but 

 only short distances arc made in these journey- 

 ings, leaving the bulk of the movement to be 

 performed at night. 



During the night of May 3d, we find but a few 

 movements, and more than half of these arc 

 around St. Paul and northward, where the influ- 

 ence of the low area in Manitoba was already be- 

 ginning to be felt. The full advance was post- 

 poned until the next night, which was one of 

 great movement over most, if not all the country 

 from St. Louis to Manitoba. The districts which 

 furnished but nine records for the night of May 

 3d, on the next night show nearly seventy. The 

 wave seems to have been mo.st pi'onoimced in 

 Iowa, northern Illinois, southern Wisconsin and 

 at St. Louis, with a heavy wave at Manitoba, and 

 another in northern Texas, but it is not unlikely 

 that this seeming volume is somewhat due to the 

 greater number of observers in these parts. It 

 might be truly said of the records of this wave, 

 that in each district their number is about pro- 



Copyrigbt, 1885, by Fbanx B. Wzbsteb agd Eaton Curi'. 



s\>i\Oni 



