° 1915" J Cooke, Bird Migration in the Mackenzie Valley. 4ol 



the lakes and marshes of the Mackenzie Valley, come from the 

 moister portions of the Mississippi Valley. 



With regard to the nine species of migratory hawks and owls of 

 wide range that visit Lake Athabaska nothing can be judged at 

 present either from distribution or migration as to the route or 

 routes they employ. Fifteen species of the smaller migratory land 

 birds have the same range and in some cases, the dates of migration 

 afford a hint of the route traveled. Thus in the case of the Crow, 

 the dates of migration show clearly that the earliest individuals to 

 reach southwestern Manitoba come not from South Dakota as 

 would be expected, but from the timbered regions of Minnesota. 

 The date of arrival at latitude fifty degrees in southwestern Mani- 

 toba is March 27, as determined by fourteen years' observations 

 from four neighboring towns. March 27 is a fair average date for 

 the arrival of the Crow in east central South Dakota, three hundred 

 and fifty miles to the southward; while the average date of arrival 

 in southern North Dakota is a week later than in Manitoba. Con- 

 tinuing in the same general northwestern course it is probable that 

 the Crows appearing April 2, 1893, at Osier, Saskatchewan came 

 from Manitoba rather than from Montana; since this date would 

 be considered an early date of arrival in southeastern Montana. 

 In this manner the dates of migration show that the earliest Crows 

 in the Mackenzie Valley come from the wooded districts of the 

 Mississippi Valley. 



The Myrtle Warbler presents a quite similar set of dates. This 

 species ranges from the Mississippi Valley throughout the Rocky 

 Mountains and to the Pacific, becoming much rarer west of the 

 mountains. In its spring migration, it reaches southern Manitoba 

 April 23, at about the same time as its first appearance in central 

 Nebraska and northern Colorado, showing conclusively that the 

 Manitoba birds come from the southeast. It is equally sure that 

 the arrival at Osier, Sask. latitude fifty degrees May 4, 1893, came 

 from the southeast, for this is the usual time of arrival in central 

 Montana latitude forty-seven degrees. Farther north a new possi- 

 bility presents itself, since the May 16 birds of Lake Athabaska 

 might, as far as the date is concerned, have come from British 

 Columbia in the southern portion of which Province they arrive 

 the middle of April. To determine this latter point use can be 



