1913] Swarth: Geese of California 3 



Of the thirty-six specimens considered as hutchinsi (nos. 6497, 

 17241, 21961, 21980-21983, 21985-22013), twenty-five are males, eight 

 are females, and of three the sex was not ascertained. Six have a 

 white half collar at base of neck and a black line on throat, three have 

 white half collar with no black throat line, twelve have black throat 

 line with no white half collar, and thirteen have neither white collar 

 nor black throat line. Seventeen specimens have sixteen rectrices each, 

 while seven have eighteen. Tarsus and middle toe with claw are more 

 nearly the same size than in the other forms of the canadensis group. 

 Minimum and maximum measurements are: tarsus, 68 and 86 mm., 

 middle toe with claw 67 and 85. Usually the tarsus is a trifle the 

 longer. 



The descriptions of hutchinsi, as given in literature (e.g., Coues, 

 1903, p. 905; Ridgway, 1887, p. 117), characterize the form as of 

 smaller size than but otherwise similar to canadensis, giving no hint 

 of its intergradation with minima. Our series, as stated above, forms 

 an unbroken chain between the two forms. The series averages paler 

 than minima, many specimens being quite as light-colored as canaden- 

 sis, but there are few birds in the lot which combine the pale color, 

 and head and neck markings of canadensis with the smaller size of 

 typical hutchinsi, as should be the case. 



A possible explanation of the intermediate character of so many 

 of the birds wintering in California is that the breeding ground of 

 these variants lies in the region between the habitats of typical minima 

 and hutchinsi, and that there really is geographical continuity of range 

 in the summer home of the two forms, correlated with gradual blending 

 of characters in the birds occupying the middle ground. Then, if the 

 individuals wintering in California came from the more western part 

 of the summer home of hutchinsi as well as from all parts of the range 

 of minima, we should find here, as is actually the case, vast num- 

 bers of typical minima, a lesser number of intergrades, and compar- 

 atively few typical hutchinsi. On this supposition we shoidd expect 

 to find at points farther east but few intergrades and the majority of 

 birds typical of hutchinsi. 



The latest authority on the distribution of North American ducks 

 and geese (Cooke, 1906, pp. 77, 78) describes the subspecies minima 

 and hutchinsi as occupying in part the same region during the breed- 

 ing season, western Alaska and parts of the Aleutian Islands, a con- 

 dition that is certainly unusual unless the two are distinct species. 



