BREEDING BEHAVIOR OF SUCKERS AND MINNOWS. 15 



the pairing and moves upstream as though seeking an oppor- 

 tunity to pair unmolested. This she may secure and the pairing 

 then takes place in the manner already described. Although 

 supernumerary males may be present and may attempt to inter- 

 fere they take no part in the normal pairing. While they crowd 

 about the female and attempt to gain a place at her side, there 

 are no combats between them. When not at the side of the 

 female they seem to pay no attention to one another. 



When the breeding season is over the male suckers lose their 

 pearl organs. They were beginning to shed them in southern 

 Michigan on May 13, 1913. Both sexes become uniformly 

 olivaceous on sides and back. They are no longer commonly 

 seen on their breeding grounds, and in Michigan most of them 

 seek deeper waters. 1 



B. The Common Red-Horse (Moxostoma aureolum'Le Sueur). 



i. Breeding Grounds and Breeding Season. In southern 

 Michigan the red-horse breeds in May. My two dates are 

 May 17, 1904, and May 4, 1905. On these dates the breeding 

 season of the white sucker was nearing its end. While the breed- 

 ing grounds of the two species are the quieter, upper parts of 

 rapids in shallow water with gravel bottom and, while the two 

 species often breed in the same rapids, I have not found the 

 red-horse in streams as small as those sometimes frequented by 

 the breeding white sucker. The sucker may spawn in brooks 

 so small that one may step across them but I have found the 



1 In Walnut Lake Hankinson (1908) reports the species in water 15-40 ft. in 

 depth in summer and a few were found in a restricted part of the lake in water 80 ft- 

 in depth in April and May. I have found it in Douglas Lake, Cheboygan County, 

 Mich., from July to September in water up to 45 ft. in depth (Reighard, 1915). 

 Smallwood (unpublished notes) reports the return of suckers to Lake Clear after 

 breeding in Sucker Brook. On the other hand Forbes and Richardson (1908) say: 

 " It is with us essentially a species ot creeks and smaller rivers, nearly four times 

 as common, according to our data in the former as in the latter. . . . Our col- 

 lections show that it is much more likely to be abundant on bottoms with more 

 or less rock and sand than on a completely muddy bottom and that it has also a 

 decided preference for clear, swift water." Without a knowledge of the dates at 

 which Forbes and Richardson's collections were made or of the size of the fish 

 taken it is not possible to say to what extent adult suckers collected by them occur 

 on the rapids at other than the breeding season. Certain it is that they are abun- 

 dant in the deeper water of some inland lakes of Michigan and in the Great Lakes 

 when not breeding. 



