BREEDING HABITS. 67 



a newly filled, rounded grave. The fertilized ova Ue in the interstices of the stones and 

 coarse gravel at an average depth of ten inches. 



'Previous to spawning, the female prepares the initial hollow for the reception of the 

 eggs. Apparently the male has no share in this labor. This preparatory stage usually 

 occurs shortly before the salmon is ready to extrude her eggs, but it has also been ob- 

 served in females long before their eggs were ripe. The digging of the redd is an operation 

 distinct from the act of spawning. It is not usually accompanied by the extrusion of the 

 eggs, at least not until a suitable hollow has been made. After the selection of a suitable 

 site the female salmon begins the work of excavation by a vigorous action of the tail and 

 body. By powerful movement a column of water is forced against the bottom sufficient 

 to dislodge sand, gravel, and small stones, which are rolled downstream by the action 

 of the current. In this way an excavation is formed. The salmon, by intermittent 

 digging, enlarges the hollow, working on the sides and upstream end. 



'Mating: When ready to spawn, the female salmon selects a favored male and will aid 

 him in chasing away other amorous males, although she will not go far from the redd. 

 In making her choice she favors the large males and is intolerant of small males and 

 grilse. The favored male takes up his position directly downstream, a few feet below 

 the female, moving occasionally from side to side. The role of favored male is not secure, 

 since he may be supplanted at any time during the season, day, or hour. When there is 

 a surplus of males on the spawning grounds, cruising males are constantly shifting from 

 female to female, awaiting the crucial moment when they may share in the fertilization 

 of the eggs. Not infrequently two and even three males may temporarily occupy 

 secondary positions below a female. Whenever surplus males are on hand, the favored 

 male must share with others the privilege of fertihzing the eggs. 



'The favorite time for spawning is at night, but a few female salmon may be found at 

 any time of day digging the redd or, more rarely, depositing eggs. During the spawning 

 season, numerous vacant redds may be seen during the day on the gravel bars. 



'The older writers state that in the act of spawning the female salmon digs with her 

 flexed body and extrudes a few eggs, which are swept along with the displaced gravel. 

 The male then takes her place or lies beside her and sheds his milt over the eggs. The 

 alternate extrusion of eggs and milt continues with the digging of the female until a 

 considerable heap of gravel has been formed. The female salmon rests in the pools 

 between the periods of spawning activity and completes her task in from seven to ten 

 days. 



'The actual spawning act has seldom been observed, since it rarely occurs during the 

 daytime. The following description appears typical in as much as it agrees closely with 

 that of the spawning of the trout, particularly the rainbow. 



'The particular female salmon under observation was accompanied by two males, the 

 larger lying with its head two to three feet below the taU of the female and the smaller 

 some 6 feet below the first male and several feet to one side. Five minutes after several 

 hours of intermittent digging, the female lay extended at the upper part of the redd. 

 Without warning two males rushed quickly alongside, one on each side of the female. 



