TABLE 10. Frequency of association of completed Canada goose nests with 

 selected nest site parameters on the lower Yellowstone River, 1975 and 1976, 

 (The number of nests in each category is given in parentheses,) 



Percentage of nests constructed by a log 



Percentage of nests constructed on islands 



Percentage of nests constructed on peninsulas 



Percentage of nests constructed on fine substrate 3 



Number of additional nests b constructed in heron 



rookeries 

 Number of additional nests^ constructed on cliffs 



1975 



1976 



39.7 (29) 



95.9 (70) 



2.7 ( 2) 



97.3 (71) 



NOTE: Only significant percentages are included. No attempt was made in 

 this table to show, for example, components besides logs found around nests, 

 since only logs accounted for a significant percentage. 



a Substrate predominantly sand or silt composition 



Additional nests are those not surveyed because they were inaccessible 

 on foot. 



Clutch Sizes . Clutch size from goose nests within all study areas 

 averaged 5.3 and 5.6 eggs per clutch in 1975 and 1976, respectively. Similar 

 figures were reported from goose nests in other areas studied by Kossack (1950) 

 Hanson and Browning (1959), Martin (1964), Brakhage (1965), Hanson and 

 Eberhardt (1971) and Bowhay (1972). The frequency of clutch sizes encountered, 

 ranging from two to nine eggs per nest, is shown in figure 12. 



Nesting Success . The percentages of successful nests (those in which at 

 least one egg hatched) in 1975 and 1976 were approximately 65 and 50 percent, 

 respectively (table 5). Other researchers, including Steel et al . (1957), 

 Hanson and Browning (1959), Martin (1964), and Hook (1973), reported between 

 70 and 90 percent nest success. The loss of 50 percent or more of the nests 

 in at least one of the study sections on the lower Yellowstone was the result 

 of nest flooding in 1975 and nest desertion and predation in 1976. The high 

 number of nests lost to flooding in 1975 may represent nesting by inexperi- 

 enced two- or three-year-olds (Eng 1976). Late nesting by some pairs may have 

 increased the actual production and success rate in both years, but these late 

 nests were not surveyed in order to prevent any further nest loss or desertion. 



The high rate of nest predati 

 1976 compared with that observed i 

 difference in discharges during th 

 According to Koch (1976a), repairs 

 necessitated reduced outflow from 

 A comparison of the Yellowstone's 

 of 1975 and of 1976 shows this red 

 after the median date of nest init 

 was considerably lower than during 



on which occurred in some study areas in 

 n 1975 (table 5) may be related to the 

 e nesting season between these two years. 



on Yellowtail Dam in the spring of 1976 

 the dam during the first ten days of April, 

 discharge at Miles City during the springs 

 uction (figure 13). Shortly before and 

 iation in 1976, the discharge of the river 



the same period of the nesting season in 



35 



