NESTING CANADA GEESE IN HONEY LAKE VALLEY, CALIFORNIA 13 



Muskrats are heavily trapped in this area and permanent water is 

 scarce, so the number of muskrat houses is limited. All of the muskrat 

 houses were found within Type B. 



G. Canal Banks : This type was used commonly in the study 

 area. Nineteen nests or 11.2 per cent were found on canal banks in 

 1939, and 40 nests or 16.1 per cent in 1940. Although canal banks in 

 the study area had little cover, they are evidently preferred because 

 they afforded the desirable combination of elevation plus visibility. 



H. Willow : It was evident that the dense willow thickets that dot 

 the Honey Lake Valley landscape are not preferred nesting sites. No 

 nests were found in this type in 1939, but in April 1940, when high 

 water decreased the use of some of the other types, 5 nests or 2 per cent 

 of the total were found in willows. 



It is interesting to note that none of the nests located in this type 

 Avere successful. 



Fate of Nests 



In the course of the study the fate of 418 nests was determined. 

 Each nest was visited at intervals of not more than six days until its 

 fate was determined. The findings are shown graphically in Fig. 9. 



The writer recognizes the fact that the presence of an observer in 

 the field can, in itself, affect the rate of nesting success. His presence, 

 for instance, can cause an increase in the percentage of desertions. 

 The frequent flushing of birds from the nests and the trails left as a 

 result of his visits can cause an increase in predation losses. 



It is felt, however, that in the case of this study, the writer's activi- 

 ties had little effect on the total results. Persons other than the writer 

 were present in the area daily. In fact, many nests were reported by 

 ranchers who found them during the course of normal farming opera- 

 tions. Consequently, the writer's presence added but little to the 

 normal hazards associated with agricultural use. 



Successful Nests 



In 1939, 52.5 per cent of the nests were successful. In 1940, broods 

 were successfully hatched from 60 per cent. 



Successful nests were recognized by their appearance after the 

 eggs were hatched. In nearly all cases the shells of the hatched eggs 

 were crushed, presumably by the parent during the period that elapsed 

 between hatching and leaving the nest, Only bits of shell and the 

 crumpled inner shell membranes remained. In a few cases nests were 

 torn up by predators after the eggs had hatched out, but the character- 

 istic remains of hatched eggs were still present to indicate success. 



Unsuccessful Nests 



Desertion : In 1939, 11 or 6.5 per cent of the nests were deserted, 

 compared with 18 or 7.3 per cent in 1940. 



Of the 29 nests deserted during the two year period, 14 were 

 abandoned for unknown causes. Nine nests were deserted as the result 

 of .fighting among geese in areas where nests were placed close together. 

 In several instances an observer watched ganders fighting over nesting 



