Females renested one or more times when the eggs were destroyed or 

 even when the ducklings disappeared on the first day after hatching. 

 At least eight out of 51 marked ducks were known to have renested. 



The dates of first laying ranged from March 9 to March 27. The 

 nesting peaks occurred about April 20. The first hatching occurred 

 in early April; the last in early August. The date by which 50 per- 

 cent of the nests were started was significantly earlier in 1953 than 

 in 1957 or 1958, but no other differences were significant. Comparison 

 of the peaks of hatching and of laying showed that in 1958 a loss of 

 early clutches occurred. 



Nests were built most extensively in woods, less so in fields and 

 marshes, and markedly less on duck blinds. They were constructed from 

 adjacent material (leaves, grass, twigs, pine needles) in shallow 

 basins, which were occasionally used by renesting females. Usually 

 the nest site was covered by honeysuckle, poison ivy, brush, or grasses. 

 Spacing between nests was determined by available cover; sometimes they 

 were placed within a few feet of each other. The density ranged from 

 0.6 to 15.2 nests per acre. 



The average number of eggs in a clutch declined from 10.9 to 7.5 

 during the season (360 clutches). Young females laid smaller average 

 clutches (9.2) than adults (9.7). Primary clutches were larger (9.1) 

 than secondary clutches (8.1) for the same females. The incubation 

 period averaged 26.2 days (51 clutches). Neither size of clutch nor 

 season had a significant effect on incubation period. About 5.6 

 percent of the eggs did not hatch. 



The fate of nesting was determined for 574 nests. During the six 

 years, 38.0 percent hatched at least one egg, 11.5 percent were 

 abandoned, and 50.0 percent were destroyed (34.0 percent by crows). 

 Although complete and incomplete clutches were equally susceptible 

 to predation, over half (51.8 percent) of the destruction of complete 

 clutches occurred in the first week of incubation. An average of 

 9.6 percent of eggs in successful clutches was taken by crows. 



Estimations of production indicated that 100 females would raise 

 510 young to flying age and that the population in the area would 

 decline if the mortality rate of females from flying age to breeding 

 exceeded 78 percent. (A. A.) 



Keywords: black duck, coastal marsh, nesting habits, productivity, 

 Maryl and 



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