the complete clutch size for 108 Mottled Duck nests in Texas ranged from 7 to 

 14 eggs, and averaged 10.4. 



Incubation Period Stieglitz and Wilson (1968) found that incubation of 

 eggs in the wild took 25-26 days; incubation was defined as the period from the 

 laying of the last egg to the emergence of the last duckling. Singleton (1953) 

 reported that Texas birds incubated from 25 to 27 days. 



Hatching Success In 1966 and 1967 at Merritt Island, 93.6% of the 612 eggs 

 in successful nests hatched (Stieglitz and Wilson 1968). However, 21 of 117 

 nests were not successful. Beckwith and Hosford (1957) reported that 15 of 16 

 eggs (94%) in two successful nests hatched, but 3 nests containing 21 eggs were 

 destroyed; thus, about 40% of the eggs laid hatched. Singleton (1953) reported 

 a hatching success of 96.2% for Mottled Ducks in Texas, but this may have been 

 only for successful nests. 



Fledging Success Data are not available. 



Age at Fledging Definite information is not available but Palmer (1976a) 

 estimated the age at first flight to be from 54 to 60 days. 



Age at First Breeding Mottled Ducks probably breed in their first year. 

 Weeks (1969) noted that in Louisiana, immature birds pair by mid-winter of their 

 first winter; nearly 90% of all ducks he observed during mid-winter were paired. 



Mortality of Eggs and Young Twenty-six of 78 (33%) nests that failed in 

 Texas were lost to predation by domestic dogs (Singleton 1953). Other major 

 sources of nest loss were human disturbances (15%) and burning (14%). 



Exceedingly little is known of the factors causing mortality in young birds. 

 Singleton (1953) saw but one instance of predation; in this instance a juvenile 

 was killed by a domestic dog. 



Renesting Singleton (1953) stated that the species is single-brooded and 

 reported an observation of one pair renesting five times before eggs were hatch- 

 ed; he also noted several instances of three nesting attempts. 



Maximum Natural Longevity An adult male banded in Texas was recovered in 

 the same state at a minimum age of 13 years, 5 months (Clapp et al. in press). 



Weight Beckwith and Hosford (1957) reported the mean weight of 30 adult 

 males as 1,030 g (2.27 lb); the mean weight of 11 adult females was 968 g 

 (2.13 lb). Maxima were 1,280 g (2.82 lb) for males, 1,131 g (2.49 lb) for fe- 

 males. 



SUSCEPTIBILITY TO OIL POLLUTION 



No reports of oiled birds are available. Oil washed into coastal marshes 

 by wave or wind action could affect nests or feeding grounds. 



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