Incubation Rhythms of Ring-Necked Ducks

Abstract

Incubation behavior of Ring-necked Ducks (Aythya collaris) was studied in northwestern Minnesota from 1978 to 1980. Incubation constancy was similar for all birds (85%), but recess duration and frequency differed for females nesting along cattail/open water edges (X = 47 min, 5.1 recesses/day) and in flooded sedge meadow (x = 73 min, 2.7 recesses/day) away from open-water feeding areas. Timing of recesses also was influenced by nest site location. Nest attentiveness of Ring-necked Ducks apparently is influenced by nutrient reserve levels in females at the onset of incubation and food availability in wetlands used by breeding birds. My findings are consistent with Afton's (1979, 1980) prediction that in smaller species, environmental factors increasingly affect anatid incubation rhythms, and they generally support his conclusion that the relationship of fasting endurance to body size has been very important in the evolution of avian incubation behavior.