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Mallard Recruitment in the Agricultural Environment of North Dakota

Cause of Nest Loss


Predation was by far the most important cause of nest failure. It accounted for nearly 70% of the unsuccessful nests and probably was a factor in loss of nests to abandonment and unknown causes (Table 11). Abandoned nests frequently had eggs disappear between the first and second visits. Klett and Johnson (1982) suggested that Franklin's ground squirrel (Spermophilus franklinii) may have been responsible for egg loss. Perhaps disturbance by ground squirrels also causes abandonment. Other abandoned nests were uncovered, which suggests that the hen may have been flushed by a predator thus causing her to abandon the nest. If the hen was never seen after abandonment, she may have been killed and removed from the nest. We were unable to determine the cause of loss of 8 nests, either because it was not possible to distinguish among predation, weather, and machine destruction or we were unable to relocate the nest even though we knew it was unsuccessful from telemetry data. We were unable to identify the predator responsible for nest destruction in 77% of the predator-destroyed nests examined. Even for those nests where the appearance of the nest and shell fragments closely resembled published descriptions (Rearden 1951, Einarsen 1956), we felt that the evidence was not conclusive. We relied on strong circumstantial evidence such as observation of the predator or its tracks or recovery of the hen from a den.

Table 11. Fate of 129 nests of radio equipped mallard hens in central North Dakota.
Class Year
1977 1978 1979 1980 All years
N %a
Successful 3 11 8 8 30 23.3
Unsuccessful 14 23 29 33 99 76.7
Abandoned 0 1 7 3 11 11.1
Predator destruction 11 19 15 24 69 69.7
Skunk 1 2 1 3 7 10.1
Raccoon 1 0 0 1 2 2.9
Ground squirrel 1 0 0 0 1 1.4
Fox 1 1 2 1 5 7.2
Mustelid 0 0 0 1 1 1.4
Unknown predator 7 16 12 18 53 76.8
Other destruction 3 3 7 6 19 19.2
Machine 2 2 2 2 8 42.2
Livestock 1 1 0 0 2 10.5
Weather 0 0 0 1 1 5.3
Unknown 0 0 5 3 8 42.2
Totalb 17 34 37 41 129 100.0
aShown as percent of subcategory.
bDoes not include nests where observer caused abandonment or nests where the fate   was unknown.

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