Post-breeding activities of mallards and wood ducks in north-central Minnesota
We used radio telemetry to monitor the post-breeding activities of 129 mallards ( Anas platyrhynchos ) and 118 wood ducks ( Aix sponsa ) on a 932-km2 area in north-central Minnesota from 1968 to 1974. Upon completion of breeding activities and before the flightless period, all mallard drakes departed the area; this exodus peaked during early June. Of the non-brood hens 8 of 23 remained on the area, whereas 26 of 51 of the hens raising broods spent the flightless period on their breeding areas. Thirty-nine percent of the mallard hens on the area in the spring were present at the beginning of their flightless period. Fifty percent of the drake wood ducks and 41 percent of the hens left the breeding area before flightlessness. Their timing was similar to that of mallards. The flightless period began in mid-June for wood duck drakes and lasted into early October for some mallard hens. All late molting mallard and wood duck hens reared broods that same year. A minimum of 35 percent of the spring mallard hens remained on the area at the beginning of hunting season (early October). About 17 percent of the wood duck males and 42 percent of the females breeding locally remained on the area until hunting began. Eleven of 51 mallards and 4 of 25 wood ducks that reared broods were killed on the study area compared with 2 of 23 for non-brood mallards and 1 of 20 for non-brood wood duck hens. Principal habitats used by post-breeding mallards were bays of large lakes and river marshes. Wood ducks tended to use similar habitat but also frequented small woodland ponds. During the flightless period both species remained mostly in areas with abundant emergent cover.