Characteristics of some black duck nest sites in Maine

A standard method for characterizing nest sites and concealment (visibility of orange decoy and percent overhead cover measured by densiometer) was used to obtain characteristics of 36 nest sites of black ducks in Maine, 1978-89. Nest locations were represented by cutover areas (10), islands (6), bogmat (5), emergent meadow (5), emergent wetland (3), stream floodplain (3), hardwood forest (1), conifer forest (1), mixed forest (1) and ephemeral pond (1). Within these locations nests were found in shrub clumps (1), under conifers (6), on hummocks (6), on ericaceous mats (4), under a clump of hardwood trees (4), under woody slash (3), on an emergent herbaceous clump (1), on a boulder (1) and on a muskrat house (1). After excluding 7 nests disturbed by investigators, 22 (76%) of the 29 remaining nests were successful nests. Nests in upland cuts were especially successful (9 of 9) and success was 75 - 100% at most locations, but both nests along stream floodplain were abandoned because of human disturbance. Unsuccessful nests were usually closer to ponds (2.5 times) or streams (6.6 times) and often at land water interfaces, i.e., islands and bogmat. Nests under conifers (5 of 6) and woody slash (3 of 3) usually were successful. The combination of low nesting density and isolation of nests in upland cutover areas (successful nests averaged nearly 3 times farther from roads) seem to influence black duck nest success.