Document Type

Conference Paper

Publication Date

1991

Publication Title

Proceedings of the Back Bay Ecological Symposium

Pages

167-182

Conference Name

Back Bay Ecological Symposium

Abstract

Coastal southeastern Virginia and northeastern North Carolina are considered to be within the primary breeding and wintering range of the Wood duck (Aix sponsa). To restore and expand the local Wood duck population, Mackay Island National Wildlife Refuge introduced 37 pairs of pen-reared Wood ducks in 1970. Concurrently, 34 nest boxes were erected on the refuge. The total number of nesting boxes has expanded at a moderate pace to where the number of boxes now totals 121. The nest box program during all or part of the 10 year period from 1980 - 1989 was evaluated to: (1) assess general nesting success, (2) determine the extent of nest parasitism by European starlings (Sturnus vulgaris), (3) measure habitat preference, and (4) identify whether nest box checks made during the spring versus the winter affected accuracy/reliability of nesting data. The accumulative mean rate of nesting success for 1980 - 1989 was estimated to be 81 percent, while the rate of box use or nest starts for the same period was 77 percent. Between 1983 and 1987, starling use of nest boxes grew from 18 to 54 boxes (200 percent). The corresponding mean rate of success for all nesting boxes with starling use declined from approximately 75 percent in 1983 to below 30 percent in 1989. The mean hatching rate parallelled this decline. Commencing in 1987, a modified nest box design that permitted greater light penetration into the cavity was utilized for all box replacements and additions. The rate of starling use in the modified nest box was 20 percent less overall than that for the standard nest box design. Generally, no distinguishable preference was evident between nest boxes placed in open marsh, wooded/semi-enclosed, and marsh-wood edge habitats. When nest box designs were segregated by habitat type, the proportionate rate of starling use was greatest for those standard boxes in open marsh habitats.

Wood duck nest box inspections occurred during both spring/summer and winter seasons from 1980-1989. The relative reliability of winter checks was determined to be equivalent to spring/summer inspections when the spring/summer data of 1980-1982 were compared to the winter records from 1983-1989. Black rat snakes (Elaphe obsoleta) were determined to be the principal nest predator. It is unlikely that the season of inspection will influence the reliability of the production estimate unless nest box predator populations undergo significant fluctuation.

The data confirms the growth and fidelity of the Wood duck population on the refuge. Despite an inhibition by Wood ducks to pioneer into new territory, the data suggests that the Back Bay, North Landing River, and Currituck Sound watersheds have the nucleus of a breeding population, at the very least. The judicious selection, placement, and maintenance of nesting boxes, within these integrated watersheds, affords an opportunity to expand the breeding population.

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