DEEP: Dry Conditions Prevail for Breeding Waterfowl Survey

Dry Conditions Prevail for Breeding Waterfowl Survey
Adapted from an article that appeared in the July/August 2002 issue of  Connecticut Wildlife.

{Wood duck perched on nest box.}
An estimated 4,172 pairs of wood ducks were observed during the 2002 breeding waterfowl survey.

The dry conditions that had persisted in Connecticut were all too evident when the breeding waterfowl survey was conducted this past spring. Since its inception in 1989, the states from Virginia north to New Hampshire have participated in this important survey. The survey is ground-based and targets randomly placed square kilometer plots. In the northern states and Canada, breeding waterfowl surveys are conducted from the air along fixed transects. The spring breeding waterfowl survey provides part of the data that drives the Eastern Mallard Adaptive Harvest Management (AHM) models. Outputs from these models determine the lengths and bag limits of duck hunting seasons in the Atlantic Flyway. As the black duck and Canada goose AHM processes become formalized, the data derived from these surveys will be used in those models as well. Additionally, the breeding survey provides wildlife managers with an index to both habitat condition and waterfowl production.

The 2002 surveys in Connecticut indicated that habitat conditions were relatively poor this year. Most of the non-urban survey plots had scant amounts of water, 9% being completely dry. Coastal habitats, although not as affected by lack of rainfall as inland sites, were also fairly dry this spring. Salt marsh restoration work being conducted along the coast has helped to mitigate some of the problems that dry weather poses for wildlife nesting in the coastal marshes.

As is typical, mallards and Canada geese dominated the survey. Mallard breeding pair estimates were 20,244. This is a 25% increase from 2001 and a 33% increase from the five-year average. Canada goose pair estimates were 10,456. This represents a 28% decline from 2001 and a 16% decline from the five-year average. Both the wood duck and black duck estimates were down from 2001 and their respective five-year averages. Wood ducks were estimated at 4,172, nearly 45% of last year’s estimate and 26% below the five-year average. Black ducks were not observed inland and the coastal estimate was 114 pairs. This is half of last year’s estimate and 80% below the five-year average. Mute swans, a deleterious and introduced species, were observed in 14% of the plots this year. Eighty-five percent of mute swan occurrences were in inland survey plots. Rare Connecticut breeding species, such as gadwall and blue-winged teal, were also observed during the survey. The hooded merganser, a cavity-nester similar to the wood duck, seems to be gaining a foothold in the state, and the survey indicated an estimated 346 breeding pairs.
Since the beginning of the survey in 1989, there has been annual variation in all species breeding pair estimates, but particularly with black duck and wood duck counts. Some of the year-to-year estimates of these two species differ by over 400%. These changes in estimated breeding pairs do not correlate with harvest estimates, thus are likely the result of bias. Much of this variation is likely attributable to bias introduced by different observers from year to year, changing habitat conditions and the secretive nature of wood ducks and black ducks relative to mallards and Canada geese. Both mallards and Canada geese will readily use park ponds, backyard ponds and large lakes; all highly conspicuous areas. Black ducks and wood ducks typically use more forested wetlands for breeding. Ground surveys can be difficult to conduct in these habitats and less conspicuous species which use habitat characterized by thick cover can easily be overlooked.

In order to assess some of this variation, 30% of the inland plots and all of the coastal plots were surveyed from the air immediately after the ground surveys were completed. Aerial survey results differed significantly from ground survey results in both number of birds observed, and in some cases, species observed. The Wildlife Division will continue to assess the efficacy of aerial surveys for part or all of Connecticut’s breeding waterfowl plots.

Breeding waterfowl and all species dependent upon healthy wetland systems face an increasingly uphill battle in Connecticut. Wetland loss, the effects of exotic species invasions and the overall degradation of our wetlands have and continue to result in a gradual decline in both species abundance and diversity. The continued acquisition, conservation and enhancement of Connecticut’s remaining fresh and saltwater wetlands is of paramount importance to the future biodiversity of this state.