Macroinvertebrate abundance, water chemistry, and wetland characteristics affect use of wetlands by avian species in Maine

Abstract

Our objective was to determine use by avian species (e.g., piscivores, marsh birds, waterfowl, selected passerines) of 29 wetlands in areas with low (<200 leq l )1 ) acid-neutralizing capacity (ANC) in southeastern Maine. We documented bird, pair, and brood use during 1982-1984 and in 1982 we sampled 10 wetlands with a sweep net to collect invertebrates. We related mean numbers of invertebrates per wetland to water chemistry, basin characteristics, and avian use of different wetland types. Shallow, beaver (Castor canadensis)-created wetlands with the highest phosphorus levels and abundant and varied macrophyte assemblages supported greater densities of macroinvertebrates and numbers of duck broods (88.3% of all broods) in contrast to deep, glacial type wetlands with sparse vegetation and lower invertebrate densities that supported fewer broods (11.7%). Low pH may have affected some acid-intolerant invertebrate taxa (i.e., Ephemeroptera), but high mean numbers of Insecta per wetland were recorded from wetlands with a pH of 5.51. Other Classes and Orders of invertebrates were more abundant on wetlands with pH > 5.51. All years combined use of wetlands by broods was greater on wetlands with pH £ 5.51 (77.4%) in contract to wetlands with pH>5.51 that supported 21.8% of the broods. High mean brood density was associated with mean number of Insecta per wetland. For lentic wetlands created by beaver, those habitats contained vegetative structure and nutrients necessary to provide cover to support invertebrate populations that are prey of omnivore and insectivore species. The fishless status of a few wetlands may have affected use by some waterfowl species and obligate piscivores.

Influence of fish assemblage and shallow lake productivity on waterfowl communities in the Boreal Transition Zone of western Canada

“…Increased waterfowl density along a productivity gradient has been well documented in studies that consider lakes over a broad range from oligotrophic to hypereutrophic conditions (Hoyer & Canfield, 1994;Longcore et al, 2006). Our results indicate that this relationship also holds in the more limited eutrophic to hypereutrophic range.…”

Wetland Use and Selection by Breeding Waterbirds in the Boreal Forest of Quebec, Canada

“…In other forested regions of North America, beaver ponds have been recognized as important waterfowl breeding habitats, because they are used by all dabbling ducks, wood duck, hooded merganser, and ring-necked duck (Renouf 1972;Brown and Parsons 1979;Brown et al 1996;McCall et al 1996;Rempel et al 1997;Longcore et al 2006). This species assemblage would fit our results perfectly if we rely on flooded swamps as indicators of beaver ponds.…”

“…Smaller wetland size reduces exposure to wind and wave action (Cowardin et al 1979). Influence of beaver, presence of macrophytes (Longcore et al 2006), and absence of fish (Mallory et al 1994;Marklund et al 2002), which are conditions most likely to be found in wetlands of limited extent, are other positive factors that may also contribute in explaining the importance of small wetlands for nonpiscivorous waterfowl species. Studies of habitat use and selection by breeding waterfowl often relate pair distribution to pond or lake descriptors, leaving stream habitats unaddressed (e.g.…”

“…This is the case for waterbird populations that breed in forested landscapes of Quebec, forests that cover an area of more than 500,000 km 2 and support over 355,000 breeding pairs of ducks, geese and loons (Bordage et al 2003). The vast forest landscapes of Quebec nevertheless harbor the core of the breeding ranges of the American black duck (Anas rubripes) (Longcore et al 2000) and the eastern North American population of Barrow's goldeneye (Robert et al 2000), a population currently designated as being of special concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC 2007). Overall, 18 species of waterfowl and the common loon (Gavia immer) breed regularly in Quebec forests.…”

The effects of a colony of the Armenian gull (Larus armeniacus Buturlin) on zooplankton in the Lake Sevan littoral zone (Armenia)

“…In addition to removal of a part of the lake's biolog ical resources, the birds provide an input of large amounts of organic and mineral compounds that potentially affect the development of aquatic animals [24,25,27]. Studies of the Lake Sevan littoral areas in July 2007 revealed noticeable differences in the planktic community near the gull colony compared to commu nities that are situated far from the nesting colony [8].…”