Effect of Sewage Effluent on Bird Abundance and Species Composition in a Northern Minnesota Wetland

Bird abundance was monitored before (1985 and 1987) and after (1989) sewage wastewater effluent was added to a northern Minnesota wetland. Community parameters (i.e., number of individuals and species richness) varied annually, but, overall bird communities in 1985 and 1989 were more similar to each other than they were to the 1987 community. Relative abundance of 35 bird species was unchanged between years and species abundance ranks were not different between years. Distribution of numbers of individuals (relative percent) within nesting and foraging guilds (species that have similar nesting or feeding requirements) was similar among years. Numbers of species that increased or decreased between years was independent of nesting or foraging location (e.g., ground or above ground). Overall, no differences were detected in the bird community that could be attributed to addition of sewage effluent to the wetland up to two years after treatment (1987 to 1989)

Breeding Bird Populations in a Proposed Wetland Treatment Area of Northern Minnesota

A census of breeding bird populations was taken in a 40- hectare wetland near Biwabik, Minnesota, prior to the use of this wetland for phosphorus removal from treated wastewater. The wetland was comprised of four distinct habitat types: shrub swamp, black ash (Fraxinus nigra) forest, open coniferous forest, and closed coniferous forest. We used a line transect (about 4 km in length) to document species composition, relative species abundance, and habitat associations of the bird community. A total of816 individuals (mean= 204) and 45 species (mean = 34) were observed during four censuses in June and July, 1985. Two distinct bird communities were present in this wetland: those associated with ombrotrophic habitats (shrub swamp and ash forest) and those present in mincrotrophic habitats (open and closed coniferous forest). The Nashville warbler ( Vermivora ruficapilla) was the most common species in the wetland and also the only species that occurred in both minerotrophic and ombrotrophic habitats. The pre-impact data collected will allow assessment of the relative impact of adding sewage effluent to this wetland and the subsequent effect on bird species and populations

Effects of Two (Diptera: Culicidae) Mosquito Control Agents on Growth and Reproduction of Red-Winged Blackbirds (Agelaius phoeniceus)

We compared red-winged blackbird (Agelaius phoeniceus) reproductive success and nestling growth in 1988 in 10 wetland site treated with methoprene and 10 sites treated with Bacillus thuringiensis israelensis (Bti) to 30 sites that had never received any mosquito (Diptera: culicidae) control treatment. No differences were detected between reference and treatment sites for clutch size, egg volume, growth rates, or fledge weight. The probability that an egg survived to the nestling stage was greater in methoprene-treated than reference sites. No other differences were detected among sites for reproductive success estimated using the Mayfield method. We conclude that treatment of the wetlands with methoprene or Bti did not directly or indirectly affect red-winged blackbird growth or reproduction within the first two years after treatment

Breeding Bird Communities Across an Upland Disturbance Gradient in the Western Lake Superior Region

The coastal region of western Lake Superior to examine relationships to human land use. Eighty-four species were detected and 50 were abundant enough to be included in data analysis. Monotonic quadratic regression models were constructed for these 50 species by using species counts as the dependent variable and the proportion of human conversion of the landscape (residential, agriculture, and commercial/industrial land uses) within each study area as the independent variable. Twenty-seven bird species had significant regressions (P < 0.05), 18 of which generally avoided areas developed by humans and 9 of which were attracted to development. De-trended correspondence analysis using counts of these 27 bird species was used to investigate multivariate, community responses to development. The first DCA axis was interpreted as a gradient from urban avoiding to urban exploiting bird species and was strongly correlated with land cover variables related to human development. Our results advance the idea that breeding bird communities can be used as indicators of ecological condition and can diagnose potential causes for changes in these conditions. Further, our study points out the usefulness of bird monitoring data in regional planning efforts that incorporate goals for maintaining native biological diversity

Environmental Indicators for the Coastal Region of the U.S. Great Lakes

The goal of this research collaboration was to develop indicators that both estimate environmental condition and suggest plausible causes of ecosystem degradation in the coastal region of the U.S. Great Lakes. The collaboration consisted of 8 broad components, each of which generated different types of environmental responses and characteristics of the coastal region. These indicators included biotic communities of amphibians, birds, diatoms, fish, macroinvertebrates, and wetland plants as well as indicators of polycyclic aromatic hydrocarbon (PAH) photo-induced toxicity and landscape characterization. These components are summarized below and discussed in more detailed in 5 separate reports (Section II). Stress gradients within the U.S. Great Lakes coastal region were defined from 207 variables (e.g., agriculture, atmospheric deposition, land use/land cover, human populations, point source pollution, and shoreline modification) from 19 different data sources that were publicly available for the coastal region. Biotic communities along these gradients were sampled with a stratified, random design among representative ecosystems within the coastal zone. To achieve the sampling across this massive area, the coastal region was subdivided into 2 major ecological provinces and further subdivided into 762 segment sheds. Stress gradients were defined for the major categories of human-induced disturbance in the coastal region and an overall stress index was calculated which represented a combination of all the stress gradients. Investigators of this collaboration have had extensive interactions with the Great Lakes community. For instance, the Lake Erie Lakewide Area Management Plan (LAMP) has adopted many of the stressor measures as integral indicators of the condition of watersheds tributary to Lake Erie. Furthermore, the conceptual approach and applications for development of a generalized stressor gradient have been incorporated into a document defining the tiered aquatic life criteria for defining biological integrity of the nation’s waters. A total of 14 indicators of the U.S. Great Lakes coastal region are presented for potential application. Each indicator is summarized with respect to its use, methodology, spatial context, and diagnosis capability. In general, the results indicate that stress related to agricultural activity and human population density/development had the largest impacts on the biotic community indicators. In contrast, the photoinduced PAH indicator was primarily related to industrial activity in the U.S. Great Lakes, and over half of the sites sampled were potentially at risk of PAH toxicity to larval fish. One of the indicators developed for land use/land change was developed from Landsat imagery for the entire U.S. Great Lakes basin and for the period from 1992 to 2001. This indicator quantified the extensive conversions of both agricultural and forest land to residential area that has occurred during a short 9 year period. Considerable variation in the responses were manifest at different spatial scales and many at surprisingly large scales. Significant advances were made with respect to development of methods for identifying and testing environmental indicators. In addition, many indicators and concepts developed from this project are being incorporated into management plans and U.S. 8 EPA methods documents. Further details, downloadable documents, and updates on these indicators can be found at the GLEI website - http://glei.nrri.umn.edu

Natural Resources Research Institute Technical Report

We continued to collect baseline data on the large plantations that have been established in the Alexandria area. Three sites have been surveyed for four years, six sites for three years, and four sites f.or two years. We observed a linear growth in mean numbers of individuals and species on plantations as they have aged from one to six years. Species diversity has plateaued after five years on two sites. Plantations that had partial tree failure in previous years had greater species diversity. This was expected because these sites have two or three ages of trees present on the site and were more heterogeneous in the bird habitat they provided. Species turnover rates were 57% for plantations that aged from one to two years and were 53% for plantations that aged from two to three years. The largest proportion of bird individuals in plantations in the first six years were short-distance migrants. Numbers of individuals that migrate long-distances to Central and South America increased slightly as the plantations aged. Very few permanent resident birds were found in plantations at any age. Most individuals observed in the plantations at all ages were ground feeding birds associated with open field and pasture habitats. Very few foliage gleaners individuals and those associated with forested habitats were observed in the plantations at any age. Numbers of shrub birds and those that eat seeds increased as the plantations have grown. Studies were again (repeated from 1995) conducted on predation rates of artificial bird nest~ to test the hypothesis that predation rates in forests and grasslands adjacent to plantations are not affected by distance to the edge of the plantation. Data collected on predation rates this past summer support the alternative hypothesis that predation rates are independent of habitat type and distance from edge of plantation. We found that predations rates were site specific and were likely affected by local predator populations. These results support conclusions made from similar studies collected in 1995. The geographic information system (GIS) that included land cover types within a 2-3 mile radius of each plantation in the Alexandria area (for details see small mammal report) was completed. Canonical correspondence analyses (CANOCO) on the plantations established after or during 1994 indicated that the landscape surrounding many plantations was similar and was dominated by cropland. Exceptions to this were the Kreyer and Nelson sites which had .more water, woodland, and pasture (Kreyer) and wet and dry wildland (Nelson) in the surrounding landscape. Bird species such as the Sedge Wren, Mallard, Common Yellowthroat, Ring-necked Pheasant, Blue-winged Teal found within the Nelson site relected the presence of the adjacent wet and dry wildland habitat. The Chipping Sparrow, Eastern Bluebird, Grasshopper Sparrow and Vesper Sparrow found in the Kreyer site reflected the composition of the surrounding forest and pasture habitat