Browsing by Subject "Extremely low frequency antenna systems"

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    ELF Communications System Ecological Monitoring Program: Bird Species and Communities Wisconsin Test Facility: Final Report
    (University of Minnesota Duluth, 1990) Hanowski, JoAnn M; Blake, John G.; Niemi, Gerald J; Collins, Patrick T
    This report summarizes work completed in our study that was designed to isolate effects of electromagnetic (EM) fields produced by extremely low frequency (ELF) antenna systems on bird species breeding in or migrating through Wisconsin. Specifically, we wanted to determine if bird species richness and abundance differed between areas that were close to the antenna and those that were far enough away to be unaffected by the antenna. Characteristics examined included total species richness and abundance, abundances of common bird species, and abundances of birds within selected guilds. Vegetation was measured to identify differences and similarities between control and treatment areas and habitat variables were used in analysis of covariance (ANCOVA) to compare abundant bird species’ numbers between control and treatment areas after they were adjusted for habitat differences. We found no consistent patterns that would demonstrate that birds were either attracted to or repelled by EM fields produced by the antenna. Most differences in abundance between control and treatment areas could be attributed to habitat differences (both in ANCOVA and guild analysis). Based on tests of transects paired by habitat similarities, the presence of the antenna ROW may have affected abundance of some bird species in the study areas. Abundance of species related to edges was higher in treatment areas particularly during May and June. Differences in abundance of individuals that require forest interiors between control and treatment areas were not as pronounced. Because we have no before data in Wisconsin, we cannot exclude the possibility that these differences between control and treatment existed before the ROW was cut, such comparisons, however will be possible in Michigan.
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    ELF Communications System Ecological Monitoring Program: Bird Species and Communities: Annual Report 1988-1989
    (University of Minnesota Duluth, 1989) Niemi, Gerald J; Hanowski, JoAnn M
    This investigation was designed to isolate effects of electromagnetic (EM) fields produced by extremely low frequency (ELF) antenna systems on bird species breeding in or migrating through Wisconsin and Michigan. Specifically, we seek to determine if bird species richness and abundance differ between areas that are close to the antenna and those that are far enough away to be unaffected by the antenna. We are pursuing this question at both the community and species level. Characteristics examined include total species richness and abundance, abundances of common bird species, and abundances of birds within selected guilds. Our monitoring program includes bird censuses over a five month period from May to September (1986-1989). Additional data were collected in June of 1985 and August-September of 1984. Here we summarize results of our 1989 research activities. The Michigan transmitter began 150 amp tuning and testing intermittently in the first part of May. On the 14th of May, the transmitter began continuous 150 amp operation for 16 hrs/day on weekdays and all day on weekends. On October 7th, the Michigan transmitter began full power continuous operation. We therefore consider May 1989 to be a transitional period, and June through September to be impact periods. Bird abundance and species diversity were highest in June and July in Michigan and in May and June in Wisconsin. No significant differences in community level parameters (total individuals, total species) were noted in either state. Considerable annual variation in numbers of individuals and species was noted. Particularly abundant species (all seasons included) included the Nashville Warbler, Ovenbird, White-throated Sparrow, Red-eyed Vireo, Black-capped Chickadee, Hermit Thrush and Golden-crowned Kinglet. The most abundant species present on treatment and control segments varied among seasons and between states. Among "abundant" species (>1 individual observed/500 m segment), five of 34 comparisons (over all seasons) revealed a significant difference between treatment and control XII segments in Michigan; four indicated a greater abundance on control segments. Six of 31 comparisons indicated a significant difference between treatment and control segments in Wisconsin; four indicated a greater abundance on control segments. Previous analyses of vegetation on Wisconsin and Michigan study sites (Blake et al. 1988) revealed differences between treatment and control plots. The difference most likely to influence bird populations was distribution of coniferous and deciduous habitats. Treatment segments supported more coniferous and lowland habitats than did control areas, in both states. To account for differences in habitat between treatment and control segments in Wisconsin, we paired treatment and control segments on the basis of habitat similarity and compared bird abundances on these paired segments (N = 15 pairs). (The Michigan study is designed as a "before-and-after" experiment and, thus, differences in habitat pose less of a problem for interpretation of bird distribution patterns.) Two of 31 comparisons of abundant species showed significant differences between paired segments in Wisconsin; in both cases, numbers were higher on treatment segments. The final report for Wisconsin will consider effects of vegetation on results from previous years and on distribution patterns of guilds. Eighteen of 105 comparisons of common species (based on prominence values) between treatment and control segments (all segments) in Michigan and 20 of 100 in Wisconsin were significant. Values were higher on control segments in Michigan in 9 cases; 6 of 20 were more abundant on control than on treatment segments in Wisconsin. Few species were consistently and significantly more abundant on either treatment or control segments among seasons within a year or within seasons between years. Differences between treatment and control segments are most likely due to habitat differences. Species were classified into guilds on the basis of foraging behavior and preferred breeding habitat. Few significant differences in abundances of birds within different guilds were found between treatment and control segments. Differences were most consistent for habitat categories, providing further evidence that habitat differences are responsible for many of the observed differences in bird distribution patterns between treatment and control segments.
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    ELF Communications System Ecological Monitoring Program: Bird Species and Communities: Annual Report 1989-1990
    (University of Minnesota Duluth, 1990) Blake, John G.; Niemi, Gerald J; Hanowski, JoAnn M; Collins, Patrick T
    This investigation was designed to isolate effects of electromagnetic (EM) fields produced by extremely low frequency (ELF) antenna systems on bird species breeding in or migrating through Wisconsin and Michigan. Specifically, we seek to determine if bird species richness and abundance differ between areas that are close to the antenna and those that are far enough away to be unaffected by the antenna. We are pursuing this question at both the community and species level. Characteristics examined include total species richness and abundance, abundances of common bird species, and abundances of birds within selected guilds. Our monitoring program has included bird censuses over a five month period from May to September (1986-1989). Additional data were collected in both states in August-September of 1984 and June of 1985. Research in Wisconsin was completed in 1989 but has continued in Michigan. A final report summarizing work in Wisconsin has been completed (Hanowski et al. in press). Here we summarize results of our 1990 research activities in Michigan. The Michigan transmitter began 150 amp tuning and testing intermittently in the first part of May 1989. On 14 May, the transmitter began continuous 150 amp operation for 16 hrs/day on weekdays and all day on weekends. On 7 October 1989, the Michigan transmitter began continuous operation at full power. We therefore consider 1990 to be the first full impact year. Overall, bird abundance and species diversity were highest and approximately the same during May, June, and July. Species diversity was significantly greater on control areas during June and September, but no other differences in community level parameters were significant. Considerable annual variation in numbers of individuals and species was noted. Particularly abundant species (all seasons included) included the Ovenbird, Black-capped Chickadee, and Nashville Warbler. Other common species included Red-eyed Vireo, White-throated Sparrow, Golden-crowned Kinglet, Hermit Thrush, and Black-throated Green Warbler. The most abundant species present on treatment and control segments varied among seasons. Among "abundant" species (>1 individual observed/500 m segment), five of 24 comparisons (21%; all seasons combined) revealed a significant difference between treatment and control segments in Michigan; two indicated a greater abundance on control segments. Previous analyses of vegetation on Michigan study sites (Blake et al. 1988) revealed differences between treatment and control plots. The difference most likely to influence bird populations was distribution of coniferous and deciduous habitats. Treatment segments supported more coniferous and lowland habitats than did control segments. It is important to note that habitat differences that exist between treatment and control areas will not affect our analysis of antenna effects. The Michigan study is designed as a before-and-after experiment; we can compare changes in bird abundance over time on treatment segments and on control segments. If electromagnetic fields produced by antenna operation affect bird distribution patterns, we expect to detect a change in patterns of abundance between treatment and control areas. Such changes, if they occur, would be independent of already present habitat differences. Seventeen of 114 comparisons (15%) of common species (based on prominence values, see page 7) between treatment and control segments (all segments) in Michigan were significant. Values were higher on control segments in 10 cases. Few species were consistently and significantly more abundant on either treatment or control segments among seasons within a year or within seasons among years. Differences between treatment and control segments were most likely due to habitat differences. Species were classified into guilds on the basis of foraging behavior and preferred breeding habitat. Few significant differences in abundance of birds within different guilds were found between treatment and control segments. Differences were most consistent for habitat categories (e.g., birds that prefer deciduous forest were more abundant on control segments in 4 of 5 months), providing further evidence that habitat differences were responsible for many of the observed differences in bird distribution patterns between treatment and control segments.
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    ELF Communications System Ecological Monitoring Program: Bird Species and Communities: Annual Report 1991
    (University of Minnesota Duluth, 1991) Blake, John G.; Niemi, Gerald J; Hanowski, JoAnn M; Collins, Patrick T
    This investigation was designed to isolate effects of electromagnetic (EM) fields produced by extremely low frequency (ELF) antenna systems on bird species breeding in or migrating through Wisconsin and Michigan. Specifically, we seek to determine if bird species richness and abundance differ between areas that are close to the antenna and those that are far enough away to be unaffected by the antenna. We are pursuing this question at both the community and species level. Characteristics examined include total species richness and abundance, abundances of common bird species, and abundances of birds within selected guilds. Our monitoring program has included bird censuses in both states over a five month period from May to September, 1986-1991. Additional data were collected in August-September 1984 and in June 1985, in both states. Bird censuses were terminated in Wisconsin after 1989 but are continuing in Michigan. No consistent patterns have yet emerged to demonstrate that birds are more or less abundant on treatment relative to control segments in either state after effects of habitat are accounted for. Further, few significant differences have been found at the community or species level; differences in one season or year are not always repeated in subsequent years or seasons. Most differences that exist between treatment and control transects can be attributed to habitat differences or chance rather than to electromagnetic field differences.
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    ELF Communications System Ecological Monitoring Program: Bird Species and Communities: Annual Report 1992
    (University of Minnesota Duluth, 1992) Helle, Pekka J.; Hanowski, JoAnn M; Niemi, Gerald J; Collins, Patrick T; Blake, John G.
    This investigation was designed to detect effects of electromagnetic (EM) fields produced by extremely low frequency (ELF) antenna systems on bird species breeding in or migrating through Wisconsin and Michigan. Specifically, we seek to determine if bird species richness and abundance differ between areas that are close to the antenna and those that are far enough away to be unaffected by the antenna. We are pursuing this question at both the community and species level. Characteristics examined include total species richness and abundance, abundances of common bird species, and abundances of birds within selected guilds. Our monitoring program has included bird censuses in both states over a five month period from May to September, from 1986 onwards. Additional data were collected in August-September 1984 and in June 1985, in both states. Bird censuses were terminated in Wisconsin after 1989 but are continuing in Michigan. No consistent patterns have yet emerged to demonstrate that birds are more or less abundant on treatment relative to control segments in either state after effects of habitat are accounted for. Further, few significant differences have been found at the community or species level; differences in one season or year are not always repeated in subsequent years or seasons. Most differences that exist between treatment and control transects can be attributed to habitat differences or chance rather than to electromagnetic field differences.
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    ELF Communications System Ecological Monitoring Program: Bird Species and Communities: Annual Report 1993
    (University of Minnesota Duluth, 1993) Hanowski, JoAnn M; Niemi, Gerald J; Blake, John G.
    This investigation was designed to detect effects of electromagnetic (EM) fields produced by extremely low frequency (ELF) antenna systems on bird species breeding in or migrating through Wisconsin and Michigan. Specifically, we seek to determine if bird species richness and abundance differ between areas that are close to the antenna and those that are far enough away to be unaffected by the antenna. We are pursuing this question at both the community and species level. Characteristics examined include total species richness and abundance, abundances of common bird species, and abundances of birds within selected guilds. Our monitoring program has included bird censuses in both states over a five month period from May to September, from 1986 onwards. Additional data were collected in August-September 1984 and in June 1985, in both states. Bird censuses were terminated in Wisconsin after 1989 but are continuing in Michigan. No consistent patterns are evident to demonstrate that changes in bird abundance differ between treatment relative to control segments in Michigan after the antenna became operational. No significant interactions found at the community or species level are always repeated in subsequent seasons. In addition, interactions in guild or individual species abundance patterns that exist between treatment and control areas in any season are not repeated in subsequent seasons. Number of significant interactions found at many levels of the analyses were not greater than the number expected by chance alone and are unlikely attributable to electromagnetic fields.
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    ELF Communications System Ecological Monitoring Program: Bird Species and Communities: Final Report 1994
    (University of Minnesota Duluth, 1994) Hanowski, JoAnn M; Niemi, Gerald J; Blake, John G.
    This investigation was designed to detect effects of electromagnetic (EM) fields produced by extremely low frequency (ELF) antenna systems on bird species breeding in or migrating through northern Wisconsin and northern Michigan. Specifically, we asked whether bird species richness and abundance differed between areas that were close to the antenna and those that were far enough away to be unaffected by EM fields produced by the antenna. We pursued this question at both the community and species level. Characteristics examined included total species richness and abundance, abundances of common bird species, and abundances of birds within selected guilds. Our monitoring program included bird censuses in both states over a five month period from May to September, from 1986 onwards. Additional data were collected in August-September 1984 and in June 1985, in both states. Bird censuses were terminated in Wisconsin after 1989 and in 1993 in Michigan. Final results were reported previously for the Wisconsin study. Interpretations of ELF EM field effects in the Michigan study reported here, were based on significance of the interaction term in a repeated measures analysis of variance. For this analysis we were not interested in whether bird abundance varied annually (year effect), but whether bird abundance varied over time in the same manner in treatment and reference study areas. No significant interactions found at the community, species, or guild levels were consistent in any season. The number of significant interactions found at many levels of the analyses were not greater than the number expected by chance alone and therefore were unlikely attributable to EM fields produced by the ELF antenna.