Browsing by Author "Lima, Ann R"
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Item Bird Population Trends in Minnesota and Northwestern Wisconsin Forests, 1991-1997(University of Minnesota Duluth, 1998) Hawrot, Rita Y; Hanowski, JoAnn M; Lima, Ann R; Niemi, Gerald J; Pfannmuller, LeeThe status of forest birds has been the subject of considerable interest (Terborgh 1989). Longterm monitoring can be used to identify species at risk by providing information on abundance patterns. We previously summarized our results on bird population trends in the Chippewa and Superior National Forests (NF), Minnesota, after three years of monitoring (Hanowski and Niemi 1994). In both forests, the Gray Jay, Winter Wren, Nashville Warbler, and American Redstart increased significantly and the White-throated Sparrow and Red-eyed Vireo decreased significantly. We also looked at population trends of breeding birds in Minnesota and Minnesota forested regions over the past 28 years using data from the North American Breeding Bird Survey (BBS), a continental monitoring program which uses roadside counts to sample breeding birds (Sauer et al. 1997) (Niemi et al. 1995). Forty-two percent of species (49 species) examined had no significant change in abundance,'36% (42 species) had significant increases, and 21% (25 species) had significant declines. Most species with declining trends could be grouped into three broad categories: species associated with forests, species of agricultural landscapes, and species associated with wetlands. In 1997, we completed the seventh year of our forest breeding bird monitoring program. Since the program’s initiation in 1991, we have added three study areas: the Chequamegon NF of northwestern and central Wisconsin, and Minnesota’s St. Croix River Valley (St. Croix) in 1992; and southeastern Minnesota (Southeast) in 1995 (Figure 1). Northern Minnesota and northwestern Wisconsin are located in the southern boreal-northern hardwood forest border (Pastor and Mladenoff 1991). Much of the conifer forest has been converted to aspen and birch since the middle of the last century (Coffin and Pfannmuller 1988). The present landscape has fewer conifer stands and more deciduous stands such as aspen and birch (Green 1995). Southeast Minnesota and central Wisconsin (southern most extent of the Chequamegon NF) are part of the eastern deciduous forest. Forests in this region have been altered by agricultural development or urban growth (Coffin and Pfannmuller 1988). We are currently monitoring five study areas by conducting over 1600 habitat-specific point counts each breeding season (Howe et al. 1997). Our objectives are to (1) identify species that have significant population trends for each study area; (2) identify species with significant population trends over the region; and (3) compare our results to trends from Minnesota BBS.Item Breeding bird monitoring in Great Lakes National Forests: 1991-1998(University of Minnesota Duluth, 1999) Hanowski, JoAnn M; Niemi, Gerald J; Hawrot, Rita Y; Lima, Ann RA total of 133, 162, and 128 stands (1,269 census points) were surveyed in the Chippewa, Superior and Chequamegon National Forests, respectively. Surveys have been completed for 8 years in the Chippewa and Superior and for 7 years in the Chequamegon. One-hundred seventy census points were surveyed in East Central Minnesota over the past 7 years and 211 census points in Southeast Minnesota over the past 4 years. A total of 74 species were abundant enough in at least one region to test for trends in annual abundance. Fifty species in the Chippewa National Forest, 45 species in the Superior National Forest, 50 species in the Chequamegon National Forest, 32 species in East Central Minnesota, and 38 species in Southeast Minnesota were tested. The average number of species and individuals observed/stand or point in four of five study regions were at an all time high in 1998. In contrast, the lowest number of species and the second lowest numbers of individuals were observed in Southeast Minnesota in 1998 than in the previous three years. A In the Southeast Minnesota region 57% of the species tested showed a significant trend in abundance. In the other four regions, 84 to 98% of the species tested exhibited a significant trend in abundance. Almost 30% of the species in Southeast Minnesota showed significant linear decreasing trends from 1995 through 1998 and an additional 19% had negative overall trends. Ten percent of the species in Southeast Minnesota had increasing abundance trends. In contrast, in the other four regions more than 63% (63 to 74%) of the species have increased in abundance from 1991 (or 1992) to 1998. The percent of the species that have declined in the other regions ranged from 25% in the Superior National Forest to 12% in the Chippewa National Forest. A total of 38 species showed significant decreases (linear or other) in at least one region. Of these, 22 species (59%) also increased significantly in another region. Fifteen species decreased in one or more regions without indicating increases in other regions. Ten species declined in one region and six species, the Downy Woodpecker, Golden-crowned Kinglet, Gray Catbird, Canada Warbler, Indigo Bunting and American Goldfinch declined in two regions. About 64% (7 of 11) of the permanent residents tested showed a significant decrease in one region. The proportion of short distant migrants that declined was about 40% (9 of 22) of the total number tested and about 55% (22 of 40) of the long distant migrants tested decreased in abundance in one region. When species were categorized by nest location, the largest proportion of species decreasing were cavity and canopy nesting species. The proportion (all about 50%) of species declining within general habitat groups was almost equal across open, young forest, and forest habitat groups. The spring of 1998 was affected by the El Nino weather pattern and was warmer than average in all regions. Precipitation was lower in April than normal, but wetter than normal in the other spring months. June in all regions was cooler and wetter than normal. The warm spring in the Great Lake’s area affected: 1) timing of permanent resident breeding which was earlier than normal, and 2) timing of short distance migrant arrival which was also earlier than normal. Arrival times of long distance migrants were not affected by local weather patterns. We speculate that breeding of long distance migrants was also somewhat earlier in 1998. This is supported by the observations of more than the average number of fledglings during our late-June and early July survey dates. It is also likely that more double brooding occurred in 1998 due to the favorable weather conditions, although we have no data to support this hypothesis. Another potential reason for an increase in numbers of individuals in 1998 is also related to the warm spring weather and the theory of heterospecific attraction. Our data support this hypothesis: number of breeding migrants over the eight years of monitoring was highly correlated (r=0.701 and p< 0.001) with the number of foliage and bark gleaning insectivorous permanent residents. Specifically, in years where we observed the greatest numbers of Black-capped Chickadees, Red- and White-breasted Nuthatches and Blue Jays we also recorded the largest number of migrant individuals. Four of the six species that decreased in abundance in more than one region (Gray Catbird, Canada Warbler, Indigo Bunting and American Goldfinch) are associated with early successional, edge, or shrub habitat. Of the other two species that declined, the Downy Woodpecker occurs predominantly in mature deciduous forests and the Golden-crowned Kinglet is most abundant in mature lowland conifer habitat. It is difficult to determine the exact cause of these species declines. However, more detailed studies may be required for these species if declines continue.Item Effects of Disturbance of Water-Quality Functions of Wetlands(University of Minnesota Duluth, 1991) Johnston, Carol A; Detenbeck, Naomi E; Hagley, Cynthia; Taylor, Debra A; Lima, Ann R; Bamford, StaceyThe following report has been organized into three sections. The first two sections represent rough drafts of manuscripts on 'Temporal and spatial variability of wetland water- quality in The Minneapolis/St. Paul area" and "Effects of physical, chemical, and hydrologic disturbance on wetland water-quality". The third section summarizes work in progress on assessing time trends in wetland water quality function.Item Evaluation of the potential effects of methoprene and BTI (Bacillus thurinqiensis israelensis) on wetland birds and invertebrates in Wright County, MN, 1988 to 1993(University of Minnesota Duluth, 1995) Niemi, Gerald J; Axler, Richard P; Hanowski, JoAnn M; Hershey, Anne E; Lima, Ann R; Regal, Ronald R; Shannon, Lyle JThis report summarizes the results of a six year study (1988 to 1993) to assess the potential effects of two mosquito control materials, methoprene (applied as Altosid sand granules) and Bacillus thuringiensis var. israelensis (Bti, applied as Vectobac-G granules) on zooplankton, aquatic insects, and breeding birds in the Twin Cities metropolitan area. The study was a before-and-after design with 1988 to 1990 as pre-treatment and 1991 to 1993 as treatment years. A total of 27 wetlands in western Wright County were randomly selected and randomly placed within one of three groups of sites: 9 control, 9 Bti-treated, and 9 methoprene-treated. Selected populations of zooplankton, aquatic insects, and breeding birds were sampled within each of these wetlands. Each site was also monitored to verify the applications of Bti or methoprene to the respective sites and to verify that the control sites were not treated. In 1992, the number of study sites was reduced to 26 because of the loss of one methoprene-treated site from sampling. No effects could be attributed to treatment on zooplankton or breeding birds. Aquatic insects, however, were considerably reduced following treatments in 1992 and 1993. Chironomids comprised approximately 60% of the total individuals sampled, and were greatly reduced in both methoprene and Bti sites compared to controls. We focused on this group particularly because of their abundance, but also because they are closely related to mosquitoes and known to be susceptible to both larvicides. However, our results showed that all insect groups were similarly affected by both larvicides. Both Bti and methoprene applications to these wetlands reduced aquatic insect densities by a range of 57-83% and biomass by a range of 50-83% in the second and third years of treatment. Following the effects of treatments observed in 1992, populations of aquatic insects recovered to pre-treatment levels at the start of 1993, but quickly declined again following treatment. No food chain effects of these declines, with the possible exception of increases in the density of some copepods in methoprene-treated sites, were observed in either zooplankton or in breeding birds. High nest loss rates due to predation may have been a greater limiting factor to birds than mosquito control treatment. The carrying capacity of bird populations may also be lower than that affected by food reductions, especially since alternative foods tended to be available for Red-winged Blackbirds outside of the wetland study sites. Even though this study represents one of the largest ever conducted to assess the effects of mosquito control materials on non-target organisms, a variety of questions regarding the overall effects of mosquito control treatments remain unanswered. Among the most pressing questions are the determination of the long term effects (e.g., > 5-10 yrs) of the control program and whether populations of aquatic insects can continue to recover within these treated areas.Item Monitoring Bird Populations on National Forest Lands: 1994(University of Minnesota Duluth, 1994) Hawrot, Rita Y; Hanowski, JoAnn M; Niemi, Gerald J; Lima, Ann RA habitat specific bird monitoring program was established on the Chequamegon, Chippewa, and Superior National Forests in 1991 and 1992 (Chequamegon National Forest). The program was designed to assess annual differences in bird relative abundance, and to attribute changes in numbers to habitat changes on the forest, or to natural fluctuations in bird numbers. Data collected from 1991 to 1994 or 1992 to 1994 have provided information on annual variation among guilds and individual species, and on relative densities of species within representative cover types on the Forests. A total of ten species (all Forests total) showed significant trends during the monitoring period. The White and Red-breasted Nuthatches, Yellow-bellied Flycatcher, Alder Flycatcher, and Yellow-rumped Warbler increased in abundance over all years; while Swamp and Chipping Sparrows, Brown Creeper, Eastern Wood-Pewee, and Hairy Woodpecker decreased in abundance over all years. No simple explanation can be offered for a particular trend in annual variation; however, it is important to note that the monitoring activity is beginning to reach a state of longevity where trends are can be detected. Trends or lack thereof of trends will be useful in resolving potential problems within a National Forest or to support conclusions that a problem does not exist. This information can be used to aid forest management by providing information on forest cover types. Based on power analysis, a sufficient sampling regime is in place to detect reasonable changes in abundance for many forest birds, including many neotropical migrants.Item Monitoring Bird Populations on National Forest Lands: 1995(University of Minnesota Duluth, 1995-12) Hawrot, Rita Y; Hanowski, JoAnn M; Lima, Ann R; Niemi, Gerald JItem Monitoring Bird Populations on National Forest Lands: 1995(University of Minnesota Duluth, 1995) Hawrot, Rita Y; Hanowski, JoAnn M; Lima, Ann R; Niemi, Gerald JA habitat specific bird monitoring program was established on the Chequamegon, Chippewa, and Superior National Forests in 1991 and 1992 (Chequamegon National Forest). The program was designed to assess annual differences in bird relative abundances and to eventually distinguish between larger-scale trends and small-scale shifts in abundance. Data collected from 1991 to 1995 or 1992 to 1995 have provided information on annual variation and trends over time for individual species and community parameters and relative abundance within representative cover types on the Forests. A total of 16 species (all Forests total) had significant linear trends during the monitoring period. The Great-crested Flycatcher, Blue Jay, Red and White-breasted Nuthatches, Veery, Brown Thrasher, Northern Parula, Chestnut-sided Warbler, Yellow-rumped Warbler, Canada Warbler, Swamp Sparrow, and Evening Grosbeak increased in abundance over all years; while the Hairy Woodpecker, Winter Wren, Red-eyed Vireo, and Indigo Bunting decreased in abundance over all years. The Red-eyed Vireo also had a decreasing trend in the Ottawa National Forest and decreased consistently in the Apostle Island National Lakeshore. No single explanation can be offered for a particular trend in annual variation; however; it is important to note that the monitoring activity has reached a state of longevity where trends can be detected. Trends or lack thereof of trends will be useful in resolving potential problems within a National Forest or to support conclusions that a problem does not exist. Results from the monitoring can be used to aid forest managers by providing information on bird/habitat associations within forest cover types. Based on power analysis, a sufficient sampling regime is in place to detect reasonable changes in abundance for many forest birds, including many neotropical migrants.Item Monitoring Bird Populations on National Forest Lands: Chequamegon National Forest, 1993(University of Minnesota Duluth, 1993) Hawrot, Rita Y; Hanowski, JoAnn M; Lima, Ann R; Niemi, Gerald JA habitat specific bird monitoring was established on the Chequamegon National Forest in 1992 (see Hanowski and Niemi 1992). The Objectives of the program were to: (1) establish the physical layout of the monitoring program; (2) monitor abundance of common bird species in the Forest; (3) begin refining avian/habitat relationships used to assess forest management activities on breeding bird abundance and distribution; and (4) explore similarities and differences in habitat data collected and the U.S. Forest Service forest types. An additional goal for 1993 monitoring was to make statistical comparisons between 1992 and 1993 bird abundance.Item Monitoring Bird Populations on National Forest Lands: Chippewa National Forest, 1993(University of Minnesota Duluth, 1993) Montgomery, Kent; Hanowski, JoAnn M; Lima, Ann R; Niemi, Gerald JA habitat specific bird monitoring program was established on the Chippewa National Forest in 1991 (see Hanowski and Niemi 1991b, 1992b). The objectives of the program were to: (1) establish the physical layout of the monitoring program (2) monitor abundance of indicator bird species that have been specified by the Forest; (3) monitor abundance of common bird species in the Forest; and (4) begin refining avian/habitat relationships used to assess forest management activities on breeding bird abundance and distribution. Additional goals implemented during 1992 were to: (1) determine the power of statistical analyses in terms of detecting annual differences for a variety of bird community, guild, and species specific parameters; and (2) explore similarities and differences in habitat data collected and the U.S. Forest Service forest types. Objectives for 1993 focused on making statistical comparisons between 1991, 1992, and 1993 bird abundance.Item Monitoring Bird Populations on National Forest Lands: Superior National Forest, 1993(University of Minnesota Duluth, 1993) Pearson, Carol W; Hanowski, JoAnn M; Lima, Ann R; Niemi, Gerald JA habitat specific bird monitoring program was established on the Superior National Forest in 1991 (see Hanowski and Niemi 1991, 1993). The objectives of the program were: (1) to establish the physical layout of the monitoring program; (2) to monitor the abundance of indicator bird species specified by the Forest; (3) to monitor the abundance of common bird species on the Forest; and (4) to begin refining avian/habitat relationships used to assess forest management activities on breeding bird abundance and distribution. Additional goals for 1992 monitoring were: (1) to make statistical comparisons between 1991 and 1992 bird abundance; (2) to determine the power of statistical analyses in terms of detecting annual differences for a variety of community, guild, and species specific parameters; and (3) to explore similarities and differences in habitat data collected and the U.S. Forest Service forest types. Added objectives for 1993 were: (1) to analyze avian population trends detected after three years of monitoring; and (2) to reassign forest types based on field inspection of stands identified in 1992 as having questionable forest type classifications.Item Monitoring Bird Populations on Three Great Lakes National Forests: 1991-1996(University of Minnesota Duluth, 1996) Hawrot, Rita Y; Hanowski, JoAnn M; Lima, Ann R; Niemi, Gerald JA habitat specific bird monitoring program was established on the Chippewa and Superior National Forests in 1991 and the Chequamegon National Forest in 1992. The program was designed to assess annual differences in bird relative abundances and to eventually distinguish between larger-scale trends and small-scale shifts in abundance. Data collected through 1996 have provided information on annual variation and trends over time for individual species and community parameters and relative abundance within representative cover types on the Forests. A total of 19 species (all national forests combined) had significant linear trends (P less than or equal to 0.05 for linear contrast) from 1991 or 1992 to 1996. Fourteen out of 19 (74%) increased and five (26%) decreased in abundance. In the Chequamegon, 10 out of 13 species (77%) increased from 1992 - 1996 and three species (23 % ) decreased during that time period. Six out of nine species ( 67 % ) increased from 1991 - 1996 in the Chippewa and nine species (33%) decreased. In the Superior, five species (83%) increased over the period of the monitoring and one species (17%) decreased from 1991 - 1996. Four species had the same significant linear trends in two out of three of the national forests: the Yellow-bellied Sapsucker increased in the Chequamegon and Superior National Forests; the Blue Jay increased in the Chequamegon and Chippewa National Forests; the Ovenbird increased in the Chippewa and Superior National Forests; and the Purple Finch decreased in the Chippewa and Superior National Forest. One species, the Hermit Thrush, had the same increasing trend in all three national forests. A change in methodology in 1994 (sampling within a limited radius vs an unlimited radius) is likely responsible for increases in 10 out of 19 (53%) species. A single explanation can not be offered for the _significant trends in the other species. Results from the monitoring can be used to aid forest managers by providing information on bird/habitat associations within forest cover types. Trends from long-term monitoring will be useful in resolving potential problems within a national forest or to support conclusions that a problem does not exist. Cumulative number of species that have a total number of observations of at least 25 (rare species) increases with each year of monitoring. Based on power analysis, a sufficient sampling regime is in place to detect reasonable changes in abundance for many forest birds, including many neotropical migrants.