Ongoing Research
January 1995 - December 1996
Contaminants
PCB Congeners in Marsh Birds in Green Bay Coastal Wetlands
Investigator: Deborah L. Swackhamer
Duration: August 1995 to July 1997
Funding Source: U.S. Fish and Wildlife Service,
Green Bay Ecological Services Office
Project Location: Green Bay, Wisconsin; University of Minnesota, Minneapolis
Green Bay has been highly contaminated with PCBs, and is designated as an "Area of Concern" by the International Joint Commission of the Great Lakes. PCBs are persistent, toxic pollutants that bioaccumulate, and have been shown to cause detrimental effects in wildlife and fish-eating bird populations in Green Bay and other locations in the Great Lakes. There has been little work done on the effects of toxic pollutants on passerines or marsh birds. The yellow-headed blackbird (Xanthocephalus xanthocephalus) feeds almost exclusively on aquatic insects during its breeding stage, and thus it is during this stage that eggs and nestlings are exposed to PCBs and are potentially subjected to toxic effects.
In conjunction with an ongoing project on yellow-headed blackbirds, the objectives of this project are to determine PCB concentrations in adult and nestling blackbirds from 2 field sites in Green Bay, and to relate observed PCB concentrations with reproductive and population parameters.
PCB concentrations in yellow-headed blackbirds ranged from 20 ng/g to 380 ng/g wet weight, averaging 210 ng/g. Lipid-normalized concentrations ranged from 300 ng/g to 17 ug/g, with an average of 10.7 ug/g. Eggs had less variability in their concentrations, and averaged 390 ng/g wet weight and 10.3 ug/g lipid weight. Despite the variability in the PCB concentrations in the birds, there was no relationship of PCB concentration to the skewed sex ratios found in the exposed population.
Human Activities, Management, and Conservation
Biodiversity Monitoring: Breeding Productivity,
Habitat, and Winter
Distribution of Nongame Birds
Investigators: David E. Andersen and Francesca
J. Cuthbert
Students: James C. Manolis, M.S./Ph.D. and Ethan F. Perry, M.S.
Duration: September
1991 to May 1997
Funding Sources:U.S. Global Climate Change Research Program
U.S. Fish and Wildlife Service Cooperative Research Units Center
U.S. Fish and Wildlife Service, Region 3 Division of Migratory Birds
and Refuge Biology
U.S. National Biological Service, Division of Cooperative Research
Project Location:Chippewa National Forest, Minnesota
Minnesota Cooperative Fish and Wildlife Research Unit
Recent declines in forest songbird populations have received considerable attention, and appear pronounced in some species in eastern North America. These declines have been attributed both to fragmentation/loss of breeding habitat and to deforestation of neotropical wintering habitat, but in many cases it is difficult to discern which factor is most important. Few long-term population studies have been conducted in extensive forest tracts, and even fewer have monitored breeding productivity along with analysis of vegetation. Breeding productivity information will be vital for developing sound management practices.
During May-July of 1992-1996, we monitored nesting success of forest birds in the Chippewa National Forest, Minnesota. We established six 40-50 ha permanent plots in a mature (ca. 80 years post-harvest) maple-basswood forest, and during the 5-year study period located and monitored 1,423 nests of 46 species. Traditional nesting success estimates were 54% for all species combined, and 38% for open-cup nesting neotropical migrants. In 1993 and 1994, we investigated effects of clearcut edges on reproductive success using artificial and natural nests. In 1993, 61% of artificial nests placed 0-10 m from clearcut edge were depredated, compared to 38% of nests placed 200 m from edge (P < 0.001). In 1994, predation rates were higher at the edges (34%) than at distances 25-200 m from edge, (18-22% P < 0.01). Beyond 25 m there was no apparent edge effect. These results suggest that edge effects observed in highly fragmented landscapes may also occur in predominantly forested regions.
In addition to monitoring nesting success and evaluating effects of edge on reproduction, we established 72 permanent point count stations (12 on each plot) and conducted 3-4, 100 m fixed-radius counts at each station between 1 June and 15 July of 1992-1996. Vegetation and habitat variables were measured at all nest and point count locations. In 1995, we also began investigating the nesting distribution of least flycatchers (Empidonax minimus) on our permanent plots. Several alternative hypothesis related to clumped nesting were tested, including differences in habitat characteristics and potential food resources, predator deterrence, and the potential for extra-pair copulations. We mapped the distribution of territorial male flycatchers through the breeding season, and are evaluating the effect of location within the nesting aggregation on nesting success. Data analyses for this portion of the project are ongoing.
The Effect of Human Disturbance on the Endangered Great Lakes Piping Plover
Investigator: Francesca J. Cuthbert
Students: Lauren Wemmer, Ph.D., Alice Doolittle,
M.S., and Lisa Climo, M.S.
Duration: May 1994 to June 1997
Funding Source: U.S. Fish and Wildlife Service,
East Lansing Field Office,
Michigan
Project Location: Northern Michigan and Atlantic Gulf Coast
This study addresses several aspects of piping plover (Charadrius melodus) biology and management needed for recovery of the endangered Great Lakes population. Work was done on the breeding population in northern Michigan and also on wintering birds along the Atlantic Gulf Coast.
Winter ecology and distribution: Objectives were to locate plovers wintering along the Gulf Coast, determine daily patterns of habitat use, identify plovers from reading leg band combinations and evaluate habitat quality. Although several hundred piping plovers were located, only l was identifiable (banded) from the Great Lakes population. This bird was found on Marco Island, FL and is an individual that has nested at Grand Marais, MI. Based on observation of plovers in winter, analysis of winter habitats was conducted to determine if plovers select wintering sites containing certain configurations of landcover components. A Geographic Information System was used to calculate the areas of landcover types within one km of shorebird sites (both occupied and unoccupied by piping plovers) on the Gulf Coast of Florida. Results of statistical tests indicated a significant difference in three cover types between plover and non-plover sites. Percentage of coastal stand and open water were significantly higher around plover sites than non-plover sites; percentage of marsh was significantly lower around plover sites than non-plover sites. These results indicate that piping plovers are selecting high energy shorelines that are sparsely vegetated. This analysis will be expanded to include an examination of land use, land ownership and human population density to identify conservation concerns and provide additional management guidelines for wintering piping plovers.
Breeding population research: We continued to monitor the breeding population of piping plover in northern Michigan. The number of nesting pairs increased from 21 to 23 from 1995 to 1996. An effort to develop a population model is continuing using recent data. This model incorporates use of captive rearing to enhance the population. Work to identify important habitat features and to evaluate habitat availability in northern Michigan was continued in 1996. All active plover sites and important historical nesting sites in northern Michigan were photographed using aerial videography. Sites were ground truthed and data on human disturbance and prey availability were collected for integration into the evaluation of habitat requirements of plovers during the breeding season.
Effects of Land Use, Sediment, and Temperature on the Distribution of Benthic Invertebrates and Fish in the Whitewater Watershed
Investigator: Bruce Vondracek
Students: Brian Nerbonne, M.S. and Carson Cox,
M.S.
Duration: June 1996 to June 1998
Funding Source: Minnesota Pollution Control
Agency
Project Location:Olmstead, Wabasha, and Winona Counties, Minnesota
Minnesota Cooperative Fish and Wildlife Research Unit
Conventional agricultural practices have been shown to have several negative effects on streams. Runoff containing fertilizers, pesticides, or herbicides can result in direct mortality of stream organisms. Conventional agricultural land use also deposits large amounts of sediment in streams, which impacts habitat for aquatic organisms. Best management practices (BMPs) such as vegetated buffer strips or no-till plowing have been purported to reduce sediment delivery rates. The goal of our study is to determine if BMPs are beneficial to instream organisms and stream quality.
The objectives of this study are to: 1) evaluate selected sites to determine effects of stream water temperature, sediment, and substrate particle composition on fish and invertebrate community structure, and 2) evaluate potential changes in substrate composition and the associated aquatic community along streams in parks, wildlife management areas, and where best management practices have been implemented.
In 1996, we sampled sites on the three main branches of the Whitewater Watershed. Agricultural sites were selected to include both conventional and BMPs. We also sampled several sites with natural vegetation to use as references for comparison. By design, we selected conventional and BMP sites along woody or grass buffers in clusters to characterize local effects and minimize larger scale effects. Fish and benthic invertebrates were sampled at each site to determine community composition. Physical habitat assessments were also conducted to examine both instream and riparian conditions.
Significant differences between land use and instream physical habitat were apparent. Conventional sites with woody buffers had larger angles of repose and more exposed soil than other sites. Conventional sites with woody buffers had significantly higher percentages of fine particles in the substrate than along grass-buffered sites or BMP wooded sites. This suggests that woody buffers may have higher sediment delivery rates than other types of land use.
Ongoing analysis will include calculating indices of biotic integrity for both fish and benthic invertebrates to determine whether instream biota responds to differences in instream and riparian habitat. Sampling in 1997 will incorporate methods used in summer 1996, but additional data will be collected in buffer strips.
Impact of Management Intensive Grazing Practices
on the Stream
Biota and Stream Habitat of Five Southeastern Minnesota Farms
Investigator: Bruce Vondracek
Students: Julia Frost, M.S. and Laurie Sovell, M.S.
Duration: June 1994 to
June 1998
Funding Source: Minnesota Institute for Sustainable Agriculture
Project Location:Dodge, Goodhue, Scott, and Winona Counties, Minnesota
Minnesota Cooperative Fish and Wildlife Research Unit
The National Research Council's 1989 report entitled "Alternative Agriculture" identified a number of environmental and economic problems associated with conventional U.S. agriculture including surface water and groundwater pollution, and soil erosion. Management Intensive Grazing (MIG) is a sustainable farming system increasingly employed by farmers in response to these problems, under which plots of grass are grazed by livestock rotated among numerous small paddocks.
From 1994 to 1996, aquatic biota and stream habitat were monitored as part of a team approach to evaluate the economic, social, and ecological impacts of MIG practices on farms in southeastern Minnesota. Water chemistry, physical habitat, benthic macroinvertebrate, and fish data were collected from five streams on MIG farms and paired conventional farms (continuously-grazed or row cropped) to compare water quality impacts of these farming systems. In addition, the influence of grass and woody riparian buffer zones on stream habitat and biota were evaluated.
Principal Components Analysis distinguished study sites by stream, suggesting the importance of evaluating the influence of farming practices within stream systems. Within stream systems, study sites were distinguished by farming practice for water chemistry, physical habitat, and benthic macroinvertebrate variables. Fecal coliform and turbidity were consistently higher at conventional sites. Physical habitat variables that distinguished sites include degree of shading, sediment levels, exposed streambank soil, and width to depth ratios. Sites with woody riparian buffers had higher levels of fine sediments and substrate embeddedness, more exposed streambank soil, and larger width to depth ratios. On one stream, levels of fine materials and embeddedness were greater at the conventionally-grazed farm than at MIG farms. Hilsenhoff's Family Biotic Index and % Dominance suggested better conditions along woody riparian stations. Fish abundance and diversity varied among all MIG sites and are likely related to inherent differences between streams sampled. Fish abundance levels and species diversity were similar between paired sites and MIG sites. Based on the results of the monitoring study, research efforts for 1997 will be directed toward: 1) Determination of the mechanisms involved in specific cattle grazing disturbance events to streams, 2) Development of a water quality monitoring toolbox for use by farmers to continue on-farm assessment of management practices.
Individual-Based Walleye Simulation Model
Investigators: Ira Adelman and Yosef Cohen
Student: Jingyin Li, Ph.D.
Duration: July 1996 - July 1997
Funding Source: Minnesota Department of Natural
Resources
Project Location: Department of Fisheries and Wildlife, University
of Minnesota
Walleye (Stizostedion vitreum vitreum) stocking has been a standard management practice in Minnesota for over half a century. Since the 1950's, more than 7.5 billion young and adult walleye have been stocked in numerous Minnesota waterbodies. This walleye stocking program comprises an important portion of the budget of the Minnesota Department of Natural Resources (MNDNR), Section of Fisheries. Although walleye stocking has been extensively practiced in North America, its effectiveness has not been investigated quantitatively on a broad scale.
In a previous study, we used data from MNDNR lake surveys and stocking records to examine the effects of walleye stocking on the abundance, size of fish, and year-class strength in walleye populations and to determine to what extent and under what conditions these effects occurred. We used 4,470 lake surveys from 1,924 lakes and 20,634 walleye stocking records from 1,716 lakes. These data provided a vast amount of information on the effects of stocking on fish populations, which was not available from site-specific studies reported in the literature. Based on our analysis of these data, we found that stocking increased the abundance of the stocked year class, with a larger increase in lakes without natural walleye reproduction than in lakes with natural walleye reproduction. However, stocking also had negative effects. These were a decrease in the strength of the year classes adjacent to the stocked year class in lakes with natural walleye reproduction and a decrease in the weight of fish in lakes with and without natural walleye reproduction. Walleye stocking is most likely to contribute to walleye population abundance in lakes where walleye reproduction is limited but food is not limiting. This study confirms what fisheries managers have long believed but had not been able to verify on a broad scale, i.e., walleye should not be stocked in lakes where natural reproduction occurs.
To further explore the effects of walleye stocking, we developed an individual-based simulation model for walleye populations based on data from a variety of literature on walleye populations. The model is window and menu based, and has a user friendly interface. The model has the capacity to incorporate information about system carrying capacity, stocking strategy, and fishing pressure, and predicts how stocking and other management strategies will affect the fish population. The current model replicates the empirical findings of the effect of stocking on the abundance and body size of fish in the stocked and adjacent year classes, and indicates that density-dependent competition is one of the important mechanisms in determining these effects. As a useful decision supporting tool, this model can also be used to investigate the effects of other management strategies, such as various fishing regulations, on fish population dynamics.
Status Assessment for the Great Lakes Population of Common Terns
Investigator: Francesca J. Cuthbert
Student: Kris Timmerman, Ph.D.
Duration: September 1995 to December 1996
Funding Source: U.S. Fish and Wildlife
Service
Project Location: University of Minnesota, St. Paul
Common tern (Sterna hirundo) population trends for the last two decades (1976-1995) were reviewed for one Canadian province (Ontario) and nine U.S. states to determine status, trends, and general threats to the Great Lakes population of this species. According to the most recent estimates for the Great Lakes, there were approximately 10,000 pairs of common terns nesting in this region during 1989-1990. Historical data do not exist that allow an estimate of the number of common terns in the Great Lakes prior to settlement and during the period of more intensive development during the 1900's. Significant numbers (>1,000 pairs) occur only in Michigan, New York, and Ontario. Minnesota and Wisconsin have typically had smaller numbers over the past several decades. Current estimates are 500-600 pairs for each state. Vermont has maintained approximately 50-150 pairs during the past decade. Four states have 0 to fewer than 50 pairs. Because no consecutive comprehensive international census efforts have been conducted, it is difficult to interpret trends from existing census data. The general consensus is that some populations have declined significantly (e.g., Ohio) and others have increased (e.g., Vermont). Based on a comparison of data available for Canadian and U.S. waters in the 1970's and 1989-1990, H. Blokpoel and W. Scharf reported a signficant increase in breeding pairs of common terns. However, H. Blokpoel and Tessier reported a 26% decrease in Canada between the 1970's and 1990.
Common terns are affected by a diversity of threats in the Great Lakes region. These include: habitat deterioration and loss, predation, competition for nesting habitat with Ring-billed Gulls (Larus delawarensis), human disturbance and contaminants. Considering population size, number of jurisdictional units and number and remoteness of colony sites, the knowledge of common tern biology, population threats and status at many colonies is extensive. In response to threats, many methods to enhance colony productivity and protection have been developed. Most efforts have focused on: habitat management (including habitat restoration, enhancement or creation), predator control, reduction of competition for nest sites, and prevention of human disturbance. The most critical missing conservation component for the population is a region-wide monitoring and management plan that allows tracking population trends through time.
Trophic ecology of young-of-the-year Walleye in Minnesota rearing ponds
Investigator: George R. Spangler
Student: Alan McClure, Ph.D.
Duration: June 1991 - June 1998
Funding Source: Minnesota Department of Natural
Resources
Project Location: University of Minnesota, St. Paul
Investigation into the factors leading to disparate fingerling production of walleyes (Stizostedion vitreum) in winterkill rearing ponds has revealed that differences exist between ponds in the nutrient pathways leading to fish production. Stable isotope analyses to ascertain the trophic pathways leading to walleye production in several rearing ponds have been made for 40 samples from 1992. Of the 40 samples, twenty-two are samples from the Gunclub Pond, sixteen from the Camp Galilee Pond, and two from La Lake. Samples from Gunclub Pond and Camp Galilee Pond include all trophic levels, including primary sources, consumers, and top predators. The relationships between isotope ratios observed in different trophic categories generally conforms to expectations. Consumers have isotope ratios about 3 parts per thousand (3_) heavier for nitrogen and 1 - 2_ heavier for carbon than likely prey or sources of primary production. The isotope ratios of the primary producers that were sampled can be explained well by processes that are known to influence the isotopic composition of source pools and fractionation.
A micro-biochronology of daily otolith growth increments will be coupled with the nutritional pathway analyses to identify significant events in the summer temporal history of rearing-pond fish. Initial attempts to develop the biochronology have failed to produce unambiguous otolith patterns. This is due to allometric growth in the otoliths which must be accounted for in the measurements. Thus far, we have shown that it is necessary to use information from many transects to estimate otolith growth increments. Our procedure is to capture pixel data along five transects within a small part of the growth record at the center of each otolith. The basic idea is to divide each growth increment into a part due to location on the otolith (angle and radius), and a part due to age, past growth, or environment. This allows otolith shape to change as the fish grows. The angle between a given transect and individual growth rings is used to predict this effect at all distances along all the transects. This results in a factor that can be used to expand or contract the spatial scales of each transect so that distance along the transect corresponds to the same time interval on all the transects. When composite descriptions of the temporal history of fish growth within the ponds have been constructed, we will attempt to correlate the nutritional histories with the time series to identify key periods in the early growth of the fish.
Applied Ecology
Age and Growth of Lake Herring in Lake Superior
Investigators: George R. Spangler and Donald L. Pereira
Student: Stephanie West
Todhunter, M.S.
Duration: September 1993 through present
Funding Source: Minnesota Department
of Natural Resources
Project Location: Lake Superior, Department of Fisheries and Wildlife
The shallow-water cisco, (Coregonus artedii), also known as the "lake herring" has been rebounding in abundance in Lake Superior since 1980, nearly three decades after the collapse of the lake trout (Salvelinus namaycush) community. Lake herring in Lake Superior suffered drastic declines in the 1950s and 60s and remained at low abundance through the 70s and early 80s. However, there have been several large year classes recently and it is generally believed that the lake herring population is recovering lakewide. A comprehensive record of relative growth for this period may lead to a better understanding of the complex dynamics involved in lake herring growth and abundance. Comparisons of growth histories between different geographic regions of the lake should help us to understand whether regional differences between stocks should be taken into account in the lakewide management of this species. To further understand lake herring growth dynamics, we are developing separate biochronologies for four different sites on Lake Superior. The chronologies span a period extending back from the present until the early 1960s and are based on scale sample collections on loan from the Wisconsin DNR, Minnesota DNR and the Ontario Ministry of Natural Resources. Once the chronologies have been established, they will be compared to site specific temperature and abundance time series. Lake herring growth is thought to be density dependent, and thus, should reflect differences in their own densities, as well as the abundance of competing species. If cisco growth is sensitive to annual variations in water temperature, we expect to find some degree of correlation between temperature time series and the lake herring biochronologies.
Assessing Ecological Structure, Function, And Dynamics Of Undisturbed And Restored Northern Prairie Wetlands
Investigator: John R. Tester
Student: Paul M. Mayer, Ph.D.
Duration: September 1992 - to present
Funding Source: U.S. Bureau of Reclamation
Project Location: Waubay National Wildlife
Refuge
University of Minnesota, St. Paul
The inferred goal of restoration is to reestablish ecological structure and function including characteristics such as species diversity, nutrient cycling, decomposition rates, food web structure, and productivity. However, previous studies have revealed that recovery is incomplete or unattainable for at least some of these characteristics. The purpose of our study was to determine if restoration mitigates prairie wetland losses by evaluating whether or not, over time, restored wetlands recover to a state ecologically similar to reference wetlands. We felt that this assessment may be best accomplished by measuring several indicators of structure and function chosen on the basis of current ecological theory. One prediction, for example, is that species diversity will be low in a recovering ecosystem while productivity and community respiration remain high. Therefore, in 1993-1995 we compared indicators in 10 restored and 10 reference prairie wetlands in South Dakota. Indicators included biomass production and respiration, chemical and nutrient levels, diatom species diversity, and decomposition indices. An additional transplant experiment was necessary to interpret the role of dispersal in recovery.
Preliminary data indicate that chemical and nutrient values such as pH and conductivity were highly variable within restored and reference groups but, overall were slightly lower in restored wetlands. Decomposition rates also were highly variable and were not influenced by drainage history. However, biological oxygen demand, one of 3 measures of production and respiration in this study, was higher in restored wetlands. These data support predictions by other researchers regarding the response of ecosystems to disturbance and their subsequent recovery.
Preliminary analysis of diatom communities indicates that a characteristic diatom flora may be identified in reference wetlands, a factor critical in developing useful ecological indicators. Furthermore, diatom species compostition in restored wetlands was dissimilar, indicating that random pioneering events may influence recovery trajectories of restored wetlands.
The diatom transplant experiment also supported the use of diatoms as indicators of recovery. Based on color, texture, and transparency of algae growing on the artificial substrates employed in the experiments, diatom communities apparently differed in reference and restored wetlands indicating that restored wetlands, and perhaps even individual wetlands, may harbor characteristic flora. Furthermore, diatom communities on the transplanted substrates appeared to shift to assemblages like those existing in the wetlands to which the substrates were transferred indicating that environmental conditions (and perhaps competition) and not dispersal events dictate community composition.
Assessing Wolf Population Structure
Investigators: L. David Mech and David E. Andersen
Student: Thomas J. Meier, M.S.
Duration: January 1994 to December 1996
Funding Source: U.S. Fish and Wildlife
Service, Patuxent Wildlife Research Center
U.S. National Biological Service, Alaska Science Center
Project Location: Denali National Park and Preserve, Alaska
Department of Fisheries and Wildlife, University of Minnesota
Department of Biology, University of California at Los Angeles
New techniques of nuclear DNA analysis, using highly variable microsatellite loci, make it possible to determine patterns of relatedness in local populations of animals. When combined with field data on the behavior of these animals, a detailed picture of local population structure may be obtained.
During an eight-year study of a wolf (Canis lupus) population in and around Denali National Park and Preserve, Alaska, 150 wolves from 41 packs were captured and radio-collared. Information has been gathered on movements, survival, and dispersal of individual wolves, as well as on patterns of territoriality and interchange of wolves between packs, and the formation and survival of wolf packs. Demographic histories of 34 Denali wolf packs have been compiled for a final project report to the National Park Service and an upcoming book on the park's wolf population.
Genetic samples from 130 Denali wolves have been analyzed for allele patterns at 20 microsatellite loci. Relatedness values have been calculated for each pairwise comparison of sampled wolves. A number of simulations have been performed to test hypotheses about patterns of genetic relatedness in the wolf population. As expected, genetic relatedness is higher for comparisons within packs than for those between packs. Genetic relatedness is also significantly higher between immediately neighboring packs than between more distant packs.
Field observations have shown that the mosaic of wolf packs in Denali is dynamic, with new packs being formed by dispersers, with some older packs dying out, and with interchange of wolves between existing packs. Also complicating the structure of the population are the founding of new packs by more than two wolves, the presence of multiple breeding females within some packs, and the possible exchange of genetic material by breeding between adjacent packs. Genetic comparison of known breeding pairs of wolves based on microsatellite DNA analysis reveals no evidence of intense inbreeding/incest among sampled pairs, suggesting that pack dynamics allow significant genetic mixing within the population.
By comparing specific alleles at each locus between potential parent/offspring pairs, and looking at complementarity alleles between potential mother/father/ offspring sets, assignments of parenthood can be made based on the genetic data. These will be compared with field data and overall patterns of genetic relatedness to get the most accurate picture to date of how the various packs in a wolf population relate to one another.
Eastern Praire Population Canada Goose Ecology
Investigators: David E. Andersen, Donald H. Rusch (WI Cooperative Wildlife
Research Unit) Mississippi Flyway EPP Technical Committee Duration: Ongoing
Funding
Sources: U.S. Fish and Wildlife Service
Mississippi Flyway Council (EPP Technical Committee)
Manitoba Department of Natural Resources
Minnesota Department of Natural Resources
Iowa Department of Natural Resources
Missouri Department of Conservation
Arkansas Game and Fish Commission
Canadian Wildlife Service
Project Location: Cape Churchill, Manitoba
Minnesota Cooperative Fish and Wildlife Research Unit
Wisconsin Cooperative Wildlife Research Unit
Eastern Prairie Population (EPP) Canada geese (Branta canadensis) breed in the Hudson Bay Lowlands in northeastern Manitoba. This group of birds migrates through southern Manitoba and western Minnesota, and historically wintered in Missouri and Arkansas. Because they nest in the sub-arctic, EPP geese exhibit wide variation in productivity and recruitment, and information regarding breeding ecology and population status is required to effectively manage harvest.
Research on breeding ecology of this population of arctic-nesting geese has continued since the 1960's, and information from these studies has been used to develop management and harvest strategies. Long-term monitoring of breeding density, nesting success, gosling production, and other breeding population parameters has resulted in information useful in modeling this populations. These on-the-ground data collection activities are ongoing annually.
These monitoring efforts occur in close proximity to the La Perouse Bay snow goose (Anser caerulescens caerulescens) colony, and over the past 20 years, snow goose use of the study area has increased dramatically. During the same period, breeding densities of Canada geese have dropped dramatically, and snow geese now dominate numerically in historic Canada goose brood-rearing areas. Currently, a research project designed to better understand the relationship between Canada and snow geese on the breeding grounds is under development.
Foraging Behavior of California Sea Lions at
San Miguel Island,
California
Investigator: Donald B. Siniff
Student: Sharon Melin, Ph.D.
Duration: September 1996 March 1997
Funding Source: National Marine Mammal Laboratory
Seattle, Washington
Project Location: University of Minnesota, St. Paul
San Miguel Island, CA
The project was initiated in September 1996 and focuses on describing the annual patterns of foraging behavior, movement and distribution of California sea lions (Zalophus californianus) at San Miguel Island, California. The purpose of this study is to better understand the ecological role of California sea lions in the California Current ecosystem.
The foraging behavior will be described through analysis of satellite telemetry and diving data from 20 adult female California sea lions collected over a three year period, 1994-1996. Foraging locations and summary statistics of diving behavior will be used to describe the foraging range of California sea lion females. The movement and distribution of animals along the California coast throughout the year will be determined using sightings of 3,500 animals branded and tagged as pups (representing 9 cohorts). The distribution of sightings by location, age and sex will be used to describe movement and distribution patterns of individuals by age and sex.
Insects and Anurans as Indicators of Wetland
Condition in the Prairie
Pothole Region of North Dakota
Investigators: David E. Andersen, Bruce Vondracek,
Ralph Holzenthall, Francesca
Cuthbert
Duration: January 1995 to December 1997
Students: David J. Anderson, M.S.
and Dorothy G. Bowers, M.S.
Funding Source: U.S. National Biological Service,
Northern Prairie Science Center
Project Location : Northern Prairie Science Center, North Dakota,
Minnesota Cooperative Fish and Wildlife Research Unit
Wetland complexes in the Prairie Pothole Region (PPR) of North Dakota have been severely impacted by agri-cultural practices. Efforts to evaluate the health of these wetland ecosystems may be hampered by their dynamic nature. A long-term, landscape-based approach may be needed for conservation efforts to succeed. To address this need, potential indicators of wetland condition are being evaluated across three ecoregions within the PPR. Two groups, insects and anurans (frogs and toads), are being assessed for their potential as biological indicators of wetland and landscape condition.
Insects have been useful in monitoringother aquatic habitats, and hold promise for wetland systems. For insects our objectives are to 1) develop an effective sampling strategy, 2) describe insect taxa richness and abundance in sampled areas, and 3) evaluate relationships between regional wetland condition and insect taxa richness and abundance. In spring and summer of 1995 and 1996, 21 sites were visited on three occasions each year. Insects were collected by placing light traps near six seasonal and semi-permanent wetlands within each site. Preliminary analysis indicates abundance and taxonomic richness were highest in the Red River Valley, intermediate in the Drift Plain, and lowest in the Missouri Coteau ecoregion. Sample composition also differed by ecoregion, with the Red River Valley dominated by Coleoptera, Missouri Coteau dominated by Diptera, whereas the Drift Plain had intermediate levels of both groups. These relationships may be important to consider for large-scale monitoring. Further analyses will examine possible relationships between land use and insect taxa richness and abundance.
During 1995 and 1996, we assessed theimpacts of land-use patterns on anuran populations. We conducted nocturnal calling and driving surveys three times each year at 21 sites in the PPR. Additionally, at several sites we used automated recorders to record calling anurans during four 10-minute intervals throughout the night. We detected nine species of anurans and preliminary data suggest that some anuran species are associated with land-use patterns. Relative abundances of the American toad (Bufo americanus) and the gray treefrog (Hyla versicolor/ chrysoscelis) appeared greater in grasslands than agricultural lands, whereas relative abundance of the Great Plains toad (B. cognatus) was greater in agricultural landscapes than in grasslands. Distributions of the gray treefrog and the Plains spadefoot toad (Spea bambifrons) were more extensive than previously documented, whereas distributions of the Canadian toad (B. hemiophrys) and the northern leopard frog (Rana pipiens) were less extensive. Relative abundance and distribution of some anurans species may be related to land-use patterns at multiple geographic scales.
Paleolimnology: Reconstructing the Chronology
of Fish Residency in Alpine
and Subalpine Lakes of Glacier National Park, Montana
Investigators: Dirk Verschuren and Herbert E. Wright
Duration: January 1996 to
August 1997
Funding Source: U. S. National Biological Service
Project Location: Glacier
National Park
University of Minnesota, Minneapolis
The westslope cutthroat trout (Oncorhynchus clarki lewisi ) has declined throughout much of its original range in Montana, Idaho, British Columbia, and Alberta due to destructive land-use practices and ecological disturbance caused by the introduction of non-native fishes. Surviving genetically pure populations in headwater lakes of Glacier National Park could play an important role in the managed recovery of cutthroat trout fisheries throughout the region. However, several of these populations occur in lakes above barrier falls or without direct stream access, so that uncertainty exists whether the trout could have naturally invaded these lakes. This project uses paleolimnological techniques to determine whether native trout fisheries in selected lakes are indeed indigenous or became established through undocumented introductions before the establishment of Glacier National Park in 1910. Evidence is derived from examination of the vertical distribution of zooplankton remains preserved in the lakes' profundal sediments. This approach is based on the premise that introduction of planktivorous trout to a previously fishless lake would have caused substantial changes in the local zooplankton community that can be detected in the sediment record.
In a pilot study, we tested the validity of using fossil ephippia (diapause eggs) of the fish-sensitive cladoceran Daphnia as an indicator for historical Daphnia population densities, and by extension for the presence of a trout fishery. This was done by demonstrating correlation between current Daphnia population density and the density of ephippia in surficial sediments of eight headwater lakes with and without fish. In the current project we aim to further validate the technique by analyzing the vertical distributions of zooplankton remains in sediments of lakes with contrasting but documented fishery histories.
In July and August of 1996, sediment cores were collected in six headwater lakes of Glacier National Park. Three of these are warmwater subalpine lakes (mid-summer SWT > 16·C) that are potentially inhabited by two groups of fish-sensitive zooplankton, the cladoceran Daphnia and the larvae of phantom midges, Chaoborus. The three other lakes are coldwater alpine lakes (mid-summer SWT < 14·C) where Chaoborus cannot occur but Daphnia does. The group of coldwater lakes includes Arrow Lake, with an indigenous trout fishery; and Poia and Camas Lakes, originally fishless lakes to which cutthroat trout had been introduced. The group of warmwater lakes includes John's Lake, which is too shallow for fish to overwinter; Babbe Lake, where fish do not occur because of its isolated setting; and Swiftcurrent Ridge Lake, an isolated lake to which cutthroat trout and other fish were introduced during the 1920s through 1940s. Preliminary data on fossil zooplankton assemblages in the sediment record of Swiftcurrent Ridge Lake confirm the expected drastic reduction of Daphnia population density around the time of trout introduction.
Relating Behavior and Microhabitat Use to Growth in Stream Resident Trout
Investigator: Bruce Vondracek
Student: Gerold C. Grant. Ph.D.
Duration: September 1992 to June 1997
Funding Sources: Cargill Fellowship
Kalamazoo Chapter of Trout Unlimited
Sigma Xi
Special Projects Foundation of the Big Game Club
Project Location: Valley Creek, Washington County, Minnesota
Minnesota Cooperative Fish and Wildlife Research Unit
It has been suggested that stream trout chose microhabitats that optimize their net energy intake and therefore maximize growth. To maximize energy intake, stream trout likely occupy microhabitats with low water velocity to minimize swimming costs, but close to high velocity water, which supplies more drifting prey. Past studies on microhabitat use have relied upon single observations of fish position to quantify microhabitat use. No studies have successfully related microhabitat use and behavior to growth in natural environments. We are approaching this question using new techniques to quantify microhabitat use, behavior and growth of trout in Valley Creek. Our techniques include using submersible video cameras and a time lapse recorder to remotely observe trout behavior and microhabitat use. In addition to traditional growth measurements, we are measuring RNA/DNA ratios in muscle tissue biopsies, which we have shown to reflect recent growth rates in adult brown trout. This was the first study in which RNA/DNA ratios were measured from a tissue sample from adult fish without sacrificing the animal.
In 1995 and 1996, we quantified growth rates of sympatric brook (Salvelinus fontinalis), brown (Salmo trutta) and rainbow (Oncorhynchus mykiss) trout in Valley Creek throughout the year. In summer of both years, we collected data on microhabitat use and behavior using time lapse video recordings, and quantified habitat availability. In summer 1996, we quantified availability of drifting prey in Valley Creek, as well as diet composition in the three species of trout, to determine how much these fishes rely on drifting prey items. Hypotheses about trout microhabitat use will be tested by comparing microhabitat use and growth rates to those predicted by models for drift-feeding salmonids.
In addition to the above research, an investigation of reproductive behavior of brook and brown trout was performed during 1995. Spawning trout were monitored over 24-hour periods using time lapse video recordings and submersible video cameras illuminated by infrared lights. Time budgets were estimated from observations of 13 redds (spawning nests) of brook and brown trout. We quantified the percent time redds were occupied by male and female trout of each species, and the percent time females spent excavating the nest, spawning and covering the eggs as well as the number of males present and percent time males spent in agonistic behavior. Further analysis of these recordings will be performed to quantify intraspecific spawning activity in sympatric brook and brown trout.
Winter Ecology of Ferruginous Hawks in Colorado
Investigator: David E. Andersen
Student: David J. Plumpton, Ph.D.
Duration: July 1992 to June 1997
Funding Sources: U.S. Fish and Wildlife Service
U.S. Army
Rocky Mountain Arsenal National Wildlife Refuge
Project Location: Rocky Mountain Arsenal National Wildlife Refuge, Colorado
Minnesota Cooperative Fish and Wildlife Research Unit
The ferruginous hawk ( Buteo regalis), North America's largest buteo, was once found in most states west of the Mississippi River and the prairie provinces of Canada. Populations have been declining in recent decades, primarily due to loss of habitats and attendant declines in prey populations. Ferruginous hawks currently occupy one of the smallest breeding range of any North American buteonine hawk. First-year mortality is approximately 66%, yet little information exists regarding habits and habitat use of ferruginous hawks outside the breeding season.
Although Colorado supports a nesting population of ferruginous hawks, it contributes far more to the global population of ferruginous hawks in terms of the number that overwinter there. There is currently much concern for the ferruginous hawk, as large-scale conversion of winter habitat by human development proceeds. The ferruginous hawk was previously listed as a Category 2 species under the Federal Endangered Species Act.
In 1992, we initiated an investigation of the winter ecology of ferruginous hawks in eastern Colorado. Thirty-eight ferruginous hawks were equipped with radio transmitters and monitored for 1,325 hours during 148 complete winter days. Home range size and activity levels were not different between hawks in highly fragmented (urban and suburban) habitats and hawks using the Rocky Mountain Arsenal (single contiguous block of habitat). In the suburban site, ferruginous hawks appeared to modify their behavior to exploit small, isolated colonies of black-tailed prairie dogs (Cynomys ludovicianus), underscoring the importance of this prey resource during winter months. Prairie dog densities declined dramatically between the winters of 1993-94 and 1994-95 on the Rocky Mountain Arsenal, and ferruginous hawks numbers exhibited a concurrent drop on the arsenal, but not the suburban site.
Ferruginous hawks appear to be able to modify their behavior to exploit a variety of landscapes during the winter. As long as suitable prey are available, ferruginous hawks appear capable of exploiting urban and suburban landscapes. Unlike many other raptors that benefit from changes in urban and suburban landscapes, however, ferruginous hawks are dependent upon black-tailed prairie dogs during winter in eastern Colorado, and many human activities negatively impact this prey species.
Minnesota Cooperative Fish and Wildlife Research Unit
University of Minnesota
Department of Fisheries, Wildlife, and Conservation Biology
1980 Folwell Avenue, 138 Hodson Hall
St. Paul, MN 55108
phone: 612-624-3421
fax: 612-625-5299
coopunit@tc.umn.edu