1994 has been a year of substantial accomplishments, most of which are directly attributable to the University Field Station staff and the faithful users of the facility. I would, therefore, like to use this opportunity of thanking them all for their hard work and dedicated effort. I would particularly like to acknowledge Dr. Gordon Goldsborough for sacrificing so much of his time to Field Station administration. He acted very effectively as Director of the Station throughout the summer; he has again edited and formatted this report; he has, as 'Internet surfers' will know, established an impressive "Home Page" on the Worldwide Web; and he established the Station's first computer laboratory. For all of this and more, I thank him very much.

The support of the University through the Faculty of Science, the Faculty of Science Endowment Fund, the Office of the President and Physical Plant is gratefully acknowledged, as is the Natural Sciences and Engineering Research Council of Canada for the provision of an Infrastructure Grant. The efforts and support of the Fiends of the Field Station, and the financial support of Canada Trusts' Friends of the Environment Foundation are deeply appreciated as are the donations of many generous individuals.

Overall Use

The following table summarizes the overall use of the University Field Station since 1985.

	User Days
Year	Research	Courses	Schools	Other	Total
1985	2002	927	630	257	3709
1986	1558	559	639	866	3622
1987	1186	298	585	1214	3283
1988	1565	626	465	1196	3852
1989	1754	397	574	1304	4029
1990	1251	787	747	1547	4337
1991	912	712	727	2104	4455
1992	914	1096	1008	1742	4760
1993	1067	994	1317	2241	5619
1994	1314	1026	2091	1890	6321

In 1994 use of the Field Station increased by 12.5% over the previous year, by 33% over 1992, by 42% over 1991 and by 64% over 1988. The trend is obvious. The Station is being increasingly used in essentially all categories.

Research

Research activities increased by 23% over 1993 and the following specific projects were either initiated or continued during 1994.

• The effect of turbidity on predator-prey interactions in aquatic communities. Dr. Mark Abrahams and Mike Kattenfeld, Department of Zoology, University of Manitoba
• Biotic inventory and development of a low-impact self-guided trail in Oxbow Woods. Jennifer Barker, Environmental Science Program and Dr. Norm Kenkel, Department of Botany, University of Manitoba
• Sperm storage and the proximate mechanism of last-male sperm precedence in the Yellow-headed Blackbird. Dr. James V. Briskie, Department of Biology, Queen's University
• Patterns of frequency and abundance in parasite communities. Dr. Albert Bush, Department of Zoology, Brandon University
• Host-specificity in Brown-headed Cowbirds? A population-level approach. Dr. H. Lisle Gibbs, Department of Biology, McMaster University and Dr. Spencer G. Sealy, Department of Zoology, University of Manitoba
• The evolution and functions of Yellow Warbler alarm calls. Sharon Gill and Dr. Spencer G. Sealy, Department of Zoology, University of Manitoba
• Effects of pulsed and regular nutrient additions on algal, macrophyte and invertebrate communities in large littoral enclosures. Dr. L. Gordon Goldsborough and Rhonda L. McDougal, Department of Botany, Brandon University Dr. Brenda J. Hann, Department of Zoology, University of Manitoba Mandy B. Lloyd, Environmental Science Program, University of Manitoba
• Study of polyglycan secretions by benthic diatoms Dr. Richard Gordon and Natalie K. Bjorklund, Department of Botany, University of Manitoba
• Great Burdock (Arctium lappa) at Delta, Manitoba: demography and control measures. Kelly Graham and Dr. Norm Kenkel, Department of Botany, University of Manitoba
• Location and selection of Clay-colored Sparrow nests by Brown-headed Catbirds. Paula Grieef and Dr. Spencer G. Sealy, Department of Zoology, University of Manitoba
• Distribution of littoral Anomopoda in prairie potholes. Dr. Brenda J. Hann, Department of Zoology, University of Manitoba and Dr. Dorothy B. Berner, Department of Biology, Temple University
• An experimental determination of avian nest predation pressure in riparian habitats at Delta Marsh. Dr. Keith A. Hobson, Canadian Wildlife Service, Saskatoon, Saskatchewan, Dr. Spencer G. Sealy and Douglas Froese, Department of Zoology, University of Manitoba
• Neotropical migrant banding program at the University Field Station (Delta Marsh). Dr. Keith A. Hobson, Canadian Wildlife Service, Saskatoon, Saskatchewan
• Tree Swallows as bioindicators at Delta Marsh. Dr. Keith A. Hobson, Canadian Wildlife Service, Saskatoon, Saskatchewan
• Spatial and demographic patterns of a monodominant stand of Ostrich Fern (Matteucia struthiopteris). Dr. Norm C. Kenkel, Department of Botany, University of Manitoba
• Begging strategies of the parasitic cowbirds. Gabriela Lichtenstein, Department of Zoology, Cambridge University, England
• Manipulation of Yellow Warbler incubation behavior by cowbirds. D. Glen McMaster and Dr. Spencer G. Sealy, Department of Zoology, University of Manitoba
• Parasitism frequency on cowbird-egg ejectors, determined by direct observations. Dr. Spencer G. Sealy, Glen McMaster and Sharon Gill, Department of Zoology, University of Manitoba Diane L. Neudorf, Department of Biology, York University
• Behavioral reactions of some acceptor species to cowbird eggs added experimentally to their clutches. Dr. Spencer G. Sealy and Janice Lorenzana, Department of Zoology, University of Manitoba
• Do parasitic Brown-headed Cowbirds avoid already-parasitized nests? Dr. Spencer G. Sealy and Diane Beattie, Department of Zoology, University of Manitoba Graham Stinson, Environmental Science Program, University of Manitoba
• Temporal and spatial distribution of littoral invertebrate communities in Crescent Pond and Blind Channel. Leanne Zrum and Dr. Brenda J. Hann, Department of Zoology, University of Manitoba

I would like to expand on two of these projects as they represent thrilling new prospects for the future of the Field Station:

Delta Marsh Bird Observatory (DMBO)

When birds start to disappear from our forests we know there is something seriously wrong with our environment. Recently there have been reports of population declines in a number of neotropical bird species. Possible reasons probably include changes to factors in both wintering and breeding grounds. To develop conservation strategies for migrant birds, we first need to know their status, population trends and the causes of population change. Monitoring programs are required to detect and measure change. The best way to monitor these populations is to sample them as they migrate from within the boreal forest, taiga and tundra through southern Canada.

From 1992 to 1994, Dr. Keith Hobson, Paula Grieef, Heidi den Haan, acting for the Canadian Wildlife Service (C.W.S.), conducted a monitoring/banding program at the University Field Station (Delta Marsh), that was essentially a replication of a similar program conducted ten years earlier by Dr. Spencer Sealy and Heidi den Haan. In 1994 the Delta Marsh Bird Observatory (D.M.B.O.) was established at the Field Station. It is Manitoba's contribution to providing continued information on migratory songbirds. It is one of five working banding stations in Canada and part of the C.W.S. "Canadian Landbird Monitoring Strategy". D.M.B.O. is destined to become one of a network of 260 Monitoring Avian Productivity and Survivorship stations across North America. D.M.B.O. will operate as a non-profit organization and its board of directors are Paula Grieef, Heidi den Haan, Dr. Keith Hobson (C.W.S.), Dr. Bob Jones (Manitoba Natural Resources) and Dr. Spencer Sealy (Department of Zoology).

The University Field Station has a long established record in avian research and its new alliance with D.M.B.O. is an exciting and welcome development.

Prairie Wetland Ecology Team (PWET)

Canada is a nation of wetlands. Approximately 14% of the country's total land area is covered by shallow bodies of water that are home to diverse plant communities, abundant waterfowl and other aquatic life. Yet, these important resources are increasingly subject to damage from external influences. Over the past century many prairie wetlands were drained to support agricultural production. Those that remain are contaminated by nutrients, metals and acids and invaded by foreign animal and plant species.

The extent to which these external factors will upset the delicate natural balance of prairie wetlands is largely unknown. One way to gain further understanding is to conduct experiments in small areas of the wetland where these factors can be introduced in controlled quantities and the resulting response can be carefully monitored. This is being done in a series of experiments in channels of the Delta Marsh bordering the University Field Station. In 1991, large floating platforms (5 m x 5 m) were deployed in the Blind Channel. Each summer, plastic curtains are attached to the platforms and embedded in bottom sediments to isolate about 20,000 liters of marsh water. Enclosed within this volume is a subset of the marsh ecosystem, which includes submersed plants; algae suspended in the water column, attached to the plant surfaces and burrowing in the soft sediments; numerous swimming and attached invertebrates and several small fish species. These enclosures can be manipulated through controlled additions of chemicals to illustrate how sunlight energy flows from the photosynthesizing algae and plants to the grazing herbivores and ultimately to terrestrial species, such as birds, that depend on aquatic insects and fish for food.

Any project aimed at studying the responses of an entire ecosystem to experimentation is necessarily interdisciplinary, involving collaborators from several disciplines of biology. The current research team consists of Dr. Gordon Goldsborough (Department of Botany, Brandon University) and Dr. Brenda Hann (Department of Zoology), assisted by undergraduate students from the Environmental Science Program and graduate students in Botany and Zoology. Research funding is provided by research grants from the Natural Sciences and Engineering Research Council of Canada, the University Field Station, the University of Manitoba and Brandon University.

Since 1991, several controlled experiments have been carried out using the Delta Marsh enclosure complex. Early experiments involved adding chemical herbicides that block the growth of plants and, thereby, block energy flow to grazing animals. In 1993 and 1994 experiments were conducted using enrichment with nitrogen and phosphorus; two key nutrients found in human and animal wastes and in agricultural fertilizers and that are largely responsible for the greening of prairie lakes and rivers. One interesting response to fertilization was the occurrence of thick floating carpets of algae. Species of invertebrates which use the floating algae to construct protective cases, and which were previously rare in the Delta Marsh, became abundant. This discovery received international media attention, as it indicated that the flora and fauna of polluted marshes may undergo significant changes. Upcoming experiments, to be done in collaboration with the Delta Waterfowl and Wetlands Research Station, will study the role of nutrients provided from ducks and geese that use the marsh as a stopover on their spring and autumn migrations through the area.

Expansion of the enclosure complex is planned to enable the simultaneous manipulation of several factors at once, in order to gain a better appreciation for the interactions that occur between environmental factors in a natural setting. The long-term goal of the project is to establish a large complex of enclosures that can be used for further study of energy flow through the Delta Marsh, so that the impact of environmental changes on this delicate and fundamentally important ecosystem can be predicted.

Five research papers have emanated from work done at the Station in 1994.

Teaching

The following credit courses were presented at the Field Station during 1994:

Vascular Flora of Manitoba Instructor: Maria Zbigniewicz	1.207	June 26 - July 9
Principles of Ecology Instructor: Tom Booth	1.237 / 22.237	July 10 - 23
Community Ecology Instructor: Norm Kenkel	1.354	July 24 - August 6
Field Ecology Instructors: Isobel Waters & Jack Gee	1.342 / 22.345	August 21 - Sept. 2
Landscape Architectural Field Ecology Instructor: Jason Greenall	31.712	August 21 - 26

Schools Program

Outreach activities with schools in Manitoba have again increased in 1994 (by 59% over 1993). I would like to commend the teachers and counselors for the enthusiasm and dedication which bring them and their students to the University Field Station.

New Building

Those who spend any time at the Field Station very quickly realize that the multiple use of Mallard Lodge as classroom, meeting room and library leads to congestion, and there is a clear need for a new classroom/library facility at the Station. This is increasingly obvious as facility use increases. I am happy to report that plans for such a new facility exist, and with the support of Friends of the Field Station, Canada Trust Friends of the Environment Foundation and private donators, it will hopefully be built in the next year.