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Trends in Canadian shorebirds

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Trends in Canadian shorebirds

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C. Gratto-Trevor, R.I.G. Morrison, B. Collins, J. Rausch, M. Drever, and V. JohnstonFootnote[1]

Canadian Biodiversity: Ecosystem Status and Trends 2010
Technical Thematic Report No. 13
Published by the Canadian Councils of Resource Ministers

Library and Archives Canada Cataloguing in Publication

Trends in Canadian shorebirds.

Issued also in French under title:
Tendances relatives aux oiseaux de rivage canadiens.
Electronic monograph in PDF format.
ISBN 978-1-100-20626-4
Cat. no.: En14-43/13-2012E-PDF

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This report should be cited as:
Gratto-Trevor, C., Morrison, R.I.G., Collins, B., Rausch, J., Drever, M. and Johnston, V. 2011. Trends in Canadian shorebirds. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 13. Canadian Councils of Resource Ministers. Ottawa, ON. iv + 32 p.

© Her Majesty the Queen in Right of Canada, 2012
Aussi disponible en français

Footnotes

Footnote 1

All authors are with Environment Canada

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Preface

The Canadian Councils of Resource Ministers developed a Biodiversity Outcomes FrameworkFootnote1in 2006 to focus conservation and restoration actions under the Canadian Biodiversity Strategy.Footnote2Canadian Biodiversity: Ecosystem Status and Trends 2010Footnote3was a first report under this framework. It assesses progress towards the framework’s goal of “Healthy and Diverse Ecosystems” and the two desired conservation outcomes: i) productive, resilient, diverse ecosystems with the capacity to recover and adapt; and ii) damaged ecosystems restored.

The 22 recurring key findings that are presented in Canadian Biodiversity: Ecosystem Status and Trends 2010 emerged from synthesis and analysis of technical reports prepared as part of this project. Over 500 experts participated in the writing and review of these foundation documents. This report, Trends in Canadian shorebirds, is one of several reports prepared on the status and trends of national cross-cutting themes. It has been prepared and reviewed by experts in the field of study and reflects the views of its authors.

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Acknowledgements

We thank the coordinators and hundreds of skilled volunteers in Canada who have participated in the Breeding Bird Survey and migration monitoring programs such as the Atlantic Canada Shorebird Survey, Quebec checklist program, Ontario Shorebird Survey, and the Arctic Program for Regional and International Shorebird Monitoring. Information on trends of migrating shorebirds in British Columbia were based on surveys organized by R. Butler and M. Lemon. We would also like to thank Dr. E. Krebs, Science and Technology Branch, Environment Canada, for her comments on the manuscript.

Ecological Classification System – Ecozones+

A slightly modified version of the Terrestrial Ecozones of Canada, described in the National Ecological Framework for Canada,Footnote4 provided the ecosystem-based units for all reports related to this project. Modifications from the original framework include: adjustments to terrestrial boundaries to reflect improvements from ground-truthing exercises; the combination of three Arctic ecozones into one; the use of two ecoprovinces – Western Interior Basin and Newfoundland Boreal; the addition of nine marine ecosystem-based units; and, the addition of the Great Lakes as a unit. This modified classification system is referred to as “ecozones+” throughout these reports to avoid confusion with the more familiar “ecozones” of the original framework.Footnote5

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Ecological classification framework for the Ecosystem Status and Trends Report for Canada.

map

Long Description for Ecozones+ map of Canada

This map of Canada shows the ecological classification framework for the Ecosystem Status and Trends Report, named “ecozones+”. This map shows the distribution of 15 terrestrial ecozones+, two large lake ecozones+, and nine marine ecozones+.

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Introduction

Canada has a significant responsibility with respect to shorebirds because it contains a considerable proportion of North American breeding habitat (especially in the Arctic) and very important staging sites on the coasts and in the interior of the country. A total of 47 species breed or occur regularly in Canada, and approximately a third of those have more than half of their global breeding range in Canada (Donaldson et al., 2000). Trend data exist from several monitoring schemes. Migration surveys such as the Atlantic Canada Shorebird Survey (ACSS) (Morrison et al., 1994), Ontario Shorebird Survey (OSS) (Ross et al., 2001), and Quebec checklist (Aubry and Cotter, 2007) have provided information on trends in shorebird numbers, particularly for Arctic breeders migrating through the east. The Breeding Bird Survey (BBS) (Sauer et al., 2008) provides trend information for some southern or boreal breeding species, although this roadside singing bird survey is not optimally designed for most shorebirds, particularly those associated with wetlands. It works best for shorebirds such as Killdeer (Charadrius vociferus) and Upland Sandpipers (Bartramia longicauda). Species such as the Piping Plover (Charadrius melodus) have dedicated surveys on the breeding grounds in Canada. Studies in specific arctic areas have shown trends at some sites (for example Rasmussen Basin), and winter surveys in South America have been used to show trends in species such as Red Knot (Calidris canutus). The PRISM (Program for Regional and International Shorebird Monitoring) Arctic Surveys Program (Bart et al., 2005) will eventually provide trend information across the Canadian Arctic. Currently, survey coverage for this group of birds is rather patchy.

This report describes our knowledge of shorebirdFootnote6 trends in Canadian regions with significant shorebird use. Trends of most Canadian shorebirds appear to be negative. Potential causes of declines include: loss and degradation of coastal, wetland, and grassland habitat (during breeding, migration stop-overs, and wintering); climate (such as cooling eastern Arctic, El Nino, and droughts); changes in predator regimes (for example increased predation pressure due to a decrease in trapping of foxes or decline in DDT resulting in an increase in raptors); human disturbance; contaminants; and disease (Donaldson et al., 2000). Declining trends in shorebird numbers are of particular concern because shorebird populations are often slow to recover owing to their relatively low reproductive rate (small clutch size of four eggs, little renesting (especially in the Arctic), and usually delayed age of first breeding), longevity, and often low global population numbers. In addition, shorebirds are thought to be highly vulnerable to climate change because most are dependent on shallow water habitats for foraging during breeding, migratory staging, and wintering, and many breed in the Arctic where climate change is expected to be most extreme. Many species undergo long migrations between Arctic breeding and South American wintering sites and must time migrations to coincide with peak invertebrate productivity and/or availability at staging sites in order to acquire enough resources for their long over-water nonstop flights. The habit of many species to flock in large numbers at specific staging and wintering sites can make a large percentage of the population vulnerable to catastrophic events such as oil spills or storms, and their intertidal foraging habitat is vulnerable to rising sea levels and development.

Footnotes

Footnote 1

Environment Canada. 2006. Biodiversity outcomes framework for Canada. Canadian Councils of Resource Ministers. Ottawa, ON. 8 p.

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Footnote 2

Federal-Provincial-Territorial Biodiversity Working Group. 1995. Canadian biodiversity strategy: Canada's response to the Convention on Biological Diversity. Environment Canada, Biodiversity Convention Office. Ottawa, ON. 86 p.

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Footnote 3

Federal, Provincial and Territorial Governments of Canada. 2010. Canadian biodiversity: ecosystem status and trends 2010. Canadian Councils of Resource Ministers. Ottawa, ON. vi + 142 p.

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Footnote 4

Ecological Stratification Working Group. 1995. A national ecological framework for Canada. Agriculture and Agri-Food Canada, Research Branch, Centre for Land and Biological Resources Research and Environment Canada, State of the Environment Directorate, Ecozone Analysis Branch. Ottawa/Hull, ON. 125 p. Report and national map at 1:7 500 000 scale.

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Footnote 5

Rankin, R., Austin, M. and Rice, J. 2011. Ecological classification system for the ecosystem status and trends report. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 1. Canadian Councils of Resource Ministers. Ottawa, ON.

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Footnote 6

A list of common and latin names for shorebirds discussed in this report is provided in Appendix 1

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Introduction