Population status

Gadwall
(Mareca strepera)

The Gadwall is primarily monitored in its core breeding area through the Waterfowl Breeding Population and Habitat Survey in western Canada, as well as the Waterfowl Breeding Population Survey of the Central Interior Plateau of British Columbia. The Gadwall popuation in Canada has shown a large increase since the early 1990s, following a period of prolonged drought in the 1980s. Gadwall populations are above their North American Waterfowl Management Plan goal in most surveyed areas (North American Waterfowl Management Plan 2012) and the population size in the traditional survey area is more than twice the objective of 1.5 million birds. The species is at an acceptable level relative to its national population goal. Detailed information on the population status of waterfowl species is available in the Population Status of Migratory Game Birds in Canada report (summarized version). To obtain a copy of the full version of this report, including tables and graphs, please contact ec.scf-oismiggibiers-cws-miggamebirds.ec@canada.ca.

Population goal and acceptable levels of variation

Species/group	Goal	Lower level	Upper level
Canada	Long-term average of the time series	10th percentile of observed abundance (1970-2012)	Not applicable

British Columbia Coastal Waterbird Survey

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Table 1: Population trends by geographic area
Geographic area	Time Period	Annual Trend ^{Table 1 - footnote 1}	Limits
Geographic area	Time Period	Annual Trend ^{Table 1 - footnote 1}	Lower	Upper
British Columbia coast	1999-2016	-6.6	-13.9	2.6

Waterfowl Breeding Population and Habitat Survey in Western Canada and the Northwestern United-States

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Table 2: Population trends by geographic area
Geographic area	Time Period	Annual trend ^{Table 2 - footnote 1} ^{Table 2 - footnote 2}	Limits
Geographic area	Time Period		Lower	Upper
Total survey area Select to view graph of the geographic area: Total survey area 1955-2017; Waterfowl Breeding Population and Habitat Survey in Western Canada and the Northwestern United-States	1955-2017	3.1	2.8	3.4
Canadian Prairies Select to view graph of the geographic area: Canadian Prairies 1955-2017; Waterfowl Breeding Population and Habitat Survey in Western Canada and the Northwestern United-States	1955-2017	2.9	2.6	3.3
Western Boreal Forest Select to view graph of the geographic area: Western Boreal Forest 1955-2017; Waterfowl Breeding Population and Habitat Survey in Western Canada and the Northwestern United-States	1955-2017	0.5	-0.4	1.2

Cooperative Yukon roadside Waterfowl Breeding Population Survey

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Table 3: Population trends by geographic area
Geographic area	Time Period	Annual trend ^{Table 3 - footnote 1} ^{Table 3 - footnote 2}	Limits
Geographic area	Time Period		Lower	Upper
Southern Yukon Select to view graph of the geographic area: Southern Yukon 1991-2016; Cooperative Yukon roadside Waterfowl Breeding Population Survey	1991-2016	0.6	0	0.3

Waterfowl Breeding Population Survey of the Central Interior Plateau of B.C.

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Table 4: Population trends by geographic area
Geographic area	Time Period	Annual trend ^{Table 4 - footnote 1} ^{Table 4 - footnote 2}	Limits
Geographic area	Time Period		Lower	Upper
British -Columbia Central Plateau	2006-2017	-3	-9.5	2.8

References

Baldassarre, G. 2014. Ducks, Geese, and Swans of North America. Volume 2. Wildlife Management Institute, Johns Hopkins University Press, Washington, D.C. 1027 pp.
Canadian Wildlife Service (CWS) Waterfowl Committee. 2017. Population Status of Migratory Game Birds in Canada: November 2017. CWS Migratory Birds Regulatory Report Number 49. 221 pp. Canadian Wildlife Service (CWS) Waterfowl Committee. 2017. Population Status of Migratory Game Birds in Canada: November 2017. CWS Migratory Birds Regulatory Report Number 49. 221 pp. (Link)
Leschack, C.R., S.K. McKnight, and G.R. Hepp. 1997. Gadwall (Mareca strepera), version 2.0. In: The Birds of North America (P.G. Rodewald, ed.). Cornell Lab of Ornithology, Ithaca, New York, USA. Leschack, C.R., S.K. McKnight, and G.R. Hepp. 1997. Gadwall (Mareca strepera), version 2.0. In: The Birds of North America (P.G. Rodewald, ed.). Cornell Lab of Ornithology, Ithaca, New York, USA. (Link)
North American Waterfowl Management Plan. 2012. North American Waterfowl Management Plan 2012: People Conserving Waterfowl and Wetlands. Canadian Wildlife Service, U.S. Fish and Wildlife Service, and Secretaria de Medio Ambiente y Recursos Naturales. xii + 48 pp. North American Waterfowl Management Plan. 2012. North American Waterfowl Management Plan 2012: People Conserving Waterfowl and Wetlands. Canadian Wildlife Service, U.S. Fish and Wildlife Service, and Secretaria de Medio Ambiente y Recursos Naturales. xii + 48 pp. (Link)