Population status

Great Blue Heron
(Ardea herodias)

The Breeding Bird Survey (BBS) provides the best long-term national-scale picture of Great Blue Heron trends, and suggests a decrease of about 31% in the Canadian population since about 1970. These BBS results have high precision and provide good coverage of the breeding population for this easily recognized species. BBS results vary among the various Bird Conservation Regions that host the species and for which there are reasonably reliable results (displayed below). Results from the Great Lakes Decadal Colonial Waterbird Census and the British Columbia Coastal Waterbird Survey support an ongoing decline in abundance since the early/mid-1990s supporting the BBS results in those regions. Some smaller trend estimates are contradictory among neighbouring regions (e.g., Vennesland and Butler 2011).

Breeding Bird Survey (BBS) - Canadian analysis

Additional information on: Breeding Bird Survey (BBS) - Canadian analysis

View definitions of table column headings being used by: Breeding Bird Survey (BBS) - Canadian analysis

Table 1: Population trends by geographic area
Geographic area	Time Period ^{Table 1 - footnote 1}	Annual trend ^{Table 1 - footnote 2}	Intervals ^{Table 1 - footnote3}
Geographic area	Time Period ^{Table 1 - footnote 1}	Annual trend ^{Table 1 - footnote 2}	Lower	Upper
Canada Select to view graph of the geographic area: Canada 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis	1970-2012	-0.9	-1.7	-0.1
Northern Pacific Rainforest Select to view graph of the geographic area: Northern Pacific Rainforest 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis	1970-2012	-3	-5	-1
Boreal Taiga Plains Select to view graph of the geographic area: Boreal Taiga Plains 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis	1970-2012	0.9	-1	3.3
Great Basin Select to view graph of the geographic area: Great Basin 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis	1970-2012	2.6	-0.1	5.5
Prairie Potholes Select to view graph of the geographic area: Prairie Potholes 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis	1970-2012	-1.1	-2.8	0.6
Boreal Hardwood Transition	1970-2012	-0.9	-1.7	0.1
Lower Great Lakes / St. Lawrence Plain Select to view graph of the geographic area: Lower Great Lakes / St. Lawrence Plain 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis	1970-2012	-1	-2	0
Atlantic Northern Forest Select to view graph of the geographic area: Atlantic Northern Forest 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis	1970-2012	-1.2	-2.5	0.1
Canada Select to view graph of the geographic area: Canada 2002-2012; Breeding Bird Survey (BBS) - Canadian analysis	2002-2012	-0.1	-1.8	1.9
Northern Rockies	2002-2012	2.3	-2.8	9

Great Lakes Decadal Colonial Waterbird Census

View numerical data of the graph.

British Columbia Coastal Waterbird Survey

Additional information on: British Columbia Coastal Waterbird Survey

Assessment date: 2011

View definitions of table column headings being used by: British Columbia Coastal Waterbird Survey

Table 2: Population trends by geographic area
Geographic area	Time Period	Annual trend ^{Table 2 - footnote 1}	Limits
Geographic area	Time Period	Annual trend ^{Table 2 - footnote 1}	Lower	Upper
Straight of Georgia Select to view graph of the geographic area: Straight of Georgia 1999-2011; British Columbia Coastal Waterbird Survey	1999-2011	-2.9	-4.7	-1.2

References

COSEWIC. 2008g. COSEWIC Assessment and Update Status Report on the Great Blue Heron fannini subspecies Ardea herodias fannini in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 39 pp. COSEWIC. 2008g. COSEWIC Assessment and Update Status Report on the Great Blue Heron fannini subspecies Ardea herodias fannini in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 39 pp. (Link)
Naylor, B. 2007. Great Blue Heron. pp. 158-159 in: Atlas of the Breeding Birds of Ontario, 2001-2005. Cadman, M.D., D.A. Sutherland, G.G. Beck, D. Lepage and A.R. Couturier, Eds. Bird Studies Canada, Environment Canada, Ontario Field Ornithologists, Ontario Ministry of Natural Resources, and Ontario Nature, Toronto, Ontario.
Vennesland, R. and R.W. Butler. 2011. Great Blue Heron (Ardea herodias), The Birds of North America Online (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York. Vennesland, R. and R.W. Butler. 2011. Great Blue Heron (Ardea herodias), The Birds of North America Online (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York. (Link)