Euphagus carolinus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Icteridae

Scientific Name: Euphagus carolinus (Müller, 1776)
Common Name(s):
English Rusty Blackbird
Taxonomic Source(s): Cramp, S. and Simmons, K.E.L. (eds). 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Identification information: A medium-sized blackbird with a square-tipped tail and thick bill. Males are entirely black, faintly glossed greenish. The eye is yellow. Females are dark grey-black and lack the glossy sheen of males. Immature birds are brown with a paler supercilium, darker wings and tail and some dark barring on males. Similar spp. very similar to Brewer's Blackbird Euphagus cyanocephalus, but males of that species have a blue body gloss with contrasting violet head and females are browner. Also structurally, rusty blackbird has a finer bill and less elegant gait. Voice Males sing a squeaky but sweet rising kush-a-lee.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2cde+3cde+4cde ver 3.1
Year Published: 2017
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Butcher, G., Greenberg, R., Wells, J., Luepold, S. & McClure, C.
Facilitator/Compiler(s): Bird, J., Butchart, S., Derhé, M., Ekstrom, J., Westrip, J.
This species has experienced a long term population decline which has been rapid during the past decade. For this reason it is currently classified as Vulnerable. More accurate survey data may warrant a re-evaluation of its status.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Euphagus carolinus has a large range, breeding across the boreal zone of North America from New England, through Canada to Alaska and winters widely across the south-eastern United States. The population was estimated at 2 million individuals based on data from the North American Breeding Bird Survey collected during the 1980s and 1990s. This figure is now likely to be a considerable overestimate as the species continues to decline, and a recent study only found the species at <10% of sites (Scarl 2013). Estimates of the global decline since 1966 vary between 85% and 99%. This ongoing decline follows a longer term decline that began prior to 1950. The reasons for this dramatic decline remain poorly understood.

Countries occurrence:
Canada; Saint Pierre and Miquelon; United States
Greenland; Mexico; Russian Federation (Eastern Asian Russia)
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:3790000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The population is estimated to number anywhere between 0.2-2 million individuals (R. Greenberg in litt. 2006).

Trend Justification:  Two sources provide quantitative estimates of decline for the species: Breeding Bird Survey (BBS) and Christmas Bird Counts (CBC). Sauer et al. (2005) provide an estimate for annual declines for a 39 year period of 12.5% per year, derived from BBS data. The estimated trend for the period 1996-2005 is a 1.8% decline per year, equating to a 16.6% decline over ten years. The CBC returns an estimated global decline for this period of 5.1% per year (CI = 2.4- 6.7%) which corresponds to a decline of 40.8% over the past decade. Interpreting the two estimates, the population is believed to have declined by >30% over the past ten years (R. Greenberg in litt. 2006). Butcher and Niven (2007) also combined data from the two sources, estimating a large and statistically significant population decrease over the last 40 years in North America (83.8% decline over 40 years, equating to a 36.6% decline per decade).
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:It breeds in boreal wetlands, primarily around ponds and streams within the boreal forest (see Powell et al. 2014). It winters primarily in wooded wetlands and is not strongly associated with open agricultural habitats.

Systems:Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):4.2
Movement patterns:Full Migrant

Threats [top]

Major Threat(s): The reasons behind current trends are poorly understood but several threats are suspected to be causing the declines. The destruction and conversion of boreal wetlands (predominantly in the southern boreal forests) is a significant threat to the species. Strip-mining for tar sands is expected to increase in the future, with up to 300,000 ha of Canada's boreal forest and wetland predicted to be directly affected over the next 30 to 50 years (Wells et al. 2008). Other possible threats include boreal wetland drying and chemical change resulting from global climate change (Matsuoka et al. 2010, McClure et al. 2012), depletion of available calcium resulting from acid precipitation (Greenberg and Droege 1999, Greenberg et al. 2011), increase in methyl mercury (Greenberg et al. 2011, Edmonds et al. 2012), disease (Barnard et al. 2010), loss of boreal forest habitat due to hydropower development (S. Luepold in litt. 2016), loss of wooded wetlands in the south-east U.S. winter range (Hamel et al. 2009, Greenberg et al. 2011), mortality associated with past and ongoing blackbird control efforts (Greenberg et al. 2011), and potential low level mortality as a result of collisions with communication towers (Longcore et al. 2013).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
The species is not currently listed under the United States Endangered Species Act, but it is listed as a "Species of Special Concern" or "Threatened" or "Endangered" in several states (S. Luepold in litt. 2016). There is an International Rusty Blackbird Technical Group set up to research trends, threats and actions for this species.

Conservation Actions Proposed
Continue to monitor population trends. Identify the reasons behind long-term declines. Devise suitable actions to reverse declines. Consider listing under US Endangered Species Act. Protect suitable habitat.

Amended [top]

Amended reason: Edited the text of Geographic Range, Threats, Conservation Actions and Habitats and Ecology Information. This resulted in the addition of extra references and the species being listed with an additional threat. A spelling mistake in the Additional Details regarding Systematic Monitoring Scheme as a Conservation Action Underway was corrected. Also new Contributors and Facilitator/Compiler were added.

Citation: BirdLife International. 2017. Euphagus carolinus (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T22724329A110058484. . Downloaded on 19 September 2018.
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