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Evening Grosbeak - Coccothraustes vespertinus
Species of Concern Native Species Global Rank :
G5
State Rank :
S3
(see State Rank Reason below)
Agency Status USFWS :
MBTA; BCC10
USFS :
BLM :
FWP SWAP :
SGCN3
PIF :
External Links
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Copyright by: The Macaulay Library at the Cornell Lab of Ornithology, Ithaca, NY, all rights reserved.
State Rank Reason (see State Rank above)
Populations in Montana and across North America have experienced rangewide declines, although the causes of these declines are unclear (Bonter and Harvey 2008).
Details on Status Ranking and Review
Evening Grosbeak (Coccothraustes vespertinus ) Conservation Status Review
Population Size
Score U - Unknown
Comment Unknown.
Range Extent
Score F - 20,000-200,000 km squared (about 8,000-80,000 square miles)
Comment 174,759 square kilometers based on Natural Heritage Program range maps that appear on the Montana Field Guide.
Area of Occupancy
Score U - Unknown
Comment Unknown.
Long-term Trend
Score E - Relatively Stable (±25% change)
Comment Conifer forest and mixed conifer forest habitats relatively stable within +/-25% since European arrival.
Short-term Trend
Score C - Rapidly Declining. Decline of 30-50% in population, range, area occupied, and/or number or condition of occurrences
Comment BBS data has moderate credibility with a significant decline of -10.7% per year or 68% decrease per decade. For the entire Northern Rockies with highest credibility there is a significant decline of -6.9% per year or 51% decline per decade. Declines also noted with Christmas Bird Count data and Project Feeder Watch.
Threats
Score U - Unknown. The available information is not sufficient to assign degree of threat as above. (Severity, scope, and immediacy are all unknown, or mostly [two of three] unknown or not assessed [null].)
Comment No operational threats identified.
Severity Unknown - Unknown
Comment No operational threat identified.
Scope Unknown - Unknown
Comment No operational threat identified.
Immediacy Unknown - Unknown
Comment No operational threat identified.
Intrinsic Vulnerability
Score C - Not Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance; or species has high dispersal capability such that extirpated populations soon become reestablished through natural recolonization (unaided by humans).
Comment Not Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has a high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance. Species has good dispersal capabilities such that extirpated populations generally become reestablished through natural recolonization.
Environmental Specificity
Score C - Moderate. Generalist. Broad-scale or diverse (general) habitat(s) or other abiotic and/or biotic factors are used or required by the species but some key requirements are scarce in the generalized range of the species within the area of interest.
Comment Moderate Generalist. Generalist in conifer and mixed conifer forests.
Raw Conservation Status Score
Score
3.5 + 0.0 (geographic distribution) + 0.0 (environmental specificity) - 0.5 (short-term trend) + 0.0 (threats) = 3
General Description
The Evening Grosbeak is a large, robust finch with a massive, conical bill. This species forms large, irruptive feeding flocks in winter, announcing its arrival with a loud "
clee-ip " or "
peeer " call. Although gregarious in winter, this species is secretive during the breeding season and little is known about its breeding biology (Gillihan and Byers 2001).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see
Marks et al. 2016, Birds of Montana. Phenology
Adults observed feeding young from late-May through August. Feeding flocks are irruptive and have been observed September-early May, with the largest flock size occurring during the winter months of December-February (Montana Natural Heritage Program Point Observation Database 2014).
Diagnostic Characteristics
A large, stocky finch with a heavy, greenish-yellow bill. Adult male has a brownish-black head with a black crown, and a yellow forehead and eyebrow. The neck and back are brown contrasting with yellow shoulders and rump. Tail and wings are black with large white patches. Throat is brown and underparts are brownish-yellow. Adult female is mostly grayish brown with a thin moustache and yellowish wash on the sides of the neck. Wings and tail are black with white spotting. Throat and underparts are pale grayish-brown. Juvenile resembles adult female (Gillihan and Byers 2001).
Species Range
Montana Range
Range Descriptions Western Hemisphere Range
Range Comments
In Montana, the Evening Grosbeak breeds in coniferous forests of western Montana. In fall and winter, this species is irruptive and is much more widespread, occurring throughout the state.
Observations in Montana Natural Heritage Program Database
Number of Observations: 11113
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
Relative Density
Recency
SUMMER (Feb 16 - Dec 14)
Direct Evidence of Breeding
Indirect Evidence of Breeding
No Evidence of Breeding
WINTER (Dec 15 - Feb 15)
Regularly Observed
Not Regularly Observed
(Observations spanning multiple months or years are excluded from time charts)
Migration
This species has been observed in feeding flocks from September to early May. Spring movements to higher elevation breeding habitat occur in mid- to late-May, with fall movements beginning in early September (Montana Natural Heritage Program Point Observation Database 2014).
Habitat
In Montana, the Evening Grosbeak breeds in mixed coniferous and spruce-fir forests of western Montana. Winter habitat is much more varied, including coniferous forest as well as urban and suburban areas statewide (Gillihan and Byers 2001, Montana Natural Heritage Program Point Observation Database 2014).
Ecological Systems Associated with this Species
Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system,
even if point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at:
mtnhp.org/requests ) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
Literature Cited
Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
Commonly Associated with these Ecological SystemsForest and Woodland Systems
Human Land Use
Recently Disturbed or Modified
Shrubland, Steppe and Savanna Systems
Wetland and Riparian Systems
Occasionally Associated with these Ecological SystemsForest and Woodland Systems
Grassland Systems
Shrubland, Steppe and Savanna Systems
Food Habits
This species feeds upon invertebrates, especially larvae, and a wide variety of seeds and fruits. Forages in the tops and outer branches of trees and shrubs, and also on the ground for fallen fruits and seeds. This species is a frequent visitor to bird feeders, particularly during fall and winter (Gillihan and Byers 2001).
Ecology
Winter flocks can number in the hundreds during irruptions (Gillihan and Byers 2001). However, this species becomes quite secretive during the breeding season, and relatively little is known of its life history. This species loud, rather unmusical call is unmistakable, and it is given year round. In fact, the Evening Grosbeak's repertoire is made up of a series of calls, trills, and chatters, but this species apparently rarely, if ever, sings.
Reproductive Characteristics
Large winter flocks break up into smaller groups about 3-4 weeks before breeding begins. Pair formation occurs during this time, and birds arrive on breeding grounds as mated pairs. Females begin nest construction immediately after arrival on the breeding grounds. Nests are placed primarily in the upper portion of coniferous trees, often near the trunk. The nest is a spare, saucer-shaped structure composed of small twigs and roots and lined with grasses, lichens, and pine needles. Clutch size averages 3-4 eggs; female incubates. Incubation period ranges from 12-14 days. Female broods nestlings. Both adults feed nestlings, although female feeds more frequently. Nestling period is 13-14 days. Both adults feed fledged young up to several weeks after fledging (Gillihan and Byers 2001).
Management
Several studies suggest that the Evening Grosbeak is more abundant in mature forests with high structural diversity (Bonter and Harvey 2008). This species is often killed in collisions with residential windows, likely due to their presence at feeders during the winter (Gillihan and Byers 2001).
Threats or Limiting Factors
Loss of mature, structurally diverse coniferous forests can impact breeding habitat for this species. Additionally, the Evening Grosbeak is susceptible to a number of diseases including bacterial conjunctivitis, salmonellosis, and West Nile virus. There is some evidence that Evening Grosbeak populations may fluctuate with spruce budworm cycles, but this link is unclear (Bonter and Harvey 2008).
References
Literature Cited AboveLegend:
Additional ReferencesLegend: Do you know of a citation we're missing? Effects of recreation on Rocky Mountain wildlife: a review for Montana . [Montana]: Montana Chapter of the Wildlife Society.
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