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Bird Habitat Conservation Toolkit

Image of Bird
A striking bird with a striking song. Listen for “see-see-see-see-see-SooZIE” in pure or mixed white spruce stands.

Black-throated Green Warbler

(Setophaga virens)
Overview
status
AlbertaSensitive
British ColumbiaBlue
Primary Habitat
Old coniferous/mixedwood
Nest Type
Canopy (conifer)
Territory Size
0.12 - 1 ha
Nest Reuse
No
Breeding Window
Jan
Feb
Mar
Apr
May
Jun
Jun
Jul
Aug
Sep
Sep
Oct
Nov
Dec
Peak: mid-June to late August
Stand-Level
High dispersed retention or >0.5 ha patches of large-diameter Sw, Bw
Landscape-Level
Old (100–130 years) riparian Sw or mixedwood, >100 ha if possible

Habitat Ecology

  • Black-throated Green Warblers are found in a wide range of forests containinglarge white spruce (including mixedwoods and deciduous-leading forests), with their highest densities in 100–130 year stands where they often use small-scale canopy gaps.1,2 They are also known to occupy young to mature forests.3,4
  • In BC, mature riparian white spruce or mixedwood forests are considered their most important habitat, while mature or old deciduous forests containing mature spruce may attract them.3
  • These warblers forage and nest on large-diameter (>50 cm dbh) white spruce.1
  • Black-throated Green Warblers usually nest in conifers5 but have shown some preference for paper birch with ~20 cm dbh in Alberta.1

Response to Forest Management

  • This species is most abundant on unlogged landscapes6 with a strong preference for forests exceeding the rotation age.7
  • In deciduous-dominated forests in Alberta, they disappeared from stands with 2–6% retention but were present at low levels in harvests with 40% retention.⁸ They were unlikely to be present in clearcut (i.e. no planned retention) stands up to 33 years postharvest.9
  • They may be sensitive to fragmentation: in New England, they were absent from forests <100 ha,5 and there is evidence that they avoid cutblock edges and crossing openings ≥25–40 m wide.2,10

Stand-level Recommendations

  • High retention (>40%) may be needed to reduce short-term harvest effects on this species, however these recommendations are based on studies from aspen-leading boreal mixedwood forests and may not be applicable to spruce-leading or -dominated forests.11,12
  • Retention patches placed ≤40 m apart may make it easier for these warblers to travel across large harvest areas, however this strategy has not been tested for efficacy.
  • Mixed-species retention patches (0.5 ha) containing large-diameter spruce may provide suitable nesting habitat in 30–60 years within a harvest block.2
  • Riparian buffers >20 m may support pairs, but larger (>60 m) buffers will likely be more effective.13

Landscape-level Recommendations

  • Mixedwood management to maintain coniferous-deciduous mixed stands on the landscape, as is present under NRV scenarios, will benefit this species.
  • Old (100–130 year-old) mixed and spruce-leading stands >100 ha will provide important habitat on intensively-managed landscapes, as retention patches are expected to take several decades to provide suitable breeding habitat.2
  • The role of older-than-rotation stands will likely be most important in BC, where its range is extremely limited and riparian spruce or mixed forests are highly valuable.3

References

  1. Alberta Environment and Sustainable Resource Development. 2014. Black-Throated Green Warbler, Bay-Breasted Warbler and Cape May Warbler Conservation Management Plan 2014-2019. Alberta Environment and Sustainable Resource Development. Species at Risk Conservation Management Plan No. 10, Edmonton, AB. 33 pp.
  2. Norton, M. R. 1999. Status of the Black-throated Green Warbler (Dendroica virens) in Alberta: Alberta wildlife status report no. 23. Alberta Environment, Fisheries and Wildlife Management Division, and Alberta Conservation Association, Wildlife Status Report No. 23, Edmonton, AB. 24 pp. Available online: http://www.gov.ab.ca/env/fw/status/reports/index.htm
  3. Cooper, J. M., Enns, K. A. & Shepard, M. G. 1997. Status of the Black-throated green warbler in British Columbia. Wildlife Working Report No. WR-80 British Columbia Ministry of Environment, Lands and Parks, Wildlife Working Report No. WR-80, Victoria, B.C. 38 pp.
  4. Boreal Avian Modelling Project. 2012. Black-throated Green Warbler: Relative Density by Habitat. Available online: http://www.borealbirds.ca/avian_db/accounts.php/Setophaga+virens/habitat
  5. Morse, D. H. & Poole, A. F. 2005. Black-throated Green Warbler (Setophaga virens), version 2.0. in The Birds of North America (Rodewald, P. G., ed.) Cornell Lab of Ornithology, Ithaca, New York, USA. Available online: https://doi.org/10.2173/bna.55
  6. Venier, L. A. & Pearce, J. L. 2007. Boreal forest landbirds in relation to forest composition, structure, and landscape: implications for forest management. Canadian Journal of Forest Research 37: 1214–1226.
  7. Schieck, J. & Song, S. J. 2006. Changes in bird communities throughout succession following fire and harvest in boreal forests of western North America: literature review and meta-analyses. Canadian Journal of Forest Research 36: 1299–1318. Available online: https://doi.org/10.1139/x06-017
  8. Schieck, J., Stuart-Smith, K. & Norton, M. 2000. Bird communities are affected by amount and dispersion of vegetation retained in mixedwood boreal forest harvest areas. Forest Ecology and Management 126: 239–254.
  9. Leston, L., Bayne, E. & Schmiegelow, F. 2018. Long-term changes in boreal forest occupancy within regenerating harvest units. Forest Ecology and Management 421: 40–53. Available online: https://doi.org/10.1016/j.foreco.2018.02.029
  10. Rail, J.-F., Darveau, M., Desrochers, A. & Huot, J. 1997. Territorial responses of boreal forest birds to habitat gaps. The Condor 99: 976–980. Available online: http://www.jstor.org/stable/1370150
  11. Tittler, R., Hannon, S. J. & Norton, M. R. 2001. Residual tree retention ameliorates short-term effects of clear-cutting on some boreal songbirds. Ecological Applications 11: 1656–1666.
  12. Norton, M. R. & Hannon, S. J. 1997. Songbird response to partial-cut logging in the boreal mixedwood forest of Alberta. Canadian Journal of Forest Research 27: 44–53. Available online: http://www.nrcresearchpress.com/doi/abs/10.1139/x96-149
  13. Darveau, M., Beauchesne, P., Bélanger, L., Huot, J. & Larue, P. 1995. Riparian forest strips as habitat for breeding birds in boreal forest. The Journal of Wildlife Management 59: 67–78. Available online: http://www.jstor.org/stable/3809117

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