- The Rusty Blackbird has a northern breeding range, where it is mainly found in wet coniferous forests (mainly black spruce and tamarack) near and along bogs, muskeg swamps, beaver ponds, and streams.1
- Nests are usually built in dense thickets of small conifers (e.g., 3–6 m black spruce with <8 cm dbh or 1–3 m balsam fir) or, where coniferous trees are limiting, deciduous shrubs (e.g., willow).2,3
- Nests are typically built within 12 m of water, on average.3
- Important habitat features for nest sites include shallow or vernal pools containing aquatic invertebrates and insects4 (including recently burned wetlands5).
- Stand age appears to be less important than the presence of short conifers, whether due to recent disturbance (e.g., harvest) or due to stunted growth on wet/low-productivity sites.6
Response to Forest Management
- Harvest effects in western forests are poorly understood for Rusty Blackbirds. While they have been observed in harvested stands containing residuals up to 30 years postharvest, sample sizes have been too low to conclusively infer a positive response to harvesting.7–9
- Some studies of reproductive success in New England suggest that harvested stands near coniferous wetlands may act as ecological traps, however results have been mixed and local studies are needed.
- In one study, Rusty Blackbirds preferentially nested in <20 year-old regenerating clearcuts than in unharvested stands. However, nests in harvested stands were less than half as likely to successfully fledge young than nests in unharvested areas.3
- In another study in the same region found that harvest history did not affect nest success, but rather that survival increased with increasing densities of trees ≤4 cm dbh around nests.10
- Continuous, 75 m buffers are recommended around coniferous bogs, fens, and other wetlands suitable for Rusty Blackbirds.
- These buffers should provide nesting habitat and increase nest survival.3,11
- Voluntary buffering of, or retention patches anchored around, small or vernal pools is recommended, particularly if the surrounding vegetation contains short, small-diameter, dense conifers (black spruce, tamarack, or balsam fir).1,10
- Precommercial thinning of small-diameter conifers is discouraged in cutblocks adjacent to coniferous wetlands or streams, as the reduced cover will make Rusty Blackbird nests more vulnerable to predators.10
- The Rusty Blackbird’s primary breeding habitats are likely to be well-represented on the passive landbase, including shallow wetlands, bogs, muskeg, beaver ponds, and low-productivity wet coniferous stands. Areas with high proportions of these features within a 38-ha area (i.e., this species’ home range) are considered of highest value and, if possible, road-building and other disturbances should be avoided within them.10
- While there is some evidence that Rusty Blackbirds are drawn to harvest-origin early-seral habitats with dense regenerating conifers, research is needed in western forests to determine whether these habitats negatively impact nest success.3,10