Invasive Species Pulling Project: Pale & Black Swallow-wort


The RBA conservation committee has asked birders to patrol local birding trails for Pale & Black Swallow-wort, and hand-pull plants whenever possible. Read below, and print out the attached Factsheet (RBAswallowwortbrochure) and Photo Card (swwcard).




Black and pale swallow-worts, also known as “dog-strangling vines,” are perennial, herbaceous vines that grow from 2 to 6 1/2 ft in length. Native to Eurasia, these species are adapted to a variety of habitats where they out compete native species.

  • Both species of swallow-worts can be found in mixed hardwood forest to heavily shaded woods.
  • They also can be found in disturbed sunny areas, open fields, and along roadsides in moist or dry soils.
  • Twining, vine-like perennial
  • Reproduces by seed and axillary tillers from root crown if main stem is damaged.


  • Crowds out habitat for ground-nesting birds in field and woodland settings
  • Supplants native vegetationfood sources for birds
  • May restrict access to infested areas due to extensive twining
  • Grazers tend to avoid swallow-wort because it is not as palatable as other plant species
  • Pure stands of swallow-wort suppress the establishment of other species and interfere with forest regeneration.

Related to milkweeds, swallow-worts are toxic to livestock, deer and monarch butterfly larvae, which are sometimes fooled into laying their eggs on these plants, but their larvae do not survive.


Bring recycled plastic bags in your birding kit and pull when you find swallow wort. Throw bags in trash, Cook bags in sun first. Do not compost or put out with plant material for the town to collect, seeds can live 4-5 years!

Thanks, the RBA Conservation Committee