Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The global population is estimated to number > c.3,000,000 individuals (Rich et al. 2004). The European population is estimated at 1,080,000-2,110,000 pairs, which equates to 2,160,000-4,220,000 mature individuals (BirdLife International 2015). Europe forms c.15% of the global range, so a very preliminary estimate of the global population size is 14,400,000-28,150,000 mature individuals, although further validation of this estimate is needed.
This species has undergone a small or statistically insignificant decrease over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007). In Europe the overall trend from 1980-2013 was strongly increasing (EBCC 2015).
The species breeds in boreal forest and muskeg. It prefers relatively open forest or edge, usually coniferous e.g. spruce (Picea), pine (Pinus) and occasionally birch (Betula) forest or mixed forest. It prefers well-drained areas near major rivers, normally including dense growth of fruiting plants. In non-breeding season it is found in a wide variety of habitats with fruiting plants and at least scattered trees, including roadsides, gardens, farmland and the edges of deciduous forest. The breeding season is relatively late with egg-laying beginning in late May. The nest is an open cup of fine twigs and coarse grasses, lined with finer material including grasses, mosses, plant fibres and feathers or mammal fur and usually placed on the horizontal branch of a tree, often close to trunk. Clutches are from three to seven eggs. Its diet is predominantly fruits and insects but also includes buds of various trees, flowers, tree sap, bark, shoots and leaves, moss and lichens, spiders, snails, and varied table scraps from feeders. The species is a partial migrant, withdrawing from a large portion of its breeding range in winter (Mountjoy 2005).
Collisions with windows and ingestion of road salt have been suggested as threats to this species (Töpfer 2010). The breeding range is generally to the north of dense human populations and the species is known to use disturbed habitats, therefore populations are not likely to suffer significant declines in the near future (Mountjoy 2005).
Conservation Actions Underway
Bern Convention Appendix II. There are currently no known conservation measures for this species within Europe.
Conservation Actions Planned
Although this species is not threatened, research into the impact of road salt poisoning may inform future conservation measures (Töpfer 2010).
Text account compilers
Butchart, S., Ekstrom, J., Symes, A., Ashpole, J
BirdLife International (2017) Species factsheet: Bombycilla garrulus. Downloaded from http://www.birdlife.org on 17/10/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/10/2017.