Justification of Red List Category
Although this species has a small range, it is thought to be stable 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 stable, 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 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 population is estimated at 4,100-11,400 pairs, which equates to 8,200-22,800 mature individuals (BirdLife International 2015).
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
This species occurs in Scotland, UK, where it is mainly restricted to the eastern Highlands within which core areas are Nairn, Moray and Banff, extending down into lower Deeside, and in Sutherland (Summers and Buckland in press). It is likely that there are shifts in the distribution of the population in response to regional fluctuations in the cone crops of conifers, particularly those of Scots pine Pinus sylvestris (Tucker and Heath 1994, I. Bainbridge and R. Summers in litt. 1999). The population size was estimated at 1,500 adult birds in the early 1970s and at estimate of 300-1250 pairs in 1988. Surveys during 1995-2003 using an apparently diagnostic excitement call to locate the species found it in 94 woods during the breeding season (Summers et al. 2004), but as birds are likely to move seasonally and this study was carried out over several years it is hard to be sure how much duplication is involved. Using the same diagnostic excitement call, a recent study has estimated its population to number 13,600 post-juvenile individuals (Summers and Buckland in press).
This species breeds in lowland forests and stands of Scots pine (Pinus sylvestris), including open mature plantations and ancient relict forest trees. During the winter it is mostly found in larches (Larix) and in established plantations of lodgepole pine (Pinus contorta) and sitka spruce (Picea sitchensis) as well as well-spaced pine woodland with heather (Calluna) understorey. Breeding occurs from January or February to June and the species is monogamous, although occasional polygamy is recorded. The nest is a large bulky cup of twigs (mostly pine, larch or birch), heather, grass, plant fibres, bark strips, moss, lichens, animal hair, leaves and feathers. It is sited six to eight metres above the ground in the upper level of old Scots pine, usually high in the crown or at the end of a spreading branch and very occasionally built in spruce, larch or Douglas-fir. Clutches are three to four eggs. The diet is mainly made up of seeds of Scots pine (bill shape thought to be better adapted for feeding on cones of this species) and when these are unavailable, it takes seeds, blossom, buds and shoots of larch (Larix), spruce (Picea), fir (Abies), Douglas-fir (Pseudotsuga) and beech (Fagus), and possibly small invertebrates. The species is resident and locally dispersive (Clement 2016).
Suitable semi-natural habitat has declined from approximately 15,000 km2 to fragments totalling 160 km2 over the last 5,000 years. However, the amount of plantation woodland has increased substantially during the 20th century (Clement 2016). Habitat may also be degraded through underplanting with exotic conifers and grazing pressure from high numbers of red deer, which prevents forest regeneration (Tucker and Heath 1994). Climate change may be a threat to the species, through driving changes in habitat, however the provision of habitat through commercial forestry may play a role in mitigating this (Summers and Buckland 2011).
Conservation Actions Underway
EU Birds Directive Annex I. Bern Convention Appendix II. A U.K. Biodiversity Action Plan is being implemented. A survey was conducted in 2008 to assess the current population size (Summers and Buckland 2011). The species is listed as 'amber' on the U.K. national Red List (Eaton et al. 2009).
Conservation Actions Proposed
Carry out further studies to establish whether the species is best adapted to native Scots pine or to plantations of non-native species (and therefore establish the degree of threat it faces). Monitoring of the species needs to be in place in order to determine population trends (Summers and Buckland 2011). Further loss of habitat, from felling and underplanting, needs to be prevented. Red deer numbers should be controlled and excluded with fences to allow the spread of native pinewood (Tucker and Heath 1994).
Text account compilers
Ashpole, J, Calvert, R., Capper, D., Symes, A.
Summers, R., Bainbridge, I.
BirdLife International (2023) Species factsheet: Loxia scotica. Downloaded from http://datazone.birdlife.org/species/factsheet/scottish-crossbill-loxia-scotica on 01/06/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 01/06/2023.