VU
Corsican Nuthatch Sitta whiteheadi



Justification

Justification of Red List Category
This species is listed as Vulnerable because its small population has declined in the last decade due to logging and fires, reducing the amount of large, mature Corsican pine Pinus nigra laricio available. Although some forests are regenerating, the slow maturation time of the pine means that potential new habitat does not compensate for the loss of mature pines elsewhere, therefore it is assumed that the population will continue to decline.

Population justification
Thibault et al. (2011) estimated that the population comprised 1,557-2,201 territories/pairs, hence the population is estimated at c.3,100-4,400 mature individuals. This is equivalent to c.4,600-6,600 individuals in total.

Trend justification
Thibault et al. (2011) estimate a decline of 10% during the last 10 years, owing to forest fires and logging, hence the population decline is placed in the band 10-19% over 12 years (three generations). Since 2010 the population has continued to decline with several small patches of forest situated outside the main range abandoned by the species (J. C. Thibault in litt. 2016).

Distribution and population

This species is endemic to Corsica, France (del Hoyo et al. 2008). It has a limited and fragmented breeding range which follows the distribution of Corsican pine Pinus nigra laricio, occurring on inland mountain ridges from Tartagine south to Ospedale and Mt Cagna, with main concentrations in the centre and north of the island (Harrap et al. 2016). Thibault et al. (2011) estimated that Corsican Nuthatch territories occupy c.185 km2 of pine stands on Corsica. The first survey throughout its range was conducted between 1997 and 2008, estimated the population to be 1,557-2,201 territories, and estimated that the population had declined by c.10% in the last ten years due to fire and logging (Thibault et al. 2011). A recent study of the species's genetic structure found two groups separated by only several thousand years: one group localized in the northern limit of the range and clearly delimited by the topography, and declining recently because of fires (Tartagine, Melaja), the other group occupying the rest of the island (Thibault et al. 2016).

Ecology

Behaviour Forages singly or in pairs, though may join mixed-species flocks outside the breeding season (Harrap et al. 2016). Seeds are cached from late autumn to early spring during periods of sunny weather (when the cones are open) and retrieved during wet or cold weather (Thibault et al. 2006). Its breeding season stretches from April to May, laying a clutch of 5-6 eggs, with mated partners remaining on their territory all year (Harrap et al. 2016).It is generally sedentary except for some dispersal of immature and unmated birds to lower altitudes in winter (Thibault and Bonaccorsi 1999). Habitat Optimal habitat for this species is mature stands of Corsican pine with abundant dead and rotting trunks for nest sites, at elevations of 1,000-1,500 m (Harrap et al. 2016), usually in mature stands that are at least 150 years old (Villard et al. 2014). Densities vary between 0.55 and 1.58 pairs/10 ha (Thibault et al. 2002), and correlate with tree height, vegetation density and dead tree distribution (Thibault and Bonaccorsi 1999). Suboptimal habitats include forests where Corsican pine is associated with cluster pine P. pinaster, balsam fir Abies alba or beech Fagus sylvatica, and younger, exploited stands of Corsican pine at elevations of 600-1,750 m (Thibault and Bonaccorsi 1999, del Hoyo et al. 2008). A recent study found highest nuthatch densities in old stands of pure Corsican pine with very low numbers or no nuthatches in cut areas, areas with young trees or areas without Corsican pine (Villard et al. 2014). Dispersing birds may be found in holm oak Quercus ilex and sweet chestnut Castanea sativa forests, gardens and orchards (Thibault and Bonaccorsi 1999, del Hoyo et al. 2008). Diet Feeds largely on insects and spiders during May-October, switching to seeds, especially those of the Corsican pine, during the rest of the year (Thibault et al. 2006).

Threats

Forest fires and logging of mature Corsican pine stands appear to be the primary threats to this species. Large trees suitable for the species are also favoured by the logging industry and since the 1970s local foresters have attempted to rejuvenate the pine forest by shortening the logging rotation, reducing the size of trees available for the species (Bourcet 1996). It has been estimated that 78-122 territories have been destroyed by logging since 1998, and that a further 50-63 territories were lost during the large forest fires of 2000 and 2003, which severely affected another 47-80 territories (Moneglia et al. 2009, Thibault et al. 2004, 2011). It has been predicted that whenever an area >2 ha is logged in a forest stand suitable for the species, a potential territory is likely to disappear for more than a century due to the slow growth of Corsican  pine (Thibault et al. 2011). In harvested forests the species abandons areas when deciduous trees represent more than 50% of the stand (Villard et al. 2014). This species is potentially susceptible to climate change through sea-level rise and shifts in suitable climatic conditions (affecting Corsican pine distribution), however this is not expected to be a serious direct threat (Barbet-Massin and Jiguet 2011; BirdLife International unpublished data). Climate change may also cause an increase in fire frequency and intensity, promoting the Maritime Pine that is more able to persist after fire (Pimont et al. 2011) and so could be a serious future threat to the species (Barbet-Massin and Jiguet 2011, J. Baudat-Franceschi in litt. 2010). Climate change may increase interspecific competition between Corsican pine and Maritime pine Pinus pinaster as well as Mediteranean shrub species which in turn could have a negative effect on the species's range (Thibault et al. 2010, J. Baudat-Franceschi in litt. 2012).

Conservation actions

Conservation Actions Underway
EU Birds Directive Annex I. The species is nationally considered to be Vulnerable (IUCN 2011). There are no natural reserves dedicated to the species on Corsica (J. C. Thibault in litt. 2016) although almost the entire global population occurs within the Natural Regional Park of Corse (Harrap et al. 2016). Work is being conducted by forest managers to promote irregular stand cutting, to reduce size of felling coupes, and to keep a fairly good number of old stand islets (Office national des Forêts 2006, Ministère de l’Environnement, de l’Energie et de la Mer 2016). All snags of Corsican pine are now preserved (J. C. Thibault in litt. 2016).

Conservation Actions Proposed
Research the minimum size of a Corsican pine stand required to support a viable population. Prevent the logging of mature Corsican pine. Ensure that forest management practices are not detrimental to Corsican Nuthatch: in harvested forests reduce the size of felling coupes to <2 ha each; retain at least eight large trees (>70-80 cm diamer at breast height) per hectare in harvested plots; retain snags or dead trees at a similar density within groups of live trees; ensure that the percentage of tree species other than Corsican pine is <50% of the basal area of all trees (Villard et al. 2016). Develop a plan to prevent forest fires. Prevent the clearance of dead and rotting trunks in managed forests.

Acknowledgements

Text account compilers
Butchart, S., Calvert, R., Derhé, M., Ekstrom, J., Ashpole, J

Contributors
Baudat-Franceschi, J., Thibault, J.


Recommended citation
BirdLife International (2017) Species factsheet: Sitta whiteheadi. Downloaded from http://www.birdlife.org on 22/11/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/11/2017.