Justification of Red List Category
This species is listed as Near Threatened because it has a small range, in which it faces the limited threats of habitat clearance and degradation owing primarily to agricultural encroachment and logging, but is not severely fragmented, and it is thought to have a moderately small and declining population. The terrain in the areas it occupies is likely to prevent serious damage to its habitat, but this requires close monitoring.
BirdLife International estimates the species's EOO at 13,400 km2, based on information provided by Lammertink et al. (1996). It is estimated that 65-90% of the species range is occupied by home ranges (M. Lammertink in litt. 2010) , resulting in an estimate of 8,700-12,000 km2 of occupied habitat. An estimate of 3 km2 per territory is derived from Croisin (1967) by M. Lammertink (in litt. 2010), suggesting that there are 2,900-4,000 groups in total. Each group has two adults and 9.3 individuals (n=7), implying that there are 5,800-8,000 breeding adults within a population of 27,000-37,200 individuals. Based on the supposition that there are more than two mature individuals per group, the population is placed in the band for 10,000-19,999 mature individuals.
Although some populations may be stable, the overall population is suspected to be in slow decline (M. Lammertink in litt. 2010, C. Villar Rodríguez et al. in litt. 2012) owing to the species's susceptibility to forest destruction (Madge and Burn 1993). The rate of decline may accelerate over the next three generations (C. Villar Rodríguez et al. in litt. 2012).
Cyanocorax dickeyi is restricted to montane areas of north-west Mexico, where it is fairly common on the Pacific slope of the Sierra Madre Occidental, with the core of its range from Sinaloa and Durango to north Nayarit (Crossin 1967, Howell and Webb 1995a, Lammertink et al. 1996). Surveys in 1994-1995 extended the known north-south distribution of the species from 210 km to 295 km, by finding it north of the río de Presidio, and probably to the San Lorenzo/Los Remedios river complex (Lammertink et al. 1996). More recent records further extend its known range, with a new site found in 2011 in Baborigame, Chihuahua, as well as new localities found in Durango and Nayarit since 2009 at least (C. Villar-Rodríguez et al. in litt. 2012).
The species largely inhabits humid canyons within semi-deciduous and pine-oak forests at elevations of 1,350-2,150 m (Madge and Burn 1993, Howell and Webb 1995a, Lammertink et al. 1996). Flocks occasionally wander into the mesa forests at higher altitudes, but do not seem to avoid selectively logged areas (Lammertink et al. 1996). It spends most of its time in the canopy, rarely descending to the ground (Madge and Burn 1993). Its diet comprises invertebrates, fruits, berries and acorns. It is a cooperative breeder, with breeding groups consisting of one breeding pair of adults and several non-breeding immature birds. Three to five eggs are laid in April and early May. Its nest is a bulky structure of sticks and twigs, lined with finer twigs and plant material, and situated 5-15 m above the ground in the dense canopy of a tree. The incubation period is 18-19 days, followed by a fledging period of c.24 days (Madge and Burn 1993).
Canyon forest is relatively inaccessible and not as susceptible to logging and conversion to agriculture as surrounding areas (Lammertink et al. 1996, J. M. Lammertink in litt. 1998, 2010). Some of the species's habitat is cleared for the cultivation of narcotics, although it may be able to tolerate such limited and localised fragmentation (J. M. Lammertink in litt. 2010, C. Villar Rodríguez et al. in litt. 2012), but it is though likely that the species suffers some persecution from those people who attend such crops (J. M. Lammertink in litt. 2010). It is also hunted by children (J. M. Lammertink in litt. 1998), and it may suffer some reduced reproductive success owing to direct persecution of nesting birds, usually directed towards crows (Corvidae) in some locations (C. Villar Rodríguez et al. in litt. 2012). The species's food resources have been reduced in some areas by heavy droughts in recent years, forcing birds to forage in new areas, and the population could potentially undergo rapid declines owing to the prolonged droughts that could be associated with projected climate change (C. Villar Rodríguez et al. in litt. 2012). Breeding groups may be affected by the uncontrolled felling of pine-oak forest, which occurs predominantly in the dry season (and can extend from October to May), and thus coincides with the species's breeding season (C. Villar Rodríguez et al. in litt. 2012). Suitable habitat is also destroyed and degraded by forest fires, which may affect large areas of forest, owing to altered fire regimes. Road construction has fragmented habitat and is likely to impact the species. Some of the springs used by family groups have been lost to human activities (C. Villar Rodríguez et al. in litt. 2012).
Conservation Actions Underway
No targeted conservation actions are known for this species, although it is being studied in some areas (C. Villar Rodríguez et al. in litt. 2012). It is on the watch list as part of the State of North America's Birds (North American Bird Conservation Initiative 2016).Conservation Actions Proposed
Conduct surveys to better assess the species's population size. Carry out regular surveys to monitor population trends. Monitor habitat loss and degradation within the species's range. Protect suitable habitat. Introduce regulations to require that logging take place during the species's non-breeding season (C. Villar Rodríguez et al. in litt. 2012). Carry out research to assess the threat from droughts associated with climate change. Conduct awareness-raising activities to reduce persecution.
Text account compilers
Isherwood, I., O'Brien, A., Taylor, J., Westrip, J.
Torres, F., Torres, F., Villar-Rodriguez, C., Gonzalez-Bernal, M., Vidal, R., Cruz-Nieto, M.Á., Vega-Picos, X., Lammertink, M., Cruz, J., Escarcega-Bencomo, M.
BirdLife International (2019) Species factsheet: Cyanocorax dickeyi. Downloaded from http://www.birdlife.org on 17/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/11/2019.