Justification of Red List Category
This species is listed as Least Concern as, thanks to successful conservation efforts, it no longer approaches the thresholds for Vulnerable under any of the IUCN criteria. Although it has a very small range and small population, the species is now increasing in numbers.
The population is estimated at 10,000-14,000 mature individuals (BirdLife International 2015).
The species's population recovered rapidly following a ban on hunting in 1986. It increased from an estimated low of 2,700 individuals to more recently 8,500 to 10,000 individuals, although there is some fluctuation (Oliveira et al. 2007, Barov and Derhé 2011). The most recent assessment of the species's population estimates the trend as stable (BirdLife International 2015).
This species is endemic to Madeira and formerly the neighbouring island of Porto Santo, Portugal. It is found predominantly on the island's mountainous northern slopes, but can also be seen on a few isolated laurel forest pockets in the south. It was very abundant in the early years of human colonisation, but subsequently declined dramatically to c.2,700 birds in 1986 (Oliveira et al. 1999). However, the population recovered rapidly soon after the ban on hunting in 1986. Since then, estimates put the population at between 8,500 and 10,000 individuals (Oliveira et al. 2007, BirdLife International 2010, P. Sepúlveda in litt. 2011) in approximately 160 km2 of suitable habitat (P. Oliveira in litt. 1999, Oliveira et al. 1999). The most recent population estimate is 10,000-14,000 mature individuals (BirdLife International 2015). The species is now widespread throughout all areas of laurel forest, and has reoccupied many parts of its former range that it had previously deserted (Madeira National Park Service in litt. 2010). Tracewski et al. (2016) estimated the maximum Area of Occupancy (calculated as the remaining tree area within the species’s range) to be 13.65 km2, however the laurel forest is said to be increasing in area (C. Gouveia in litt. 2017) and the species is being found outside of the laurel forest (C. Gouveia in litt. 2017), so this is considered to be an underestimate.
The species is confined to laurel forest, largely below 850 m (Oliveira et al. 1999). There is strong evidence that it is highly mobile between different areas at different times of year (Oliveira et al. 2006). It nests in trees in laurel forest, occasionally on the ground or in cavities in cliffs. Normally only one egg is laid. The species is largely frugivorous, although leaves and flowers are also well represented in its diet: at least 33 different species are taken (Oliveira et al. 2002). It feeds mainly on the berries of Laurus azorica which is the most common tree in the laurel forest (Tucker and Heath 1994). It also eats the fruit of Ocotea foetens, Persea indica, Appolonias barbujana, Myrica faya, Clethra arborea and Piconia exelsa (Zino and Zino 1986, Jones 1988, Tucker and Heath 1994). Birds may also feed on agricultural land (Marrero et al. 2004, Oliveira et al. 2006) where it forages on cabbages, watercress and fruit trees (Tucker and Heath 1994).
Extinction on Porto Santo and historical declines on Madeira were directly related to forest destruction for wood, agriculture, grazing and human settlements. Laurel forests have been reduced to only 13.5% of surface area of Madeira (Baptista et al. 1997). Regeneration and expansion of the forest is now ensured with the removal of livestock from the forest. This species's unpopularity, as a result of its use of agricultural areas, has a negative influence on conservation and management actions. Hunting and poisoning, as a result of the damage done to crops, continue illegally in a few well-defined areas, especially on agricultural land, and in response to farmers' protests, the regional government authorised limited culling of the species on one occasion in 2004 (Nagy and Crockford 2004). Nest predation by black rat Rattus rattus is likely to be a factor limiting reproduction.
Conservation Actions Underway
EU Birds Directive Annex I. It is legally protected and hunting was banned in 1986. Madeira Natural Park has a management plan, and an action plan for the species was published in 1996. All key sites are now protected and habitat restoration has expanded the area of laurel forest (Barov and Derhé 2011). Farmers suffering crop damage are provided with free bird-scaring devices, and several government control programmes have been implemented, reducing levels of illegal hunting and poisoning (Barov and Derhé 2011). Work has been undertaken to remove cattle from some areas and control invasive species in laurel forest, as well as measures to reduce the incidence of fire (Barov and Derhé 2011).
38-40 cm. Dark grey and purple pigeon. Adult has blue-grey head and foreneck, grey glossed green sides of neck with bold patch of silver-tipped feathers. Slate grey scapulars and wing-coverts and black-brown flight feathers. Blue-grey back and rump. Reddish-purple breast and rest of underparts blue-grey. Slate black tail with broad, pale grey subterminal band. Red bill, pale yellow eye and red orbital ring. Red legs. Juvenile is duller and browner lacking glossed plumage. Voice Rhythmic, sonorous oo coo coo coo-coo.
Text account compilers
Symes, A., Wheatley, H., Taylor, J., Ashpole, J, Capper, D., Peet, N., Westrip, J., Ekstrom, J., Bird, J.
Gouveia, C., Oliveira, P., Sepúlveda, P., Menezes, D.
BirdLife International (2019) Species factsheet: Columba trocaz. Downloaded from http://www.birdlife.org on 18/04/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/04/2019.