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Calacalles azoricus is an endemic species from Faial (Azores, Portugal). It has a very small extent of occurrence (EOO = 4 km²) and area of occupancy (AOO = 4 km²). There is a continuing decline in the EOO, AOO, extent and quality of habitat as well as the number of mature individuals as a result of the invasions of non-native plants. The species occurs only at one location and is associated with an endemic rare plant (Tolpis azorica). Therefore, we suggest as future measures of conservation: (1) regular monitoring of the species; and (2) control of invasive species namely Hedychium gardnerianum and Rubus ulmifolius. Based upon the small geographic range of the species with only one location and continuing decline of its habitat area and quality, it is assessed as Critically Endangered.
Calacalles azoricus is a single island endemic species from Faial (Azores, Portugal) (Borges et al. 2010), known from Natural Forest Reserve of Caldeira do Faial. The extent of occurrence (EOO) is 4 km² and the maximum estimated area of occupancy (AOO) is 4 km².
The species is very rare and only known from a single subpopulation in Faial island. A continuing decline in the number of mature individuals is inferred due to restricted distribution and host-plant rarity (Tolpis azorica).
The species occurs in native forests of high altitude in the Faial island (Azores), with an altitudinal range between 800 and 1000 m. Adults and larvae are herbivores and feed of plant tissues (Tolpis azorica).
In the past, the species has probably strongly declined due to changes in habitat size and quality (Triantis et al. 2010, Terzopoulou et al. 2015). Currently invasive plants (Hedychium gardnerianum and Rubus ulmifolius) are changing some of the areas and decreasing the quality of the habitat, as they are changing the habitat structure, namely decreasing the cover of bryophytes and ferns in the soil and promoting the spread of other plants. Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change (increasing number of droughts and habitat shifting & alteration).
The species is protected by regional law (RAA 2008). Its habitat is in a regionally protected area (Natural Park of Faial). Degraded habitats should be restored in Caldeira do Faial and of critical importance is the removal of invasive non-native species where this is possible. A strategy needs to be developed to address the future threat by climate change. A habitat management plan is needed and anticipated to be developed during the coming years. Formal education and awareness is needed to allow future investments in restored habitats invaded by invasive plants. Further research is needed into its ecology and life history in order to find extant specimens and obtain information on population size, distribution and trends. It is also necessary an area-based management plan and a monitoring plan for the invertebrate community in the habitat in order to contribute to perform a species potential recovery plan. Monitoring every ten years using the BALA protocol will inform about habitat quality (see e.g. Gaspar et al. 2011).