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Drouetius oceanicus is an endemic species with two subspecies: D. o. oceanicus restricted to Terceira island and D. o. tristis present in Corvo, Faial, S. Jorge, Graciosa and S. Miguel islands (Azores, Portugal). It has a relatively large extent of occurrence (EOO = ca 22,000 km²) but a small area of occupancy (AOO = 40 km²). The several subpopulations are highly fragmented and located at lower altitudes in Human modified habitats. Possibly some of them are now extinct. Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change (increasing number of droughts). Based upon the small area of occupancy, the decline in AOO, the decreasing extent and quality of habitat as well as the number of mature individuals as a result of the invasions of non-native plants, urbanisation and pollution, the species is assessed as Endangered (EN).
Drouetius oceanicus is an endemic species with two subspecies: D. o. oceanicus restricted to Terceira island and D. o. tristis present in Corvo, Faial, S. Jorge, Graciosa and S. Miguel islands (Azores, Portugal) (Borges et al. 2010). The species occurs in coastal areas. The extent of occurrence (EOO) is ca 22,000 km² and the maximum estimated area of occupancy (AOO) is 40 km².
The species is extremely rare and there are known subpopulations in low altitude areas in several islands (Corvo, Faial, S. Jorge, Graciosa, Terceira and São Miguel islands). A continuing decline in the number of mature individuals is inferred from the ongoing habitat degradation due to human activities. Recently in 2016 (Borges unpublished data) few specimens were found in the historical site from Terceira in a highly degraded marsh associated with native and exotic plants (Paúl do Belo Jardim). This species is assessed here as severely fragmented as at least 50% of its population can be found in subpopulations that are 1) smaller than would be required to support a viable population, and 2) separated from other habitat patches by a large distance.
This species has two subspecies (D. o. oceanicus restricted to Terceira island and D. o. tristis present in Corvo, Faial, S. Jorge, Graciosa and S. Miguel islands), and occurs in modified native forests (dominated by Erica azorica and Morella faya), exotic forests and marsh areas (in Terceira) (Machado 2009). Adults and larvae are herbivores and feed on plant tissues. The fact that the species is polyphagous facilitates its survival in a highly human modified territory at lower altitudes. However, some of the historical locations are completely destroyed and urbanised or with intensive pastures, which may imply local extinction. The subpopulation of Terceira is located in a small water course near a march area surrounded by an industrial area. This species has an altitudinal range between 0 and 200 m.
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). One of the most important ongoing threat to this species is the continuous change of habitat due to Human activities at lower altitudes. The sites with still native vegetation are also changing due to the spread of invasive plants (e,g, Pittosporum undulatum). Urbanization and pollution are also a problem. Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change (increasing number of droughts).
The species is not protected by regional law. Further spread of invasive plants needs to be stopped in order to avoid any future declines of the species. Degraded habitats should be restored and a strategy needs to be developed to address the future threat by climate change. Formal education and awareness is needed to allow future investments in restored habitats at low elevations. Further research is needed into its ecology and life history in order to find extant specimens at lower elevations and obtain information on population size, distribution and trends. It is also necessary a monitoring plan for the invertebrate community in the habitat in order to contribute to perform a species potential recovery plan. In addition, there is the need of special area-based management plans for most of the subpopulations. Monitoring every ten years using the BALA protocol will inform about habitat quality (see e.g. Gaspar et al. 2011).