Assessment Rationale:

Drouetius azoricus is an endemic species with four subspecies, D. a. azoricus present in Faial, S. Jorge and Graciosa islands; D. a. nitens present in Occidental group (Corvo and Flores islands); D. a. parallelirostris restricted to Terceira island and D. a. separandus restricted to S. Miguel island (Azores, Portugal). It has a relatively large extent of occurrence (EOO = ca 23,800 km²) but a small area of occupancy (AOO = 76 km²).  The several subpopulations are highly fragmented and located at lower altitudes in Human modified and disturbed habitats. 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, the species is assessed as Endangered (EN).

Geographic Range:

Drouetius azoricus is an endemic species with four subspecies, D. a. azoricus present in Faial, S. Jorge and Graciosa islands; D. a. nitens present in Occidental group (Corvo and Flores islands); D. a. parallelirostris restricted to Terceira island and D. a. separandus restricted to S. Miguel island (Azores, Portugal) (Borges et al. 2010).  D. a. parallelirostrisis known from a small area in Terceira Natural Park. The extent of occurrence (EOO) is ca 23,800 km² and the maximum estimated area of occupancy (AOO) is 76 km².

Population:

The species is rare (very few number of specimens known) and known from subpopulations in low altitude areas in several islands (Corvo, Flores, Faial, S. Jorge. Graciosa, Terceira and S. Miguel islands). A continuing decline in the number of mature individuals is inferred from the ongoing habitat degradation due to human activities at lower altitudes. 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.

Habitat and Ecology

This species has four subspecies (D. a. azoricus present in Faial, S. Jorge and Graciosa islands; D. a. nitens present in Occidental group (Corvo and Flores islands); D. a. parallelirostris restricted to Terceira island and D. a. separandus restricted to S. Miguel island), and occurs in modified native forests (dominated by Erica azorica and Morella faya) exotic forests and semi-natural pastures (Machado 2009). This species has an altitudinal range between 0 and 500 m. Adults and larvae are herbivores and feed on plant tissues. It is frequent to find specimens in caves, since the adults stay underground during the day. The fact that the species is polyphagous facilitates its survival in a highly human modified territory at lower altitudes.

Major Threat(s):

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 keeping native vegetation are also changing due to the spread of invasive plants (e.g. Pittosporum undulatum). Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change (increasing number of droughts).

Conservation Actions

The species is not protected by regional law. Its habitat is in a regionally protected area (Natural Park of Terceira). In the other six islands none of subpopulations are located within the range of protected areas. 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 in all the historical localities and obtain information on population size, distribution and trends. It is also necessary for a monitoring plan for the invertebrate community to be developed in the habitat in order to contribute to perform a species potential recovery plan in many of the historical localities. In addition, there is the need of special area-based management plans for most of the subpopulations.