This species has a very patchy distribution in Hispaniola, suggesting that it has declined from a previously more uniform distribution. It has an altitudinal range from sea level to 1,697 m asl (Henderson and Powell 2009). Surveys conducted between 2008-2010 have recorded this frog at 15 geographic localities of the Dominican Republic including Nalga de Maco, San José de las Matas, San José de Ocoa, Salto de la Damajagua, Diego de Ocampo, La Vega, La Canela, Monte Plata, Sanchez Ramírez, Ebano Verde, Guaconejo, La Humeadora, Bonao, Miches and Los Haitises. These surveys have expanded its area of occupancy (AOO) since its last assessment in 2004 (G. Ross pers. comm. March 2011). However, even considering this expansion, the occupied area (herein taken as a proxy for AOO, although the actual AOO would be more restricted as some sites consist of small ponds beyond the margins of which frogs cannot survive) in the Dominican Republic is estimated to be 1,165 km
Habitat and Ecology
It is found in mesic broadleaf forests, and has more recently been recorded in cacao and coffee plantations, pastures, and other types of crop agriculture (e.g., avocados and yams)(Pueblo Viejo Dominicana Corporation pers. comm. January 2012; Pueblo Viejo Dominicana Corporation pers. comm. July 2012). Recent surveys have revealed that, of a total of 96 transects, the species was found primarily in different forest types (N=85), but it was also recorded in agricultural areas (N=7) and wetlands (N=4)(Pueblo Viejo Dominicana Corporation pers.comm. July 2012). Most of the surveyed transects (N=74) had various land use practices in the surrounding area, with 22 transects surrounded by unaltered forests (Pueblo Viejo Dominicana Corporation pers.comm. July 2012). Within these different habitat types it can often be found along creeks and streams, although it has also been recorded in marshes (Pueblo Viejo Dominicana Corporation pers. comm. July 2012). In Haiti it has been recorded in pine forests, but not so in the Dominican Republic (M. Rodriguez pers. comm. March 2011). Males call from trees overhanging running water, in which eggs are deposited. Many individuals were detected high in the canopy (up to 15 m). It is possible that species may find refuge high in the canopy during the day (G. Ross pers. comm. March 2011). Although this frog is found in habitat types that are contained within a variety of different land uses, the survey results above suggest that it requires forests as the main habitat pockets to subsist within these different landscapes.
It is more common than Osteopilus pulchrilineatus in the Cordillera Central. This species is more commonly seen as lone individuals, with occasional breeding couples (G. Ross pers. comm. March 2011). It was found just outside Santo Domingo in 2001-2002, and during 2008-2010 surveys this species was frequently observed, with 182 mature individuals on record (G. Ross pers. comm. March 2011). Dead individuals found prior to the 2004 assessment are suggestive of some past localized declines. The population is considered to be severely fragmented as per the IUCN Red List Guidelines, i.e. it occurs in fragmented habitat patches, it has a poor dispersal ability and limited gene flux, and 50% or more of individuals are found in isolated and fragmented habitat patches.
In Haiti, severe degradation of streams has already significantly altered one of its breeding habitats, and streams in Hispaniola in general are being highly impacted by deforestation due to agricultural activities, logging and charcoaling (B. Hedges pers. comm. February 2012). Suitable habitat where the species is currently found is being impacted by mining activities (Barrick Gold Corporation 2012). Infrastructure development is also a threat in some areas in the Dominican Republic. M. Hernández (pers. comm.) had found dead animals and animals with deformities (one animal with an eye on its back), and declines in suitable habitat are suggestive of chytridiomycosis. Indeed, chytrid was confirmed in this species in La Vega, Arroyazo, and in Sanchez Ramírez (2009), in the Dominican Republic (G. Ross pers. comm. March 2011). Small numbers are being exported to the US for the pet trade, suggesting that they are being harvested in the wild.
Its range includes several protected areas, although most of these are in need of improved biodiversity conservation management. Small isolated populations outside of protected areas are thought to be at a very high risk of local extirpation within the next ten years if there is no intervention (R. Powell pers. comm. February 2012), so additional habitat protection is urgently required. Further survey work is necessary to determine the current population status of this species in the wild in Haiti, and to determine the possible effects of chytrid as a threat. The Dominican governmental agency Ministerio de Educación Superior, Ciencia y Tecnología (MECyT) is currently financing a three-year Dominican conservation project on threatened frogs due to climate change (RANA-RD), and which is expected to contribute towards a national Dominican amphibian conservation action plan with policy recommendations (C. Marte, M. Rodríguez and L. Diaz pers. comm. March 2011). Barrick Gold Corporation is funding a biodiversity project to establish assurance colonies of this and other Hylids impacted by its mining operation, and is also involved in building capacity and collecting additional biological information (Barrick Gold Corporation 2012).
The Amphibian Ark Conservation Needs Assessment process (Amphibian Ark 2011) conducted in the joint IUCN-Amphibian Ark workshop where this species was reassessed identified that further conservation actions for this taxon should include in situ conservation and conservation education.
The subpopulation in the "South Island" of Haiti may likely comprise a new taxon, currently under study (B. Hedges pers. comm. February 2012). Therefore, the true distribution of Osteopilus vastus may exclude Haiti and the southern portion of the Dominican Republic. However, for the purposes of this assessment, this subpopulation is included in the current assessment until such time as it is formally described.
IUCN SSC Amphibian Specialist Group, 2013. Osteopilus vastus. In: IUCN 2014