Endangered. Conservation of the Puerto Rican Nightjar greatly depends on the continued protection of the coastal dry and lower cordillera forest reserves of Guánica and Susúa. These reserves, managed by the Puerto Rico Department of Natural and Environmental Resources' (DNER) Forestry Division encompass some of the best nightjar habitat remaining as well as unique floristic associations. Habitat management options available will depend primarily on whether nightjars are found in private or public lands, due to access limitations and control over land use practices encountered on private lands. Presently, the most urgent conservation need for nightjars within privately owned land is habitat protection.
Establishing a system of forest reserves, equivalent to Guánica and Susúa, in the Guayanilla-Peñuelas region would be a major conservation step for the Puerto Rican Nightjar. With the exception of the small private reserve (≈230 ha) owned by the Puerto Rico Conservation Trust in the Guayanilla Hills, no protected areas exist in this important portion of the species' range. The Guayanilla-Peñuelas region includes a considerable amount of quality habitat and is home to the second largest nightjar population after Guánica-Ensenada. It also includes several other threatened and endangered species of both animals and plants typical of the dry forests of the island's southwest (Lugo et al. 2001). The amount of terrestrial protected areas in Puerto Rico is currently below the regional average (i.e., 8.6% of land area) for the Caribbean and Central America (World Resources Institute 2003, Gould et al. 2007).
Measures can be taken to mitigate the impacts of changes on areas that presently possess nightjars and will likely remain under private ownership. Information on the nightjar and the benefits of conserving the region's coastal dry forests should be made available to pertinent landowners. Additionally, reforestation using a mixture of mahogany (at appropriate stocking densities) and native tree species (e.g., Bucida buceras, Bursera simaruba, Pisonia albida, Exostema caribaeum) should be strongly encouraged. While mahogany is not native to Puerto Rico it has become naturalized over the last 100 years and is widespread on the island. Commercial varieties of mahogany are fast-growing and generate abundant leaf litter. These mixed forest stands, such as the ones found in the uplands of Guánica Biosphere Reserve, would benefit Puerto Rican Nightjars. Landowners within nightjar occupied range should be encouraged to pursue silvicultural practices that promote nightjar nesting habitat and informed of conservation programs (e.g., Partners for Fish and Wildlife) available for private lands (CEDES 2007).
Effects of human activity on populations
Land use pressures exist in the areas surrounding the Guánica Biosphere Reserve and Susúa Forest, and even within the reserves themselves. Numerous housing and tourism projects have been proposed for areas adjacent to both reserves. While no major housing or resort development has occurred in lands surrounding Guánica Forest, a major landfill was established north of the reserve boundaries. The opening and paving of the Guánica Forest's system of roads has been proposed on several occasions by the municipal governments of adjacent towns (Canals 1990). This is of concern as any disturbance to the trail system of Guánica Forest could have negative consequences for the upland forest associations where the majority of the nightjar nesting activity is found. Similarly, private lands in the periphery of Susúa Forest continue to be fragmented and nightjar habitat disturbed through road construction and residential development. The absence of forest reserves in the Guayanilla-Peñuelas region has led to increased fragmentation and deforestation for residential development.
All these activities involve permanent alteration of occupied nightjar habitat. The sedentary nature of the nightjar and its link to mature, closed-canopy forest provides little room for what proponents may visualize as minor habitat alterations. The continuing deforestation and fragmentation of privately owned tracts of nightjar habitat is the single most important limiting factor affecting the species. This is of concern considering that most predicted nightjar habitat occurs on private lands. For example, a number of forest fragments in southeastern Puerto Rico at the eastern limit of the species' range have not been considered in conservation planning (Vilella and González 2009). As such, these fragments are not included as DNER conservation priority areas nor have they been recognized as representing Important Bird Areas. While these are relatively small fragments, the importance of small reserves as habitat refugia for species such as the nightjar, as well as their restoration potential, should not be overlooked (Shafer 1995). Forest fragments throughout nightjar occupied range should be assessed for their conservation and restoration potential.
Land uses such as industrial development that promote forest clearing should not be allowed in the periphery of Guánica Forest. A windfarm project has been approved for Punta Verraco, an area on the southeastern boundary of Guánica Forest located within the buffer zone of this UNESCO Biosphere Reserve. Biosphere Reserves are mandated to protect their peripheral buffer zones and promote the establishment of corridors along these buffers (Dyer and Holland 1991). Concerns have been raised by the scientific community and environmental organizations of Puerto Rico, not as much for the nature of the project as renewable energy ventures such as windfarms are desirable, as for its proposed location. The project requires establishing a system of major service roads and clearings for wind turbines on what was previously a large continuous area of semi-deciduous and evergreen forest. This project has the potential to negatively impact the resident nightjar population and its habitat. A network of service roads will promote corridors for exotic predators (cats and mongoose) and increase the potential for forest fires. Also, the edge effect of roadside habitats and clearings often extends into the surrounding forest, with a consequent decrease in habitat quality beyond the actual hard edge of the road (Amor and Stevens 1976, Vilella and Zwank 1993b).