Potential distribution, absolute density, and population size of Gray-backed Hawks (Pseudastur occidentalis) in a protected area in northwest Peru

Abstract

Estimates of density and population size are fundamental in assessing population trends and ultimately in informing conservation management. Although the abundance of raptors is often expressed as indices of relative abundance, these can be poor correlates of absolute density. In 2008–2009, I calculated the absolute density and population size of Gray‐backed Hawks (Pseudastur occidentalis), an endangered species and Tumbesian endemic, using line transect counts in four different habitat types in a protected area in northwestern Peru. The absolute density of Gray‐backed Hawks in northwest Peru was estimated to be 0.65 individuals km−2, and the most suitable habitat for the species was located in the provinces of Manabí, Guayas, and Santa Elena in Ecuador, and Tumbes and Piura departments in Peru. The population of Gray‐backed Hawks in my study areas in Tumbes was estimated to be 136, with 94% occurring in dry deciduous and deciduous forest. Because ∼60% of all detections in my study were made outside strictly protected areas, including the recently created Angostura‐Faical Regional Conservation Area, conservation of the remaining, non‐protected forests patches in Peru and Ecuador should be a high priority. The current global population of Gray‐backed Hawks has been estimated to be between 250 and 999 birds and declining due to ongoing habitat destruction and fragmentation. Small populations in small habitat fragments, like those in my study area, have high conservation potential, provided that populations are not isolated, and hence should be the focus of constant monitoring.

Citizen science data reveals the cryptic migration of the Common Potoo Nyctibius griseus in Brazil

“…Although the use of citizen science data in North America and Europe has outpaced other regions (Callaghan et al . 2019), citizen science data have been used in South America to document single species distributions (Piana 2016, Hernández et al . 2019, Domínguez et al .…”

“…In recent years, citizen science data have emerged as a powerful tool that can be used to track avian diversity (Callaghan et al 2019), species distributions (Sullivan et al 2014, Fink et al 2020, mortality (Loss et al 2014) and population trends (Horns et al 2018, Neate-Clegg et al 2020 to inform conservation planning (Callaghan & Gawlik 2015, Sullivan et al 2017. Although the use of citizen science data in North America and Europe has outpaced other regions (Callaghan et al 2019), citizen science data have been used in South America to document single species distributions (Piana 2016, Hern andez et al 2019, Dom ınguez et al 2020, climate-driven range expansion (Hayes et al 2018), distribution of functional groups in urban areas (Guti errez-Tapia et al 2018), wintering range of a North American migrant (Klipp et al 2018), migratory pathways (Pollack-Vel asquez et al 2020) and drivers of bird-window collisions (Rebolo-Ifr an et al 2019) and to assess the potential impact of resource extraction on Neotropical migrants (Rodewald et al 2019). The comparative dearth of citizen science research can be attributed to the availability of less complete data (Callaghan et al 2019, La Sorte & Someveille 2020, necessitating the use of datasets in addition to eBird (Lees 2016, Schubert et al 2019.…”