Resurveys Reveal Potential Population Increases of the Himalayan Griffon in Central West Nepal
The Himalayan Griffon (Gyps himalayensis) is listed as near threatened and its populations are poorly monitored. During late May and early June of 2013, 2014, and 2016, we resurveyed transects that were originally sampled 2002–2006. These transects were within the Annapurna region of Nepal. From 2010 through 2020, we also monitored a breeding colony of Himalayan Griffons within the Arghakhanchi District of Nepal. The number of non-adults, adults, and total Himalayan Griffons counted along the transects approximately doubled from the previous counts. At the colony, the number of breeding pairs and young fledged increased during the study (yearly growth rate [r] = 0.049 and 0.089, respectively). The number of offspring fledged per breeding pair also increased (r = 0.040). Our results are encouraging, but we only surveyed a small portion of the global population and over a relatively short time period. We recommend expanded and coordinated population monitoring for this species across its range. Nuevos Censos Revelan Posibles Aumentos Poblacionales de Gyps Himalayensis en el Centro Oeste de Nepal Gyps himalayensis está catalogada como una especie Casi Amenazada, estando sus poblaciones pobremente evaluadas. Entre finales de mayo y principios de junio de 2013, 2014 y 2016, realizamos nuevos censos en los transectos que fueron muestreados originalmente en 2002–2006 en este pais. Estos transectos se localizaron dentro de la región de Annapurna, Nepal. Del 2010 al 2020 también evaluamos una colonia reproductora de G. himalayensis en el distrito de Arghakhanchi, Nepal. El número de individuos no adultos, adultos y total de G. himalayensis contados a lo largo de los transectos aproximadamente se duplicó con respecto a los conteos anteriores. En la colonia, el número de parejas reproductoras y de volantones aumentó durante el estudio (tasa de crecimiento anual [r] ¼ 0.049 y 0.089, respectivamente). El número de volantones por pareja reproductora también aumentó (r ¼ 0.040). Nuestros resultados son alentadores, pero solo muestreamos a una pequeña parte de la población mundial de esta especie y durante un período de tiempo relativamente corto. Recomendamos un seguimiento poblacional ampliado y coordinado para esta especie en toda su área de distribución. [Traducción del equipo editorial]ABSTRACT
RESUMEN
Map of Nepal. Black points depict the locations of sightings of Himalayan Griffons along the transect during 2013, 2014, and 2016; and the blue triangle depicts the location of the breeding colony surveyed from 2010 through 2020.
Average (points) and standard errors (lines) of Himalayan Griffons observed per day along a walking transect from Muktinath to Pokhara, Nepal, from 2002 through 2006 and during 2013, 2014, and 2016.
(A) Observed (points) and estimated (solid and dotted lines; shaded areas = 95% credible interval [CRI]) counts of occupied nests and fledglings in a breeding colony of Himalayan Griffons from 2010 through 2020. (B) Observed (points) and estimated (line; shaded area = 95% CRI) number of fledglings per nest (productivity) in a breeding colony of Himalayan Griffons from 2010 through 2020.
Contributor Notes
1 Email address: cmcclure@peregrinefund.org