Surveying Two Endangered Primate Species (Alouatta palliata aequatorialis and Cebus aequatorialis) in the Pacoche Marine and Coastal Wildlife Refuge, West Ecuador

Abstract

Accurate information on the distribution, demography, and conservation status of endangered populations in threatened habitats are essential to provide the basis for conservation actions and management plans. Neglect of western Ecuador by biologists has resulted in a paucity of information of primate populations in the region. Capuchins (Cebus spp.) and howlers (Alouatta sp.) occur in the Tumbes-Chocó-Magdalena hotspot along the Pacific coast. We conducted the first primate survey in Pacoche Marine and Coastal Wildlife Refuge, one of the few protected areas in western Ecuador. Although the Pacoche refuge is protected, illegal activities inside the area include slash-and-burn agriculture and natural resource extraction. We surveyed 18 1-km transects within the protected area between April and July 2012 to evaluate the effects of anthropogenic disturbance and habitat characteristics on population densities of the Critically Endangered Ecuadorian white-fronted capuchin (Cebus aequatorialis) and the Vulnerable mantled howler (Alouatta palliata aequatorialis). We confirmed the presence of C. aequatorialis through direct observation on three occasions outside transects. The low detection rate of C. aequatorialis underscores the need for immediate conservation action for this species. Using a hierarchical distance sampling model, we predicted group size as a proxy of probability of detection and found that canopy cover explained group density of A. p. aequatorialis, following a half-normal Int J Primatol distribution. We estimated the mean density of A. p. aequatorialis as 12.4 ind./km 2 and the total population to be 621.5 individuals. The correlation between the density of A. p. aequatorialis and canopy cover underlines the need to preserve the remaining forest and its connectivity. Our results also highlight the importance of including vegetation structure in primate censuses.

Riqueza, abundancia relativa y patrones de actividad de mamíferos medianos y grandes en el Bosque Protector Cerro Blanco (Guayas, Ecuador)

“…Las especies con mayor IAR fueron Dasyprocta punctata, Procyon cancrivorus, Odocoileus virginianus peruvianus y Leopardus pardalis, datos que concuerdan con otros estudios en el neotrópico (Hernández Hernández et al, 2018;Hernández-Pérez et al, 2015). Es posible que estas especies estén presentes en altas densidades poblacionales, por lo que se vuelven más fácilmente detectables con el presente esfuerzo de muestreo y con esta técnica (Cervera et al, 2015(Cervera et al, , 2016Espinosa et al, 2016).…”

Densidad poblacional y conservación de los primates de la Reserva de Biosfera del Noroeste, Tumbes, Perú

“…Additionally, in western Ecuador, after surveying 28 localities and only confirming the presence of C. a. aequatorialis in eight, density was calculated as 3.5 and 3.9 ind/km 2 (Albuja & Arcos 2007). In the Pacoche Marine and Wildlife Refuge, in the coast of Ecuador, Cervera et al (2015) recorded only three observations of C. a. aequatorialis outside 90 km of transects census, indicating a low population size and immediate need for conservation in Ecuadorian populations. With the low encounter rate we obtained added to the low-density estimates obtained through their distribution, this subspecies should be considered for priority conservation within the NBR.…”

“…Mantled Howler monkey's population density varied across its distribution range, representing low estimates in Colombia, 0.83 groups/10 km 2 (Ramirez-Orjuela & Sanchez-Dueñas 2005) and contrasting estimates in Tropical Dry Forest of Ecuador, from 47 ind/km 2 (Papworth & Mejia 2015) to 12.4 ind/km 2 (Cervera et al 2015). Again, these estimate differences can be attributed to the different methods used such as Triangulation surveys (Papworth and Mejia 2015), playback calls (Salcedo et al 2014), line transects and survey duration (Ramirez-Orjuela & Sanchez-Dueñas 2015, Cervera et al 2015), which makes difficult comparisons among areas and time. We recommend using line transects and distance sampling across this primate distribution to assess population changes and dynamics.…”

“…Considering the NBR is located in the limit of Ecuador and previous hunting attempts from Ecuadorians in the area of Campo Verde, an increased and continuous monitoring of this area is necessary to reduce the effects of illegal hunting. Furthermore, the lack of information about this species in Peru added to the low population density and connectivity of the remnant suitable areas in Ecuador (Albuja & Arcos 2007, Campos & Jack 2013, Cervera et al 2015 should give this species the higher legal protection by the Ministerio del Ambiente in Peru.…”