Population Viability Analysis of Howler Monkeys (Alouatta Palliata Mexicana) in a Highly Fragmented Landscape in Los Tuxtlas, Mexico

Abstract

We performed a population viability analysis (PVA) using a stochastic population model employing RAMAS/Metapop software: 1) to evaluate the contribution of demographic parameters to population growth, and 2) to simulate group trend and local extinction probability of the Mexican mantled howler monkeys Alouatta palliata mexicana in Los Tuxtlas, Mexico, under two landscape scenarios: isolated populations (IPS) and patchy population or metapopulation (MPS). We found that as the number of adult females per fragment increased, the rate of fecundity and relative reproductive success increased. As a consequence, the finite growth rate depended mainly on the survival of adult females. In both IPS and MPS the simulations suggested that the probability of extinction was exponentially dependent on fragment size. An estimation of 60% of extinction was predicted when fragment size is lower than 15 ha. Simulations suggest that in MPS the expected population change could be lower than in IPS. The value of these analyses for conservation of the primate populations studied is discussed. ResumenRealizamos análisis de viabilidad poblacional (PVA) usando modelos demográficos estocásticos con el programa RAMAS/Metapop para: 1) evaluar la contribución de parámetros demográficos en el crecimiento poblacional, y 2) simular la tendencia poblacional y probabilidad de extinción del mono aullador Alouatta palliata mexicana en Los Tuxtlas, México, bajo dos escenarios de paisaje: poblaciones asiladas (IPS) y poblaciones parchadas o metapoblación (MPS). Encontramos que conforme el número de hembras adultas por fragmento aumenta, la tasa de fecundidad y el éxito reproductivo también aumenta. Por lo tanto, la tasa finita de crecimiento poblacional depende principalmente de la sobrevivencia de las hembras. En ambos escenarios las simulaciones sugieren que la probabilidad de extinción depende exponencialmente del tamaño del fragmento. Se estimó una probabilidad del 60% de extinción cuando el tamaño de los fragmentos es menor a 15 ha. Las simulaciones sugieren que en el MPS el cambio es menor en comparación al IPS. Se discute al valor de este tipo de análisis para la conservación de las poblaciones de primates investigadas.

Biological Correlates of Extinction and Persistence of Primates in Small Forest Fragments: A Global Analysis

“…All the species in the fragments are extinction-prone. Other workers, using other approaches, have also suggested that all species will go extinct in fragments as small as the majority in which studies of effects of fragmentation are usually conducted [9,[33][34][35][36][37][38][39]. The fragments are in extinction debt [40].…”

The Impacts of Population Subdivision on the Viability of Brachyteles hypoxanthus

“…In another PVA model, dispersal was not detrimental to the persistence of a small Alouatta palliata mexicana population (approx. 75 individuals) in a fragmented landscape with fragments ranging from 15 to 60 ha [Mandujano and Escobedo-Morales, 2008]. However, we observed detrimental effects for B. hypoxanthus , suggesting this process may also affect medium and large mammals.…”

The Woolly Monkey

“…In our particular case for this population of woolly monkeys, the population parameter that contributed the most to population growth is adult female survival. Several population growth studies in primates have found similar patterns, where survival and fecundity of adult females are the most important factors determining the population growth: muriqui monkeys , howler monkeys (Mandujano and Escobedo-Morales 2008), baboons (Alberts and Altmann 2003), and tarsiers (Neri-Arboleda 2010). Another study with ateline monkeys ( Brachyteles) has also found a relevant role of female fertility on population growth and differences in mortality rates between age and sex classes (Strier and Ives 2012).…”