Landscape Characteristics Associated With Demographic Attributes of Alouatta caraya Howler Monkeys in the Argentine...

Deforestation, habitat loss, and fragmentation impact the ecology, genetics, and health of many wildlife species, including primate populations. We evaluated the association between landscape characteristics and demographic features of Alouatta caraya howler monkeys in human-modified rural areas of Pampa del Indio in the Argentine humid Chaco. Landscape metrics were obtained from a supervised classification of a Landsat 8 image based on different kinds of exploited forests. Four times over a 2-year period, we surveyed howler monkey groups using loud calls heard at 113 listening posts in three habitat types: gallery woodland, riparian, and quebrachal hardwood forests. We also determined the age and sex composition of 31 groups through observation. A Bayesian spatial generalized linear mixed model using Integrated Nested Laplace Approximation with a Stochastic Partial Differential Equation to account for spatial dependence revealed a negative association between howler monkey group counts and prime habitat availability (i.e., old-growth forest). Howler group size was positively associated with patch density, while both the immature-to-adult female ratio and group size were negatively associated with the division index of prime habitat. Despite the apparent ability of howler monkeys to cope with habitat modification, prime habitat availability is crucial to the long-term conservation of A. caraya. Innovative landscape management strategies are required to ensure the long-term persistence of howler monkeys in human-modified environments under rapid change in the Gran Chaco eco-region.