A demographic history of a population of howler monkeys (Alouatta palliata) living in a fragmented landscape in Mexico.

Jurgi Cristóbal Azkarate,Joaquim Veà Baró,Jacob C Dunn,Cristina Domingo Balcells

doi:10.7717/peerj.3547

Jurgi Cristóbal Azkarate, Joaquim Veà Baró + Show 2 more

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https://doi.org/10.7717/peerj.3547

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Abstract

Long-term field studies are critical for our understanding of animal life history and the processes driving changes in demography. Here, we present long-term demographic data for the northernmost population of mantled howler monkeys (Alouatta palliata) residing in a highly anthropogenically fragmented landscape in Los Tuxtlas, Mexico. We carried out 454 monthly group visits to 10 groups of mantled howler monkeys between 2000 and 2011. The population remained relatively stable over the 11-year study period, with an overall increase in the total number of individuals. Birth rates and inter-birth intervals were comparable to those of howler monkeys at non-fragmented sites, suggesting that living in a fragmented landscape did not affect the reproductive output of our study population. Moreover, despite the landscape, dispersal events were commonplace, including many secondary dispersals (individuals emigrating from groups that they had previously immigrated into). Finally, we found a marked effect of seasonality on the dynamics of our study population. In particular, the period of lowest temperatures and resource scarcity between November and March was associated with higher mortality and reproductive inhibition, while the period of resource abundance between April and May was associated with the majority of conceptions and weaning of offspring. This, in turn, could be influencing dispersal patterns in our study area, as male howler monkeys seem to time some of their immigrations into new groups to coincide with the start of the period of higher fertility, while females preferentially joined new groups several months before the onset of this period. These data have important implications for the conservation and management of howler monkeys in fragmented landscapes, as well as for our understanding of the effect of seasonality over howler monkey dispersal, reproduction and survival.

Highlights

Long-term field studies of primates, i.e., studies that cover at least an important proportion of individual life cycles, are critical for our understanding of life history and the processesHow to cite this article Cristóbal Azkarate et al (2017), A demographic history of a population of howler monkeys (Alouatta palliata) living in a fragmented landscape in Mexico
Given that demographic patterns are contingent on local climate and vegetation, a comprehensive understanding of the factors determining dispersal processes, mortality and fertility of primates requires long-term studies to be conducted in different taxa, and in different landscapes and locations
For the calculation of the seasonality of demographic events, inter-birth interval (IBI) and birth rates, we considered only those events that were registered during periods in which the study groups were observed continuously and that could be assigned to a date with a maximum error of one month

Summary

Introduction

Long-term field studies of primates, i.e., studies that cover at least an important proportion of individual life cycles, are critical for our understanding of life history and the processesHow to cite this article Cristóbal Azkarate et al (2017), A demographic history of a population of howler monkeys (Alouatta palliata) living in a fragmented landscape in Mexico. Given that demographic patterns are contingent on local climate and vegetation, a comprehensive understanding of the factors determining dispersal processes, mortality and fertility of primates requires long-term studies to be conducted in different taxa, and in different landscapes and locations. Such studies are important in modified habitats, where monitoring demographic parameters in threatened populations may be critical for primate conservation. Long-term data on howler monkey (Alouatta spp.) demography is limited to studies of red howler monkeys in Venezuela (A. arctoidea) (Crockett & Rudran, 1987; Rudran & Fernandez-Duque, 2003), mantled howler monkeys in Panama (A. palliata aequatorialis) (Milton, 1982; Milton, 1990; Milton, 1996) and Costa Rica (A. p. palliata) (Glander, 1992; Clarke et al, 2002; Zucker & Clarke, 2003; Clarke & Glander, 2010), black and gold howler monkeys (A. caraya) in Argentina (Kowalewski & Zunino, 2004; Zunino et al, 2007), and Central American black howler monkeys (A. pigra) in Mexico (Dias et al, 2015)

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