Factors influencing the occurrence of negative interactions between people and crocodilians in Mexico


GIO VA N Y ARTURO GONZÁL E Z-DES ALES,LUIS S IGLER ,J ESÚS GAR CÍA-GRAJALES P IERRE CHARRUAU,MARTHA MAR I E L A ZARCO-GONZÁL E Z ÁNGE L B AL BUENA -SERRANO and OCT A V IO MONR O Y-VILCHI S


Abstract Negative interactions between people and croco- dilians have increased worldwide, but in Mexico there have been few systematic reports and no rigorous evaluation of this problem. We compiled information on negative interactions between people and the spectacled caiman Caiman crocodilus and American crocodile Crocodylus acutus from the Worldwide Crocodilian Attack Database for 1993–2018, and we investigated interactions in greater depth, through interviews with people in La Encrucijada Biosphere Reserve. We examined the relationship between the occurrence of negative interactions between people and C. acutus and the species’ nesting season and abun- dance, and presence records. In Mexico, the frequency of negative interactions increases when anthropogenic activ- ities occur close to nesting sites (,30 km) and during the nesting season (February–September). In La Encrucijada, following negative interactions with crocodiles, the local inhabitants killed 30 crocodiles measuring .2.5m long in 2011–2012. The frequency of negative human–crocodilian interactions was not correlated with the abundance of cro- codilians but was correlated with the number of presence re- cords of crocodiles. Strategies to minimize these interactions include warnings at nesting sites, increased monitoring of anthropogenic activities during the nesting season, and management of nests to prevent them being destroyed by people.


Keywords Caiman crocodilus, crocodile, Crocodylus acutus, human activities, human–crocodile conflict, Mexico, nesting, relative abundance


Introduction


caiman Caiman crocodilus, and two species of the family Crocodylidae, the American crocodile Crocodylus acutus and Morelet’s crocodile Crocodylus moreletii occur in Mex- ico. On the IUCN Red List C. crocodilus and C. moreletii are categorized as Least Concern and C. acutus as Vulnerable (Cedeño-Vázquez et al., 2012; Ponce-Campos et al., 2012; Balaguera-Reina & Velasco, 2019), and in Mexico the three species are subject to Special Protection (SEMARNAT, 2010). Populations of C. acutus and C. crocodilus were severely affected by hunting for their skins until this was permanently banned in the 1970s. Since then the populations of the three species have increased, although in some regions of Mexico they are still exploited (INE-SEMARNAP, 1999; Aguilar-Galindo, 2005). As a result of this recovery of crocodilian populations,


O


GIOVANY ARTURO GONZÁLEZ-DESALES,MARTHA MARIELA ZARCO-GONZÁLEZ,ÁNGEL BALBUENA-SERRANO and OCTAVIO MONROY-VILCHIS (Corresponding author) Centro de Investigación en Ciencias Biológicas Aplicadas, Universidad Autónoma del Estado de México, Instituto Literario 100, Col. Centro, C.P. 50000 Toluca, Estado de México, Mexico E-mail tavomonroyvilchis@gmail.com


LUIS SIGLER The Dallas World Aquarium, Dallas, USA


JESÚS GARCÍA-GRAJALES Universidad del Mar Campus Puerto Escondido, San Pedro Mixtepec, Oaxaca, Mexico


PIERRE CHARRUAU Centro del Cambio Global y la Sustentabilidad A.C. Calle Centenario del Instituto Juárez s/n, Villahermosa, Tabasco, Mexico


Received 7 August 2018. Revision requested 30 October 2018. Accepted 4 June 2019. First published online 21 May 2021.


and because of land-use change, flooding, human popu- lation growth and feeding of crocodiles by people, negative interactions between people and crocodiles have escalated (García-Grajales, 2013). Crocodile behaviour, such as terri- torial and self defence, and nest protection by females, exacerbate these negative interactions (Pooley et al., 1989; García-Grajales & Buenrostro-Silva, 2018). In the Americas, C. acutus and C. moreletii have been involved in a number of fatal incidents, with 2.9 and 0.5 cases/year, respectively (Sideleau, 2015). Such incidents are not, however, always recorded (Aust et al., 2009). Systematic compilation of data on interactions between people and crocodilians is re- quired to identify the potential risks to people from croco- diles, and to avoid retaliatory killings (Caldicott et al., 2005). In the state of Chiapas in Mexico negative interactions


between crocodiles and people could be expected, as all three species occur there, but in the Worldwide Crocodilian Attack Database (CrocBITE, 2018) only four incidents have been recorded in this state, which is probably an under- estimate. Here we examine the following questions: (1)Does the frequency of negative human–crocodilian interactions increase during the nesting season? (2) Does the frequency of incidents increase when there is human habitation within nesting areas? (3) Does the frequency of such interactions increase with crocodile abundance, both nationally in


This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. Oryx, 2021, 55(5), 791–799 © The Author(s), 2021. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319000668


fthe 24 species of crocodilians (Uetz et al., 2016), one species of the family Alligatoridae, the spectacled


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164