792 G. A. González‐Desales et al. TABLE 1 Records of the relative abundance index of Crocodylus acutus in Mexico during 1987–2012, from various sources, and in 2014. Locality, State Amela lagoon, Colima
Chamela-Cuixmala Biosphere Reserve, Jalisco Chiricahueto lagoon, Sinaloa
La Encrucijada, Biosphere Reserve, Chiapas El Verde estuary, Sinaloa Boca Negra estuary, Jalisco La Manzanilla estuary, Jalisco La Ventanilla estuary, Oaxaca Majahuas estuary, Jalisco Boca Negra estuary, Jalisco
Sumidero Canyon National Park, Chiapas Year
(not indicated) 1987–2003 1996 1996
1999–2000 1999–2002 1999–2002 2000–2001 2000–2002 2001 2001
Banco Chinchorro Biosphere Reserve, Quintana Roo 2003 La Palmita lagoon, Oaxaca San Blas estuary, Nayarit El Cajon reservoir, Nayarit Majahuas estuary, Jalisco San Juan lagoon, Jalisco Palmasola lagoon, Oaxaca
La Encrucijada, Biosphere Reserve, Chiapas 1Surveyed km, where known, are given in parentheses.
2004–2005 2005–2007 2010–2011 2010–2015 2010–2015 2012 2014
Relative abundance index1
45
20.57 6.94
2.1 (11.5) 45.4 (0.7)
40.9 (2.3) 47.3 (9.7) 5.2 (4.6)
Source Castillo (1996) García et al. (2010)
León-Ojeda et al. (1997) Martínez-Ibarra et al. (1997)
7.7 Navarro-Serment (2001) Huerta (2005) Huerta (2005)
Espinosa-Reyes & García-Grajales (2001) Huerta (2005)
18.25 (0.8) Cupul-Magaña et al. (2002) 2.8 (15) 6.8
Sigler (2010)
6.38 (4.9) 1.94 (14.8) 0.67 (15.2) 10.46 8.75
70.1 (0.6) 1.5 (28)
Charruau et al. (2005) Brandon-Pliego (2007)
Hernández-Hurtado et al. (2011) González (2013) Tello (2016) Tello (2016)
García-Grajales & Buenrostro-Silva (2014) This study
Mexico and locally in El Hueyate estuary in Chiapas? In addition, we examine the relationship of the number of negative incidents and presence records of C. acutus with socio-economic variables.
Methods
Negative interactions with C. acutus in Mexico Monthly records of negative interactions with C. acutus in Mexico, with geographical coordinates, were compiled from CrocBITE (2018) for 15 August 1993–8 June 2018. From the coordinates we calculated the Euclidean distances to the nearest nesting site (Casas-Andreu, 2003;Cedillo-Leal et al., 2013; Cupul-Magaña et al., 2004; Valtierra-Azotla, 2007; Charruau et al., 2010; Sigler, 2010; Charruau et al., 2011; Hernández-Hurtado et al., 2011; González-Desales et al., 2016a; Charruau et al., 2017) and to the nearest site for which relative abundance data were available (Table 1), using ArcGis 10.2 (Esri, Redlands, USA). The distance of in- teractions to nesting sites and the distance of interactions to sites where abundance of C. acutus had been evaluated were classified in intervals, based on the Rule of Sturges (Sturges, 1926). Using simple linear regression, we examined the rela- tionships between interaction frequency and proximity to nesting sites, relative abundance of crocodiles, and number of presence records of C. acutus up to 18 June 2018, (the latter from GBIF, 2017). A χ2 test was used to identify any association between interactions and the nesting season of C. acutus. We describe six socio-economic characteristics
of Mexican municipalities (INEGI, 2019) with records of negative interactions and the presence of crocodiles: (1) principal economic activity (as primary: agriculture, live- stock, forestry, hunting, fishing; secondary: mining, oil and gas extraction, manufacturing, electricity, water supply, construction; services: transport, government, other), (2) education level of males (mean years of study), (3) human population density (inhabitants/km2), (4)numberofmales in the population, (5) number of economically active males, and (6) municipality area (ha). We focused only on the characteristics of the male population, as negative inter- actions occur most frequently with them (García-Grajales & Buenrostro-Silva, 2019).
Human–crocodilian interactions in El Hueyate estuary
El Hueyate estuary in the La Encrucijada Biosphere Reserve on the Pacific coast of Chiapas state (Fig. 1) has two core areas (36,216 ha: El Palmarcito and La Encrucijada), and a 108,651 ha buffer zone (INE-SEMARNAP, 1999). Within the Reserve the caiman subspecies C. crocodilus chiapasius and C. acutus occur in both natural and anthropogenic ecosystems (dams, cattle ponds, fishery ponds and pampas; Sigler, 1996). There are 64 human settlements and 26,992 inhabitants in the Reserve, of which 28.5% do not receive school education of any level; the main economic activi- ties are fishing, agriculture and livestock breeding (INE- SEMARNAP, 1999). Reports indicate there are more crocodilians in the core zone than elsewhere (Sigler & Martínez-Ibarra, 1998;Peña, 2011) and nesting of both
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
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