794 G. A. González‐Desales et al.


FIG. 2 Negative interactions by month involving C. acutus in Mexico, showing that the incidents are more frequent in nesting season.


during 2005–2014 (Fig. 3b). Two of the incidents were fatal, two resulted in major injury (limb loss or permanent motor impairment) and two resulted in minor injury. Five of the incidents involved C. acutus and one C. crocodilus chiapa- sius (Table 2). According to the interviewees, incidents between croco-


diles and domestic animals (mainly dogs) and livestock (cattle and pigs) are common in the area. Following nega- tive interactions with crocodiles, 30 adult crocodiles were hunted by the inhabitants of the three settlements during 2011–2012. Five of the six negative interactions recorded occurred close to nesting sites (Table 2), where we observed 34 nests of C. acutus and 19 of C. crocodilus chiapasius in 2014 (Fig. 1; González-Desales et al., 2016a,b).


Discussion


As far as we are aware, this study is the first analysis of the potential causes of the negative interactions between people and C. acutus in Mexico, and the first standardized report of populations trends of C. crocodilus chiapasius and C. acutus in a coastal region of Chiapas. For Crocodylus porosus, in Australia and Sri Lanka, abundance and protection of the nest by females are the main factors that increase the prob- ability of negative interactions with people (Caldicott et al., 2005; Amarasinghe et al., 2015). Our study suggests, how- ever, that the abundance of C. acutus does not influence the frequency of incidents in Mexico. The surveymethod used for the calculation of the relative


abundance index is potentially subject to biases (García- Grajales et al., 2007) and therefore the lower relative abundance we detected in La Encrucijada in 2014 cannot necessarily be attributed to the illegal killing of crocodiles.


FIG. 3 (a) Relative abundance index (crocodilians observed per km, during 1997–2014)of C. acutus and C. crocodilus chiapasius, and (b) the number of negative human–crocodilian interactions per year (during 2005–2018), in El Hueyate estuary, La Encrucijada Biosphere Reserve, Mexico.


However, with illegal killings as high as 30 individual croco- diles per incident (according to the people we interviewed), such killings would be expected to affect abundance, especially if any of the crocodiles killed are reproductive females. A similar situation occurs in other regions of Mexico. Hernández-Hurtado et al. (2006) reported 11 negative incidents during 1993–2004 in the Western Pa- cific region, following which 155 crocodiles were hunted, injured or captured, of which 40 were hunted in Manzanilla, Jalisco. The illegal killing of crocodiles has been reported elsewhere after negative interactions, such as with C. porosus in Sri Lanka (Amarasinghe et al., 2015). Following negative interactions between C. acutus


and people in La Encrucijada, there was an apparent decrease in abundance of the species, to a level similar to that recorded when protection of the species began in this


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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