Jordan Cissell of the University of Alabama recently published his study “Human Landscape Modification in Placencia, Stann Creek District, Belize: Possible Implications for Crocodile Hybridization” in the Journal of Latin American Geography. In 2017, Jordan surveyed land in the Placencia Lagoon area and discussed crocodile research findings with Dr. Marisa Tellez of the Crocodile Research Coalition. Using field observations and satellite images, Jordan was able to build a composite of the habitat into 6 different categories: a) mangrove forest; b) agriculture; c) evergreen broadleaf forest; d) aquaculture; e) savanna; and f) built up land. He then compared his findings to data collected in the same areas from data collected 1976. Over four decades, there was significant loss of mangrove, litoral, broadleaf forests, as well as savannas. All being converted to built-up land and develop aquaculture and agriculture facilities. While water management on aquaculture facilities offer refuge for crocodiles threatened by other habitat destruction, they also provide artificially concentrated habitat which may result in more hybridization between the American and Morelet’s crocodiles.
Below, you will find his abstract:
Habitat destruction and degradation represent the most significant contemporary threats to populations of American crocodiles (Crocodylus acutus) and Morelet’s crocodiles (Crocodylus moreletii) throughout their respective ranges. In addition to destroying nesting sites, escalating inter- and intra-specific competition, and increasing instances of human-crocodile conflict, it has been suggested that habitat decline may also be contributing to recent hybridization that could threaten each species’ genetic integrity. In this paper, we use the Placencia Peninsula in southern Belize as a case study, synthesizing remote-sensing based quantification of historical land use / land cover (LULC) change in the study area with insights from literature to demonstrate the potential role of LULC change as a driver of crocodile hybridization in the area. Using visual interpretation and supervised classification of satellite imagery, we found that, between 1976 and 2017, built-up land, agriculture, and aqua-culture expanded dramatically in the study area at the expense of mangrove and litoral forests, evergreen broadleaf forests, and savanna. The widespread conversion of traditional crocodile habitat to anthropogenic and uses likely increased the concentration of suitable American and Morelet’s crocodile habitat within a diminished sympatric zone, making Placencia’s increasingly human-modified landscape more conducive to crocodile hybridization in 2017 than it was four decades prior. With similar landscape conversions taking place throughout the crocodiles’ overlapping zones in North and Central America, hybridization may soon represent an increasingly substantial threat to both species’ conservation statuses.
Cissel, J.R., and M.K. Steinberg (2020) Human landscape modification in Placencia, Stann Creek District, Belize: possible implications for crocodile hybridization. Journal of Latin American Geography 19(2): 218 – 242.