The Bahama Boa, Chilabothrus strigilatus, was first described in 1862. However, even almost 160 years after it’s first description, the ecology of this boa still holds many facts that are unknown to science.
The team of Sebastian Hoefer and colleagues were interested in several biological aspects of the snakes occurring on Eleuthera Island. In their recent study they investigated two snake species occurring on Eleuthera Island and compared prey as well as endoparasite prevalence in the snakes .
Eleuthera Island is one of several islands and cays where Chilabothrus strigilatus occurs. Eleuthera Island has a surface area of 457 km2, maximum elevation of 60 meters above sea level, is 120 km long and, in places, 1 km wide. Eleuthera Island is located on the eastern part of the Great Bahama Bank.
The study took place from 19 August 2019 to 16 March 2020. The researchers took the approach to collect road killed specimens of the snakes on Eleuthera and investigate stomach contents as well as parasite load. This approach is unique and offers detailed insights without sacrificing healthy snakes.
The team investigated across four habitat types and the road was investigated up to four times daily by car or bike. As a result, the researchers collected 270 road killed snakes representing all four species (232 Bahamian Racers, 31 Bahamian Boas, 6 Northern Bahamas Tropidophis, and 1 Cuban Brown Blindsnake) occurring across Eleuthera. During this seven-month period, road killed snakes amounted to 35.5 snakes per month or 1.2 a day. For Bahamian Boas, this translated to 5.2 road kills per month. Road mortality was previously studied on another Bahamian boa species, Chilabothrus exsul on Abaco Island . The study concluded that on Abaco island 1.6 Boas are lost per week due to road mortality. This amounts to a total of 83.2 Boas per year. The data of Hoefer and colleagues amounts to an annual loss of 62.4 boas. Thus road mortality and increased traffic poses a serious threat to at least two Bahamian boa species.
The main aim of the study however was the prey selection and parasite load. The Bahamian Racer Cubophis vudii vudii feeds predominantly on lizards (Anolis sp.). However, they found the Racers to be opportunistic generalists and in addition to documenting oophagy for the first time in any Bahamian snake, they also described two snakes, Tropidophis canus barbouri and Typhlops lumbricalis, as prey items of the Racer.
In contrast, the diet of Bahamian Boas consisted exclusively of of anoles and rats. Juvenile boas fed exclusively on anoles and adults consumed only rats. This finding confirms an ontogenetic shift in the feeding ecology of the Bahamian Boa.
Regarding the endoparasite load, it was interesting that nematodes were found in most of the racers but none of the boas. One explanation for this observation is that sample size was different in Boas and Racers but this could also be attributable to differences in activity, movement patterns and foraging behavior between the species.
More information on Bahamas boas can be found here.