Road surveys of the invasive Red-tailed Boa (Boa constrictor) in the North-west region of Puerto Rico.

The monitoring of invasive species has always been a priority of both local and federal environmental agencies. Yet, some species, such as the Red-tailed Boa (Boa constrictor), have proven difficult to survey due to their cryptic behavior. Therefore, road surveying could prove to be a less-expensive method to reliably monitor the activity and distribution of exotic invasive species in Puerto Rico, while also reducing the amount of effort required to obtain this type of data. For our research, we quantified road mortality on a single transect passing through 4 municipalities on the north-west region of Puerto Rico (San Sebastián, Añasco, Las Marías and Mayagüez). The transect was surveyed 132 times during the sampling period between May 2018 and March 2019. We were able to find a total of 47 Red-tailed boas over 3,960 km of transect sampling. This represented an encounter rate of 0.012 boas/km, and an average of 0.011 dead boas per km and 0.326 dead boas per survey. We were also able to observe that, even though the distribution of the Red-tailed Boa reached as far north as the municipality of San Sebastian, the largest concentration of this species was in, or close to, the Municipality of Mayagüez.

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