Will the introduced boa hurt cascabel populations on Aruba?

Has the introduced Boa constrictor negatively impacted the unique Arubian Cascabel?  Will the boa out compete the cascabel for food and other resources?  Will the boa cause the extinction of the cascabel?  These questions are the emphasis for a three year program to study the health of the cascabel population on Aruba.  R. Andrew Odum from the Toledo Zoo, Diego Marquez from Fundacion Parke Nacional Arikok, Howard Reinert from the  College of New Jersey, and  William Lutterschmidt from Sam Houston State University are working to measure the current physical condition cascabels so that these data can be compared to previous data collected prior to the establishment of the Boa.   


 Project Abstract:

Most studies to assess the impact of introduced species to native fauna have been undertaken after there is a substantial decline to local populations because these declines are often slow processes and are difficult to recognize  until population numbers are greatly reduced.  This is especially true for secretive species that have low population densities and when the introduced species is a direct competitor for resources to the resident species.  This lack of early detection ability results in delayed intervention, which results in less effective recovery programs, loss of gene diversity, and increased monetary costs.  By monitoring a condition index (CI) for the rattlesnake, this project will monitor the impact of the introduced boa constrictor (Boa constrictor) on the native Aruba Island rattlesnake (Crotalus unicolor) before its population numbers decline.  CI has been correlated to energy reserves available to the animal and is thus an indicator of individual animal fitness.  Boa constrictor is a generalist that utilizes some of the same food resources with C. unicolor.  The introduction boa has negatively impacted other insular ecosystems. This study will compare CI of rattlesnakes in four separate marine terrace sites with varying densities of boas.  Comparisons will also be made to data previously acquired from earlier rattlesnake studies performed prior to the establishment of the boa on the island (1994-2000).   A general decrease in CI for C. unicolor is considered an indicator of population stress and potential decline.  This knowledge could then be used to develop proactive methodologies for the rattlesnake’s conservation before their numbers are reduced, which could include captive propagation and release.

Injecting a passive intergrated trasnponder


This conservation project is supported by the Toledo Zoological Society, Arikok National Park, San Diego Zoological Society, College of New Jersey, and Sam Houston State University .