reptiles

Hurricane Effects on Critically Endangered Reptiles

Caribbean flora and fauna have always coped with the destructive forces of hurricanes. However, climate change leading to an increase in their frequency and strength, and because many species have declined in abundance due to anthropogenic causes, a better understanding of how hurricanes effect local populations is essential.

The Quill before and after Hurricane Irma. Photo credit: Hannah Madden

2017 Hurricane Season

The 2017 Caribbean hurricane season was the most intense recorded to date. Both Irma and Maria, category-5 hurricanes, closely passed Sint Eustatius and caused major destruction on the island; reported in this Nature Today article. Although immediately after the storms it was clear that trees were heavily affected and mostly defoliated, understanding which species were affected and to what extent requires time for data collection and comparison. Since 2017, several studies have provided pieces of information in order to understand how local populations coped, or not, with the 2017 hurricane season.

Since 2017, researchers found that >90% of all trees were defoliated by more than ¾, and that especially trees at higher elevations (such as on the Quill volcano) were affected more severely. Another study that focused on the Bridled Quail-dove (Geotrygon mystacea), demonstrated that the population declined by 77% in 2019 compared to pre-hurricane levels. A follow-up study in 2021 (not yet published) recorded a further decline to just 125 individuals, and the Bridled Quail-dove will likely be re-assessed by the IUCN.

Reptiles

Focusing on reptile species, a novel study further aids our understanding of the ecosystem-wide impact that the 2017-hurricane season had on Statian biodiversity:

The new study, focusing on the Critically Endangered Lesser Antillean iguana (Iguana delicatissima), shows that its population decreased by at least 20% during 2017. Comparing sighting and survey data from 2017–2018, the authors found a decrease in both the occupancy and population size of the iguana species. Importantly, no recovery was observed in 2019, suggesting that this already small population needs multiple consecutive years without major hurricanes to recover. Interestingly, similar to Statia’s forests, iguanas at higher elevations were found to have been affected more severely.

 

Letter Antillean Iguana. Photo credit: Philippa King

Importance

Small islands such as Sint Eustatius are home to declining populations of rare and endangered species. In many cases, these isolated populations are unable to migrate between islands and thus populations can only increase in size locally. These new studies highlight the need to improve habitat quality and lower anthropogenic threats to optimize the natural recovery of these species. Ideally, at least for population increase could be aided by a local head-starting project where baby iguanas are nourished in temporary captivity and released once they are larger and more likely to survive.

You can find the full study here entitled “Hurricane-induced population decrease in a Critically Endangered long-lived reptile” using the DCBD link below.

 

 

More info in the Dutch Caribbean Biodiversity Database
 

Downloads & links >

 

Published in BioNews 54

Date
2022
Data type
Media
Theme
Research and monitoring
Geographic location
St. Eustatius

Forensic Genetic Analyses of Melanistic Iguanas Highlight the Need to Monitor the Iguanid Trade

Simple Summary: The illegal pet trade remains an ongoing, substantial threat to wild populations,
especially small insular populations, and can even lead to extinction. Fraudulent activity within the
global reptile trade is known to occur, but its identification through forensic applications depends
on knowledge of diversity within wild populations. In this study, we assessed the geographic origin
of melanistic iguanas (Iguana iguana), which are only found in nations that have never authorized
legal export of live animals. Analysis of genetic data from two pet iguanas in the USA flag these as
originating from Saba or Montserrat, from which no export permits have ever been issued, confirming
their illegal origin. Despite the international trade in I. iguana, in which tens‐ if not hundreds of
thousands of specimens are traded each year, only a handful of individuals have been genetically
assessed. Our work highlights the utility of applying forensic genetic techniques to this trade in
order to track and discourage illegal activity.

Abstract: Lizards within the Iguana iguana species complex are among the most common reptilian
pets, with the widest natural geographic range among iguanids. Deep phylogenetic divergence distinguishes
multiple mitochondrial clades, and several taxonomic changes have recently been proposed.
These small populations, typically island endemics, are threatened by numerous factors, including
the international pet trade. Recent investigations reveal the absence of required CITES permits
for lawful export of animals, providing evidence of ongoing illegal trade. Additional monitoring
of trade in iguanas can be achieved through the application of forensic molecular techniques. In
this study, two captive melanistic iguanas were genotyped for molecular markers for which geographic
distributions of alleles have been established. Mitochondrial sequencing indicates that both
animals carry a haplotype known to originate from the islands of Saba and Montserrat, populations
taxonomically proposed to be Iguana melanoderma. Genotypes at 15 microsatellite loci are equally
consistent with this origin, given the results of a principal component analysis. This first forensic
genetic assessment within the extensive I. iguana pet trade highlights the presence of illegal activity.
The need for additional forensic assessments of pet‐trade iguanas is evident, especially given that
their value is driven by variety and rarity, which is further intensified by recent taxonomic changes.

Date
2022
Data type
Scientific article
Theme
Research and monitoring
Journal
Geographic location
Saba