DOI: 10.5281/zenodo.6629178
title: Invasive snakes on islands: dataset and species vignettes

description: This dataset describes known introductions of snakes to islands outside of their respective historical, native ranges as of May, 2022. It was created during the preparation of the chapter "Welcome to paradise: snake invasions on islands" for the upcoming book <em>Islands and Snakes</em>, Vol. II. Details for this accompanying summary text will be provided upon final publication. It contains a spreadsheet/database of individual documented introductions (Island_Snakes_data_cleaned), and vignettes organized by species that summarize introductions and provide references. <em><strong>Island_Snakes_data_cleaned Database Details</strong></em> The database contains several categories of information; categories are listed in bold below. <strong>General Introduction information</strong> Introduced Country = the country authority over the geographic location of introduction event Introduced to Island = the name of the island where a snake was introduced Island Group Name = the name of the island grouping, if any exists Introduced Ocean of Sea = the name of the body(ies) of water surrounding the island where a snake was introduced Native Range = a general description of where the snake is native to, if known Date Introduced Note = any details in addition to the year provided in Date Introduced column Date Introduced = the date a snake was considered or recorded as introduced to an island. These dates are often approximate of based on year of publication. Established = a binary variable where 1 indicates a snake has established a population on that island, and 0 indicates it has not established or there is not enough evidence to determine this status. Currently Present on island = a binary variable where 1 indicates a snake is present on that island, and 0 indicates it is not present or there is not enough evidence to determine this status. <strong>Pathway information - </strong>these variables describe known pathways of introduction to an island. All variables are binary; 1 indicates the pathway likely contributed to the introduction of the snake, 0 indicates it likely did not or there is not evidence to support that pathway. Nursery Trade - introduced as a result of nursery or plant trade Cargo - introduced as a result of cargo that is not specifically associated with nursery or plant trade Pet Trade - introduced as a result of importation for eventual keeping as a pet or in captive hobby herpetoculture, or escape Intentional - introduced intentionally to the wild by a person intending to establish a population or releasing an animal for non-religious purposes Industrial - introduced as a result of an industry not described in other pathways; e.g. entertainment industry, skin trade Research - introduced as a result of escape or release from captive animals used for research purposes Medicinal - introduced as a result of medicinal trade in animals Food - introduced as a result animals traded or imported for consumption Pathway comment - additional details about the pathway associated with the introduction event <strong>Introduced island characteristics - </strong>attributes of the ecology and geography where snakes have been introduced. Binary variables 1 indicate there is evidence for the category, 0 indicates there is not evidence for that category. *Note*: we did not consider fully-aquatic sea-snakes in our determination of island ecology characteristics introduced to historically snake-free - 1 indicates that prior to the snake's introduction, no other snakes were present on the island. introduced to island with native snakes already there - 1 indicates that prior to the snake's introduction, native snakes were already present introduced to island with ecologically similar snake - 1 indicates that prior to the snake's introduction, a snake with similar ecotype was already present (native or non-native). introduced island with same family - 1 indicates that prior to the snake's introduction, another snake of the same family was already present (native or non-native). introduced island with same genus - 1 indicates that prior to the snake's introduction, another snake of the same genus was already present (native or non-native). island area km2 - a rough estimate of the island's total geographic area in km<sup>2</sup> nearest large landmass (&gt;10000km2) - the name of the nearest landmass (greater than 10,000 km<sup>2 </sup>in area) to the island where a snake was introduced (as determined by linear distance). distance to nearest large landmass/mainland (km) - an estimate of the linear distance from the island where a snake was introduced to the nearest landmass greater than 10,000 km<sup>2 </sup> in area. distance to native origin (rough km) - a rough estimate of the linear distance from the snake's native range (and source of non-native introduction, if known) to the island where the snake has been introduced. Native_to_nearest_large_landmass - a binary variable where 1 indicates the snake is native to the nearest large landmass names in the nearest large landmass (&gt;10000km2) column. island status comment - any additional information about the ecology of geography of the island where a snake was introduced. <strong>Snake characteristics - </strong>Attributes associated with the ecotype and diet of the snakes introduced to islands. Binary variables indicate whether there is evidence to support a snake's membership to a specific category. Constrictor - 1 indicates the snake can be classified as a constrictor- using strangulation and squeezing to subdue prey. Venomous - 1 indicates the snake can be classified as venomous. Fossorial - 1 indicates the snake can be classified as fossorial; dwelling on ground in soil or leaf litter Terrestrial - 1 indicates the snake can be classified as terrestrial; living on the ground but generally not in soil or leaf litter Aquatic - 1 indicates the snake can be classified as aquatic, living at the water's edge or near the water. Arboreal - 1 indicates the snake can be classified as arboreal; living mostly in trees Cave-dwelling (troglodytic) - 1 indicates the snake can be classified as Cave-dwelling or troglodytic max SVL in mm (estimate) - the maximum snout-to-vent length recorded for the introduced snake species; this information may be derived from either native or introduced ranges Generalist - 1 indicates the snake can be classified as having a generalist diet Specialist - 1 indicates the snake can be classified as having a specialist diet Mammals - 1 indicates the snake is documented as consuming mammals Birds - 1 indicates the snake is documented as consuming birds Amphibs - 1 indicates the snake is documented as consuming amphibians Reptiles - 1 indicates the snake is documented as consuming reptiles Inverts - 1 indicates the snake is documented as consuming invertebrates <strong>Impacts of introduction - </strong> a summary of any documented impacts associated with the introduction of the snake to the island. Ecological Impacts - 1 indicates there is documentation to support an impact of the snake's introduction to the island's ecology Health Impacts - 1 indicates there is documentation to support an impact of the snake's introduction to human health on the island Economic Impacts - 1 indicates there is documentation to support an impact of the snake's introduction to the local economy of the island Impacts not measured - 1 indicates there is no formal documentation of impacts of the snake to any of the previous categories Impact Comment - any details about impacts, or speculated impacts <strong>Management </strong> Previous eradication Efforts - 1 indicates there have been measures taken in the past to attempt to remove the snake species from the island Current eradication effort - 1 indicates that as of May 2022, attempts to remove the snake species from the island are ongoing. Cool Stuff! -<strong> </strong>a category with comments on introductions that do not fit neatly elsewhere <em><strong>Vignette details</strong></em> Vignettes are organized by species, using the most up-to-date accepted species name according to the Reptile Database in May, 2022. The vignette describes documented introductions to islands, which includes multiple locations for some species. All vignettes follow a similar format. <em>Species name</em> and any relevant synonyms or colloquial names are given.<br> <em>Where native</em>- describes the native range of the snake, if known.<br> <em>Where introduced, when </em>- describes the islands where a snake has been documented as introduced, and the associated dates of introduction (if they differ from the publication date) <em>Introduced Island characteristics - </em>gives any relevant information about the ecology or geography of the island(s) where the species has been introduced <em>Pathways of introduction </em>- gives information about pathway(s) relevant to introductions <em>Why successful introduction </em>- if the introduction was successful (i.e. established), what factors may have played a role in this success <em>Any failed island introductions elsewhere, why?</em> - If introductions are recorded as not established or failed, any information that may help understand the failure of the introduction to establish. <em>Documented impacts of introduction (Ecological, Economic, Social, Human Health)</em> - any impacts documented from the introduction of the species to the island(s) <em>Speculated impacts</em> - any potential impacts of the species' introduction to the island(s), whether unrecorded, unexamined, or estimated to have a lag time before apparent <em>References - </em>References cited within the vignette