Polynesian Tree Snail
Partula hyalina
Abstract
Polynesian Tree Snail Partula hyalina has most recently been assessed for The IUCN Red List of Threatened Species in 2023. Partula hyalina is listed as Vulnerable under criteria D2.
The Red List Assessment
Coote, T. & Gerlach, J. 2024. Partula hyalina. The IUCN Red List of Threatened Species 2024: e.T16313A119131673. Accessed on 13 December 2025.
Last assessed
19 December 2023
Scope of assessment
Global
The Green Status Assessment
Pearce-Kelly, P., Gerlach, J. & Aberdeen, S.
2024. Partula hyalina (Green Status assessment). The IUCN Red List of Threatened Species 2024: e.T16313A1631320252.
Accessed on 13 December 2025.
Population trend
Unknown
Number of mature individuals
Species recovery score
83% (81% - 83%)
Geographic range
-
Extant (resident)
-
Extant & Introduced (resident)
Assessment Information
Global Assessment
IUCN Red List Category and Criteria - Global Assessment
Vulnerable D2
Date assessed
19 December 2023
Year published
2024
Assessment Information in detail
Green Status Assessment Information
IUCN SPECIES RECOVERY CATEGORY
Species Recovery Score
83% (81% - 83%)
Date assessed
Year published
2024
Conservation impact metrics
Green Status Assessment Information in detail
Geographic Range
Native
Extant (resident)
French Polynesia (Society Is.)
Extant & Introduced (resident)
Cook Islands (Cook Is.)
Number of locations
1-5
Upper elevation limit
300 metres
Lower elevation limit
Geographic Range in detail
Indigenous and Expected Additional Range
Benchmark Year
1950
Expected Additional Range
No
Indigenous and Expected Additional Range in detail
Population
Current population trend
Number of mature individuals
Population severely fragmented
Continuing decline of mature individuals
Population in detail
Spatial Units
Spatial Units
Mangaia; Mauke; Raivavae; Rimatara; Rurutu; Tahiti; Tubuai
Number of Spatial Units
7
Spatial Units Definition Method
Biological
Spatial units description
This species is found across seven islands, covering three archipelagos (Lee et al. 2007). Since the species cannot disperse between islands, these form the basis for spatial units delineation.
Spatial Units in detail
Habitat and Ecology
System
Habitat type
Generation length (years)
Congregatory
Movement patterns
Continuing decline in area, extent and/or quality of habitat
Habitat and Ecology in detail
Ecological Function
Functionality description
It is difficult to directly measure if this species is carrying out its ecological functions. In such cases, where possible, pre-decline density would be used as a proxy for a Functional population. Historical data on population density of Partula spp. are limited, and there are no quantitative data prior to the 1960s. For this species, there are records from Murray and Johnson's field notes (1980s, pre-predator invasion), and survey data from seven valleys on Tahiti. This species was absent in two valleys surveyed, and the average density across the other five valleys was 2,457 per ha (with a range of 550–7,200). It is important to note that surveys will have been very targeted to sites with the species present, and distribution of this species is very localised.
In light of this, subpopulations are determined to be Functional if they reach the minimum density reported in historical surveys (550 individuals per ha).
Ecological Function in detail
Threats
Invasive and other problematic species, genes & diseases
- Invasive non-native/alien species/diseases
Threats in detail
Use and Trade
Use and Trade in detail
Conservation Actions
In-place research and monitoring
- Action Recovery Plan : Yes
- Systematic monitoring scheme : Yes
In-place land/water protection
- Conservation sites identified : Yes, over entire range
- Invasive species control or prevention : No
In-place species management
- Subject to ex-situ conservation : Yes
Conservation Actions in detail
Bibliography
Red List Bibliography
Green Status Bibliography
External Data
Images and External Links
Images and External Links in detail
CITES Legislation from Species+
Data source
The information below is from the Species+ website.
CITES Legislation from Species+ in detail
Ex situ data from Species360
Data source
The information below is from Species360's Zoological Information Management System (ZIMS)
Ex situ data from Species360 in detail
Studies and Actions from Conservation Evidence
Data source
The information below is from the Conservation Evidence website.