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Taxon overview

Taxonomy and taxon overview

One of the main objectives of Balearica is to compile a comprehensive checklist of species living in Balearic ecosystems. To achieve this, we aggregate data on a wide range of taxa from sources, including Bioatles1, Global Biodiversity Information Facility2, Catalogue of Life3, National Center for Biotechnology Information - GenBank45, Barcode of Life Data Systems - BOLDSystem6, scientific and grey literature, that document species occurrences in the region. As with any large-scale biodiversity database, this platform is continuously evolving. We are actively reviewing the taxon nomenclature and incorporating newly recorded species. However, given the vast scope of platform, some taxa may still be missing. If you identify any gaps or inconsistencies, we encourage you to contact us, so we can address and improve the dataset accordingly.

Taxonomy review

The nomenclature of each taxon has been mainly cross-referenced with the Catalogue of Life (CoL)3 database to ensure accuracy and consistency across the platform. If a species is not listed in the CoL, we use information from other trusted sources to keep the data accurate and reliable. The source(s) of a specific taxonomic level are displayed beneath each taxon name on the Overview page for transparency and connect with other databases (Figure 1).

Warning

The taxon nomenclature has been cross-referenced with Catalogue of Life Release 9923 (2023-08-17). New releases may update taxon IDs, so if a link to the Catalogue of Life is broken, please contact us, so we can resolve the issue. We are also working on a new pipeline to regularly update taxon IDs to improve service quality.


Fig1
Fig.1 Taxonomic sources

Taxonomy levels

Limited to the domain of Eukaryote, taxonomy in Balearica includes 10 taxonomic levels: Life, Kingdom, Phylum, Class, Order, Family, Genus, Species, Subspecies, and Variety.

These levels were chosen to keep things simple while still being broad enough to categorize effectively. It is important to note that this platform was not specifically designed for taxonomic classification and is not a specialized tool created by or exclusively for taxonomists. Its primary purpose is to support biodiversity management, conservation efforts, and the identification of biodiversity knowledge gaps. Therefore, for users seeking more detailed taxonomic classifications, we recommend supplementing our data with information from other specialized databases or publicly available taxonomic resources, such as the World Register of Marine Species7, Plants of the World Online8 and others.

Degree of establishment & Conservation status

Degree of establishment

As defined by the Darwin Core framework9 , the "degreeOfEstablishment" refers to the extent to which an organism survives, reproduces, and expands its range in a given location and timeframe10 . It reflects how well a species is established in a particular environment, based on its ability to persist and spread. In Balearica, we used the terms outlined by the Darwin Core framework, along with some additional terms relevant to our focus.

We also identify who provides the information in the degree of establishment. This information can come from a taxonomic expert, scientific articles, or specific databases.

Degree of establishment

Categories of Degree of Establishment and their definitions:

  • Unknown: The establishment status of the organism is uncertain or unrecorded.
  • Doubtful: The organism is suspected to have minimal survival or reproductive success in the area.
  • Absent: The organism is not present in the location, or it has failed to establish.
  • Endemic: The organism is native and restricted to a specific geographic area.
  • Native: Not transported beyond limits of native range.
  • Captive: Individuals in captivity or quarantine (i.e. individuals provided with conditions suitable for them, but explicit measures of containment are in place).
  • Cultivated: Individuals in cultivation (i.e. individuals provided with conditions suitable for them, but explicit measures to prevent dispersal are limited at best).
  • Released: Individuals directly released into novel environment.
  • Failing: Individuals released outside of captivity or cultivation in a location, but incapable of surviving for a significant period.
  • Casual: Individuals surviving outside of captivity or cultivation in a location, no reproduction.
  • Reproducing: Individuals surviving outside of captivity or cultivation in a location, reproduction is occurring, but population not self-sustaining.
  • Established: Individuals surviving outside of captivity or cultivation in a location, reproduction occurring, and population self-sustaining.
  • Colonising: Self-sustaining population outside of captivity or cultivation, with individuals surviving a significant distance from the original point of introduction.
  • Invasive: Self-sustaining population outside of captivity or cultivation, with individuals surviving and reproducing a significant distance from the original point of introduction.
  • Widespread Invasive: Fully invasive species, with individuals dispersing, surviving and reproducing at multiple sites across a greater or lesser spectrum of habitats and extent of occurrence.


Conservation status

In Balearica, the IUCN Red List Assessment is provided. This information is provided exclusively at the species level. To date, there are three levels of "Scope of Assessment": Global, Europe, and Mediterranean. These levels indicate whether the assessment applies to the species' entire global population or just to a specific region of its range11.

For full details about the Red List categories, please visit IUCN Red List categories and criteria12.

Conservation status

IUCN Red List Categories:

  • Not Evaluated (NE): When a taxon has not yet been evaluated against the criteria.
  • Data Deficient (DD): When there is inadequate information to make a direct, or indirect, assessment of the risk of extinction based on taxon distribution and/or population status.
  • Least Concern (LC): When a taxon has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened.
  • Near Threatened (NT): When a taxon has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future.
  • Vulnerable (VU): When the best available evidence indicates that a taxon meets any of the criteria A to E for Vulnerable, and it is therefore considered to be facing a high risk of extinction in the wild.
  • Endangered (EN): When the best available evidence indicates that a taxon meets any of the criteria A to E for Endangered, and it is therefore considered to be facing a very high risk of extinction in the wild.
  • Critically Endangered (CR): When the best available evidence indicates that a taxon meets any of the criteria A to E for Critically Endangered, and it is therefore considered to be facing an extremely high risk of extinction in the wild.
  • Extinct in the Wild (EW): When a taxon is known only to survive in cultivation, in captivity or as a naturalized population/s well outside the past range.
  • Extinct (EX): When there is no reasonable doubt that the last individual of a taxon has died.
  • Conservation Dependent (CD): When a taxon is dependent on conservation efforts to prevent it from becoming endangered.
  • Not Applicable (NA): A taxa that occur in the region but have been excluded from the regional Red List for a specific reason.


Systems

Similar to the IUCN Red List, Balearica provides information on the "system" in which a taxon occurs. In this context, "system" refers to the broad ecological environment or habitat where a taxon primarily lives. We have chosen to use the same terminology as the IUCN Red List to ensure consistency.

Systems

Systems:

  • Terrestrial: Species that primarily inhabit land-based ecosystems (e.g., forests, grasslands, deserts).
  • Freshwater: Species that depend on freshwater habitats like rivers, lakes, and wetlands.
  • Marine: Species that inhabit saltwater environments, including oceans, coral reefs, and coastal areas.


Habitats

Balearica also provides information on the habitats in which a taxon occurs. To ensure consistency, the same terminology as the IUCN Red List has been used, following the IUCN Habitats Classification Scheme v3.1. The habitat information reflects the taxon's overall ecological preferences, so it may include habitats not formally found in the Balearic environment (i.e., Savanna, for the Eurasian hoopoe Upupa epops). We retrieved habitat information from the species and its lower taxonomic levels (i.e., subspecies and varieties); for higher taxonomic levels, habitats represent the sum of those lower levels.

Habitats

Habitats:

  • Forest: Areas dominated by trees, including tropical, temperate, and boreal forests.
  • Savanna: Grasslands with scattered trees, typically found in tropical and subtropical regions.
  • Shrubland: Areas covered by shrubs and small trees, often in dry or semi-arid climates.
  • Grassland: Open landscapes dominated by grasses, with few or no trees.
  • Wetlands (inland): Areas with standing or flowing freshwater, such as swamps, marshes, and bogs.
  • Rocky areas: Habitats with exposed rock, such as cliffs, mountains, and rocky outcrops.
  • Caves & subterranean habitats (non-aquatic): Underground environments, including dry caves and tunnels.
  • Desert: Dry, arid regions with sparse vegetation and extreme temperature variations.
  • Marine neritic: Shallow coastal waters, including coral reefs and continental shelves.
  • Marine oceanic: Open ocean beyond the continental shelf, with deep waters.
  • Marine deep ocean floor: The seafloor at great depths, including benthic and demersal zones.
  • Marine intertidal: Coastal areas exposed to air at low tide and submerged at high tide.
  • Marine coastal/supratidal: Coastal zones above the high tide line, such as salt marshes and dunes.
  • Artificial/terrestrial: Human-made environments, like urban areas, farmland, and plantations.
  • Artificial/aquatic: Human-created water bodies, such as reservoirs, canals, and ponds.
  • Introduced vegetation: Areas dominated by non-native plant species.
  • Other: Habitats that do not fit into the defined categories.
  • Unknown: Habitat not specified or not well-documented.


Directives

Balearica provides information on whether a species is protected under national and/or international laws.

Directives

International directives:

  • CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora): Regulates international trade of endangered species to ensure their survival (link).
  • Birds Directive: A European Union directive aimed at protecting wild bird species and their habitats(link).
  • Habitat Directive: A European Union directive focused on conserving natural habitats and wild species across member states (link).

National directives:

  • LESPRE (Listado de Especies Silvestres en Régimen de Protección Especial): Include endangered animals and plants in Spain (link).
  • CEEA (Catálogo Español de Especies Amenazadas): Lists animals and plants in Spain that are at risk of extinction (link).

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  2. GBIF.org. Gbif home page. 2025. Accessed: 2025-10-14. URL: https://www.gbif.org. ↩

  3. O. Bánki, Y. Roskov, M. Döring, G. Ower, D. R. Hernández Robles, C. A. Plata Corredor, T. Stjernegaard Jeppesen, A. Örn, T. Pape, D. Hobern, S. Garnett, H. Little, R. E. DeWalt, K. Ma, J. Miller, T. Orrell, R. Aalbu, J. Abbott, R. Adlard, and et al. Catalogue of life (version 2025-03-14). 2025. Accessed: 2025-10-14. URL: https://doi.org/10.48580/dgnz3. ↩↩

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  5. Dennis A. Benson, Mark Cavanaugh, Karen Clark, Ilene Karsch-Mizrachi, David J. Lipman, James Ostell, and Eric W. Sayers. Genbank. Nucleic Acids Research, 41(D1):D36–D42, 11 2012. doi:10.1093/nar/gks1195. ↩

  6. S. Ratnasingham, C. Wei, D. Chan, J. Agda, J. Agda, L. Ballesteros-Mejia, H. Ait Boutou, Z. M. El Bastami, E. Ma, R. Manjunath, D. Rea, C. Ho, A. Telfer, J. McKeown, M. Rahulan, C. Steinke, J. Dorsheimer, M. Milton, and P. D. N. Hebert. Bold v4: a centralized bioinformatics platform for dna-based biodiversity data. In DNA Barcoding: Methods and Protocols, chapter 26, pages 403–441. Springer US, New York, NY, 2024. ↩

  7. WoRMS Editorial Board. World register of marine species. 2025. Accessed: 2025-10-14, hosted at VLIZ. URL: https://www.marinespecies.org, doi:10.14284/170. ↩

  8. POWO. Plants of the world online. 2025. Accessed: 2025-10-14. URL: https://powo.science.kew.org/. ↩

  9. J. Wieczorek, D. Bloom, R. Guralnick, S. Blum, M. Döring, R. Giovanni, and D. Vieglais. Darwin core: an evolving community-developed biodiversity data standard. PLOS ONE, 7(1):e29715, 2012. doi:10.1371/journal.pone.0029715. ↩

  10. Darwin Core Maintenance Group. Degree of establishment controlled vocabulary list of terms. 2020. Accessed: 2025-10-14. URL: http://rs.tdwg.org/dwc/doc/doe/2020-10-13. ↩

  11. IUCN. The iucn red list of threatened species (version 2024-2). 2024. Accessed: 2025-03-20. URL: https://www.iucnredlist.org. ↩

  12. IUCN. IUCN Red List Categories and Criteria: Version 3.1, Second Edition. IUCN, Gland, Switzerland and Cambridge, UK, 2012. URL: https://www.iucnredlist.org. ↩