Start with the species’ IUCN Red List assessment for a current status and any reported population trend or estimate. For actual population time series, search the Living Planet Database for monitored vertebrate populations, or use GBIF survey datasets to examine recorded presence, absence, or abundance. None is a complete census of all wildlife: check each result’s species, geography, years, measure, method, and uncertainty before drawing conclusions.
Choose a source that matches your question
Species assessments, monitoring records, survey observations, and global indicators answer different questions. There is no single comprehensive source of comparable population counts for every species and region.
IUCN Red List: species status and assessment details
Search the IUCN Red List for the species’ assessment. Depending on the taxon and available evidence, it may report a population trend, describe population structure, or give an estimate of mature individuals. A numeric count is not available for every species, and assessors may rely on indirect information. Check whether the assessment is global or regional and when it was made: a regional assessment does not describe the entire species range. IUCN’s supporting information can provide assessment citations, downloadable assessment material, and spatial data.
Living Planet Database: monitored vertebrate time series
Search the Living Planet Database when you need time-series evidence about monitored vertebrate populations. Its records draw on sources such as scientific journals, online databases, and government reports, and the portal supports searching and downloading. These are monitored records, not a census of all vertebrates or a complete estimate of every population.
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GBIF: survey records across places and times
Use GBIF biological survey datasets when you need records of species presence, absence, or abundance across locations and dates. Systematically collected survey data can be useful for comparisons, but recorded observations depend on survey design, effort, and coverage. A count of records is not a complete population estimate.
Red List Index: change in extinction risk
The Red List Index (RLI) tracks change in extinction risk across assessed species. It is not a measure of population abundance and should not be used as a species population count.
How to check whether a result applies to the species
- Match the taxon. Check the scientific name and synonyms, including any taxonomic changes. A common name can refer to a different species or population; IUCN assessment pages list scientific names and synonyms.
- Check geography and boundaries. Establish whether the result is global, regional, or limited to a monitored site or population. Do not apply a local result to an entire species range without evidence.
- Read the dates. Record the assessment or publication date and the years covered by the underlying observations. A recently updated page may still summarize older field data.
- Identify exactly what was measured. Mature individuals, density, abundance per sample, a population index, and a proxy such as nest counts are different quantities. Do not compare them as equivalent counts.
- Inspect coverage and uncertainty. For a time series, note its length, missing years, monitoring sites, sampling method, and whether it represents one population or a wider area. The Living Planet Index documentation notes that underlying series vary in length and completeness, with shorter series for some groups.
- Keep population trend separate from extinction risk. “Decreasing” describes a population trend; threatened-category assessments and the RLI concern extinction risk under assessment criteria. One cannot be mechanically substituted for the other.
- Treat missing information as missing. “Unknown,” “Data Deficient,” or the absence of an estimate does not show that a population is stable or absent. Look for cited assessments, monitoring reports, or original studies, and state their limits.
How to compare two population claims
Before comparing figures, align the taxon and taxonomy, geographic area and population boundary, years covered, publication or assessment dates, measure, method, sampling effort, completeness, and uncertainty. Also establish whether each result is a direct estimate, a proxy, or an aggregate indicator. If those attributes differ, the numbers may describe different things rather than a real change.
What the global Living Planet Index figure means
The Zoological Society of London and WWF reported a 73% average decline in monitored wild vertebrate populations between 1970 and 2020 in the 2024 Living Planet Index. The LPI describes itself as measuring “the average change in the size of wild populations of vertebrate species over time.” The 73% figure is an average population-abundance trend; it does not mean that 73% of species declined or that 73% of animals disappeared. Nor did every monitored population decrease: the LPI explains that approximately half of populations in the global index show stable or increasing trends and half declining trends. The average reflects the size and weighting of those trends. Read the Living Planet Index explanation for its scope and interpretation.
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A practical way to report what you find
When sharing a result, name the source and species, state the geographic scope and years, identify the measure, and describe the main limitation. For example, say “the assessment reports a decreasing trend for this region” rather than presenting it as a global count if the source is regional. If a number is an index or proxy, label it as such; if the source provides no numeric estimate, do not infer one from the trend category.
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