Wildlife populations around the world have declined by an average of 73% since 1970, according to the 2026 Living Planet Index. Yet scientists warn that this alarming figure reveals only part of the story.

The assessment, produced by the World Wide Fund for Nature (WWF), is one of the most important tools for monitoring global biodiversity. However, researchers say that countless animal populations remain unrecorded, making it difficult to determine the true scale of wildlife loss.

Understanding these gaps could be essential for protecting endangered species and measuring the success of conservation efforts.

What Does The Decline Really Mean?

The reported 73% decline does not mean that nearly three-quarters of all wild animals have disappeared. Instead, it represents the average change in the size of monitored wildlife populations over time.

Some populations have increased, while others have experienced substantial reductions. Scientists use these observations to identify broader trends in biodiversity. However, the accuracy of such assessments depends on which species and locations are included.

Because monitoring programmes are unevenly distributed, the available information may not represent wildlife worldwide.

Why So Many Animals Go Uncounted

Unlike climate monitoring, which benefits from extensive weather stations and satellite measurements, tracking wildlife requires considerable fieldwork. Researchers must identify species, estimate their numbers and repeat observations over many years. Remote forests, wetlands and difficult terrain make these activities expensive and time-consuming.

Consequently, scientific records are concentrated in locations where researchers can work relatively easily. Many populations living outside established monitoring areas remain poorly understood. Historical information presents another challenge. Scientists cannot recreate reliable population counts from decades when no observations were recorded.

Protected Areas May Distort The Picture

Researchers Hannah Sarah Wauchope, Gary David Powney and Nick Isaac have highlighted another important limitation. Wildlife monitoring often concentrates on national parks and relatively undisturbed habitats. These locations may provide better conditions for animals than agricultural landscapes or expanding urban areas. As a result, existing records could underestimate biodiversity losses occurring outside protected areas. However, the opposite possibility also exists.

Threatened species and animals harvested by humans, including commercially exploited fish, may receive disproportionately close attention. Because these populations can experience substantial declines, their inclusion could influence overall estimates in the opposite direction. Scientists are still investigating how these different biases affect global assessments.

Why Some Populations Are Increasing

Not every environmental change causes all wildlife populations to decline. Certain species benefit when forests are converted into farmland, particularly birds adapted to agricultural habitats. However, habitat destruction often harms many more species than it benefits.

Replacing tropical forests with plantations or natural grasslands with buildings can eliminate habitats needed by specialised animals.

This variation makes biodiversity difficult to summarise using a single global percentage.

How Scientists Are Improving Wildlife Data

The Living Planet Index already gives greater weight to information from underrepresented regions, including Africa and South America.

Researchers are also developing statistical methods to identify and reduce sampling biases.

These improvements may help future assessments better reflect conditions across different ecosystems.

Nevertheless, limited historical records and incomplete monitoring remain serious obstacles.

Why Accurate Monitoring Matters

Reliable wildlife information helps conservation organisations identify vulnerable populations, evaluate habitat protection and direct resources towards areas of greatest need.

The findings also influence international efforts to meet biodiversity targets established through the United Nations.

Without representative data, important declines may remain undetected until populations become dangerously small.

The latest assessment highlights a difficult reality: protecting global wildlife requires understanding the animals already being monitored while finding better ways to study those scientists have barely begun to count.