Bird population decline: Why conservation goals are missing the mark

Across Europe, conservation plans for birds often start their timelines in the 1970s. New analyses of bird population records from 1900 to 2018 for 170 European species show why that start date can be misleading,

Large bird population declines were already underway by mid-century, and the article reports a high risk of shifted baselines for 28 species and a probable high risk for seven more, roughly 40 percent of those assessed.

The term shifting baseline syndrome (SBS) was coined to explain how each generation accepts a degraded state as the new normal, then plans around it, a concept introduced by fisheries scientist Daniel Pauly in 1995. 

Historical trends in bird populations

The study was led by Elie Gaget of Tour du Valat and the University of Turku (UTU), who works on how long-term change alters bird populations.

His team reconstructed century-scale trends for waterbirds – species tied to lakes, rivers, marshes, and coasts – and for seabirds, species that spend most of their lives at sea.

The researchers leaned on historical texts, early notebooks, and standardized counts to track when trajectories bent.

Many of the species depend on wetlands, which are water-soaked habitats like marshes and swamps that store water, filter pollution, and buffer floods.

Decades of bird population decline

“Restoring bird populations to their 1970s levels is not enough: their decline began long before that,” said Thomas Galewski.

It is tempting to use those counts as the starting line, but modern monitoring exploded in the 1970s.

Setting goals that anchor to the 1970s risks locking in loss because the earlier fall is invisible in the dataset.

The team found varied histories before 1970, with some species rising, some falling, and many fluctuating, which means one date cannot stand in for a century of change.

Some species are long-term losers

The researchers pieced together patterns from historical accounts, early ornithological works, and standardized counts, then mapped where trend shifts occurred across 1900 to 2018.

Many declines began decades before standardized monitoring, so short timelines miss the point where restoration must begin.

They also graded risk categories to flag where modern targets are most likely to under shoot. Species tagged as high or probably high risk need baselines that predate large habitat shifts.

For several species, the decline never stopped. The Black Tern and the Corncrake are singled out as long-term losers, and “These species should be placed as a priority for conservation efforts,” said Gaget.

Threats that drive bird declines

Europe has a legal framework to protect wild birds and their breeding and resting sites.

The directive sets conservation duties for every member state, but rules only work when targets line up with history rather than convenience. Threats that drove early declines still cut deep today.

Habitat loss, caused by draining or fragmenting wetlands, intensive agriculture, pollution, overfishing, and illegal or unsustainable hunting, continues to pressure populations, and climate change stacks stress on top.

Some species have rebounded

Success stories matter, yet they can hide the scale of earlier loss if you forget where populations began.

Greater Flamingos almost vanished from Western Europe before protections and site management helped the species recolonize the Mediterranean, and long-term studies from the Camargue explain how colony management and ringing supported recovery.

Great Cormorants have also rebounded in many coastal and inland waters after decades of persecution eased.

That rise is real, but recovery to common status in some places is not the same as a return to early 20th-century abundance across the range.

Defining a credible baseline

A credible baseline should be old enough to capture pre-monitoring declines and detailed enough to guide action.

The century scale that underpins the new analysis does both, and it aligns with how ecologists think about historical reference states and with the aim of reversing long-standing erosion of biodiversity. Policy can absorb that shift without getting stuck in the past.

Targets can use flexible reference periods that reach back where data exist, then translate those ambitions into near-term steps that budgets and agencies can deliver now.

Long-term monitoring and conservation

“Long-term monitoring, such as censuses, is our best weapon against the shifting baseline syndrome,” said Galewski.

That monitoring keeps memory alive by creating public records that cannot be shrugged off when leadership changes. Citizens, researchers, and local land managers have roles in that memory work.

National programs, cross-border counts, and open data make it possible to see broad patterns rather than isolated anecdotes, which helps separate noise from trend.

Restoration plans for bird recovery

If at least 40 percent of assessed species face a risk of mismatched baselines, then many restoration plans will underestimate the lift needed. That blind spot can turn a celebrated target into a ceiling that leaves bird populations trapped below their historical levels.

A better plan starts by asking where the trajectory turned down. Rebuilding then focuses on the places and seasons where mortality and failure stack up, whether that is nesting grounds in farmed lowlands, bycatch risk at sea, or winter food scarcity in estuaries.

The study is published in Biodiversity and Conservation.

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