The Extinction of the Slender-billed Curlew and the Global Conservation Crisis of Shorebirds

 

                                             Slender-billed Curlew declared extinct 

 Curlews, Slender-billed Curlew / By Mary Colwell

*Heri tarmizi

Abstract

The extinction of the Slender-billed Curlew represents a significant warning signal for global shorebird conservation. Once a migratory species breeding in western Siberia and wintering around the Mediterranean region, the species was last reliably observed in Morocco in 1995 and was formally declared extinct in 2024 after decades without confirmed sightings. This paper reviews the historical records, ecological characteristics, and causes of extinction of the Slender-billed Curlew and analyzes broader trends in shorebird conservation using International Union for Conservation of Nature (IUCN) Red List data. The decline of shorebird populations worldwide is linked to habitat loss, climate change, hunting, and degradation of migratory stopover sites. The extinction of this species highlights the urgency for stronger conservation strategies across migratory flyways.

1. Introduction

Shorebirds (order Charadriiformes) represent one of the most threatened groups of migratory birds globally. Many species rely on interconnected habitats across continents, including breeding grounds, migratory stopover sites, and wintering areas. Human activities have severely impacted these ecosystems, leading to population declines and increased extinction risk.

One of the most striking examples of this crisis is the disappearance of the Slender-billed Curlew, a migratory wader once distributed across Eurasia and North Africa. This species’ extinction demonstrates how cumulative pressures on migratory birds can result in irreversible biodiversity loss.

2. Literature Review

2.1 Historical distribution and ecology

The Slender-billed Curlew (Numenius tenuirostris) was a medium-sized migratory shorebird belonging to the family Scolopacidae. The species likely bred in steppe and wetland habitats in western Siberia and the Kazakh steppe and migrated to wintering grounds around the Mediterranean Basin, North Africa, and the Middle East.

The bird measured approximately 36–41 cm in length and fed mainly on invertebrates such as insects, worms, and crustaceans found in wetlands and coastal habitats.

Despite historical records suggesting it was locally common, sightings declined rapidly during the twentieth century.

2.2 Decline and last confirmed record

The last confirmed observation of the Slender-billed Curlew occurred in Morocco in February 1995. Subsequent reports across Europe and the Mediterranean region were considered unverified or misidentifications.

After nearly three decades without confirmed sightings and extensive search efforts across its possible range, scientists concluded that the species was almost certainly extinct. A 2024 population-modeling study estimated a 96% probability of extinction.

In 2024–2025, conservation organizations and the IUCN formally recognized the species as extinct.

3. Causes of Extinction

Several factors likely contributed to the extinction of the Slender-billed Curlew:

3.1 Habitat loss

Wetland drainage and agricultural expansion reduced suitable breeding and feeding habitats across Eurasia. Large areas of steppe and wetland ecosystems were converted to farmland during the twentieth century.

3.2 Hunting pressure

Historical records suggest hunting along migration routes contributed to population declines, especially during the early and mid-twentieth century.

3.3 Lack of ecological knowledge

Scientists had limited information about the species’ breeding sites and ecology, which hindered effective conservation planning.

3.4 Climate change and ecosystem degradation

Changing climate conditions, wetland degradation, and disturbance of coastal ecosystems may have further reduced habitat quality across the species’ migratory range.

4. Shorebird Conservation Status (IUCN Red List)

The extinction of the Slender-billed Curlew reflects broader patterns in global shorebird conservation. According to IUCN assessments:

• Many shorebirds are currently classified as Near Threatened, Vulnerable, Endangered, or Critically Endangered.

• Population declines are particularly severe in migratory species that depend on multiple international habitats.

Examples of threatened shorebirds include:

Species	IUCN Status
Far Eastern Curlew	Endangered
Spoon-billed Sandpiper	Critically Endangered
Great Knot	Endangered
Eurasian Curlew	Near Threatened

Declines in these species are linked to coastal development, habitat reclamation, pollution, and climate change.

5. Global Threats to Shorebirds

5.1 Habitat destruction

Loss of wetlands, tidal flats, and marshes is the primary threat to shorebirds worldwide.

5.2 Climate change

Rising sea levels and altered temperature patterns affect breeding grounds in Arctic and sub-Arctic regions.

5.3 Coastal development

Urbanization and aquaculture expansion destroy feeding areas along migration routes.

5.4 Disturbance and pollution

Human disturbance, oil pollution, and plastic contamination further degrade shorebird habitats.

6. Implications for Conservation

The extinction of the Slender-billed Curlew highlights several important lessons:

1. Migratory species require international conservation cooperation.

2. Early detection of population declines is essential.

3. Protecting migratory flyways and wetlands is critical for shorebird survival.

4. Climate change mitigation must be integrated into biodiversity conservation.

7. Conclusion

The extinction of the Slender-billed Curlew represents a significant loss for global biodiversity and serves as a warning for the future of migratory shorebirds. The combination of habitat loss, hunting, ecological uncertainty, and environmental change drove this species to extinction after its last confirmed sighting in 1995. Current trends in shorebird populations indicate that many other species face similar threats. Strengthening global conservation policies, protecting wetland ecosystems, and improving international collaboration are essential steps to prevent further losses.

References

BirdLife International (2024). Extinction assessment of Numenius tenuirostris.
IUCN Red List of Threatened Species.
Hilton et al. (2024). Population modelling and extinction probability of the Slender-billed Curlew.
Natural History Museum (2024). Slender-billed Curlew extinction analysis.
Britannica (2025). Slender-billed Curlew species profile.
BirdLife International news release.