Meet the Raso lark: The critically endangered songbird of Cape Verde

One Earth’s “Species of the Week” series highlights an iconic species that represents the unique biogeography of each of the 185 bioregions of the Earth.

On a remote speck of volcanic rock in the Atlantic Ocean, where the wind carves stories into the cliffs and salt-spray nourishes life, a bird sings a song almost no one hears. This is the Raso lark (Alauda razae), a species so rare that its entire global population could once fit in a school gymnasium. Found only on the tiny, uninhabited Raso Islet in Cape Verde, the Raso lark is one of the most endangered birds on Earth.

Yet, within this fragile bird lies a powerful story of survival, adaptation, and the delicate balance of ecosystems teetering on the edge. The Raso lark matters, not only because of its rarity, but because it represents the resilience of island species and the urgency of conservation in a warming world.

Habitat and environment

Raso Islet, just seven square kilometers in size, is a windswept and arid land off the coast of West Africa. With no permanent freshwater sources, sparse vegetation, and no human inhabitants, the environment may seem inhospitable. But it is precisely this isolation that has protected the Raso lark from the threats that decimated many other island species.

Here, the lark nests in rocky crevices and feeds among low grasses and shrubs. It has adapted to the island’s drought-prone climate by reducing its energy needs and taking advantage of seasonal insect blooms. However, the islet’s harshness also makes life precarious, during prolonged droughts, food scarcity can lead to population crashes.

Raso’s isolation is both a sanctuary and a trap. The introduction of predators like cats or rats, which have wiped out birds on nearby islands, would be catastrophic. So would the arrival of diseases or rising seas that shrink the island’s already limited range.

Physical traits and behavior

The Raso lark is a medium-sized, ground-dwelling songbird, mottled brown and buff with subtle streaks that blend into the volcanic soil. Its most remarkable trait, however, lies in its legs, males have disproportionately long tarsi (lower legs), which they use in elaborate courtship displays, strutting and bounding to impress females.

The species is sexually dimorphic: males are larger and more vocal, while females tend to be smaller and more cryptically colored. Raso larks feed primarily on seeds and insects, foraging carefully across the rocky landscape, especially after rainfall when food becomes more abundant.

Their breeding season is opportunistic, triggered by rainfall. After heavy rains, the islet becomes briefly lush, and larks begin nesting in shallow scrapes on the ground. However, if rains fail, they may not breed at all, leading to years without any chicks being born. Each clutch contains two to three eggs, but predation and heat exposure can lower the survival rate significantly.

Ecological role

Though it inhabits a tiny, seemingly barren island, the Raso lark plays a key role in its ecosystem. As an insectivore and seed disperser, it contributes to controlling insect populations and cycling nutrients across the island’s sparse flora.

Its presence also serves as a bioindicator: a sudden drop in population reflects shifts in climate patterns, rainfall, and insect abundance. Scientists studying the Raso lark gain valuable insights into how climate change affects isolated island ecosystems and how to manage them.

The bird’s restricted range makes it especially vulnerable to ecological imbalance. If the Raso lark were to disappear, it would create a vacuum in the island’s already limited biodiversity, impacting everything from insect populations to seed regeneration.

Cultural and mythological significance

While the Raso lark doesn’t have a deep well of folklore like other iconic species, its symbolic value lies in its rarity. For the people of Cape Verde and the global conservation community, it has become a quiet emblem of the unique natural heritage found in the archipelago.

The lark is a reminder of how evolution can craft extraordinary life forms in isolation, and how quickly those forms can vanish when the world changes too fast. In its solitude, it speaks to our human yearning to protect what is rare, irreplaceable, and beautiful.

Conservation status and challenges

The Raso lark is classified as Critically Endangered by the IUCN Red List, with an estimated population fluctuating between 1,000 and 1,600 individuals, depending on rainfall. 

Key threats include:

• Climate change, especially prolonged droughts that reduce breeding success.
• Invasive species, particularly if rats or cats are accidentally introduced.
• Sea level rise, which could shrink or inundate the islet.
• Genetic bottleneck, with such a small population making inbreeding a growing concern.

But there is hope. In recent years, conservationists have launched a bold project to establish a second population on the nearby island of Santa Luzia. Carefully raised and translocated individuals are now breeding there, providing a critical “insurance policy” against extinction.

The Cape Verde government, in partnership with international NGOs, has also designated protected status for Raso and its surrounding islets, limiting access and monitoring the ecosystem closely.

The future echoes in its song

The Raso lark’s song may be carried only by the Atlantic winds, unheard by most of the world, but it is a call worth listening to. In its delicate balance between survival and extinction, the Raso lark shows us what’s at stake when nature is left teetering at the edge.

This tiny bird on a forgotten island tells a larger story: that even the most fragile lives deserve a chance, that the threads of biodiversity are interconnected, and that our actions, however distant, can preserve or destroy the beauty of our planet.

You can make a difference. Support conservation programs working to protect island species. Advocate for climate action. And spread the story of the Raso lark, so its voice never goes silent.

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