Raso lark

This critically endangered member of the family Alaudidae lives in very arid terrain, and is considered one of the least known birds in the Western Palaearctic region, due to its remoteness and the lack of much ornithological study on the archipelago as a whole.

The Raso lark is considered an adult when it has developed a reddish-brown tone between the ears and tail, with a pattern on the crown and back.

Evidence from subfossil bone deposits reveal that the Raso lark once also existed on the islands of Santa Luzia, São Vicente, Santo Antão, and possibly Branco during the glacial times, before human colonization in the 15th century.

Most Raso larks are found on level plains with volcanic soil and are associated with small vegetated patches along dry stream beds in which it feeds and breeds.

Their most common areas of habitation are near dry river beds, but due to the scarcity of water, only patches of vegetation remain for Raso larks to reside in.

The Raso lark's sensitivity to drought has kept it endangered for several years due to the dry climate on the Cape Verde islands.

[3] Flocks have also been observed feeding among rocks close to the sea, and the birds excavate holes in sandy soil to extract the small bulbs of nutsedges, which are perennial weeds in the sedge family that superficially resemble grasses.

The females, even though smaller in size, still provide by gathering bulbs while the males stay in the burrows and vigorously watch over the nest, protecting it from outside intruders.

Additionally, Raso larks are vulnerable to the threat of accidental introduction of cats, dogs, rats by fishermen or other visitors to the island.

Within the habitat of the Raso lark, the Cape Verde giant geckos weigh roughly 100 g and include juvenile birds in their diet.

The tiny population size, which fluctuates from ~200-1,000 birds, coupled with the highly skewed sex ratio (around two males to each female) make this species critically endangered.

Although the island is currently free of mammalian predators such as rats or feral cats, and is a closed reserve, the likelihood of a single accidental introduction causing catastrophic damage remains high.