Raso Lark
Encyclopedia
The Raso Lark is a small passerine
bird with a highly restricted range, being found only on Raso islet in the Cape Verde Islands. This critically endangered
member of the Alaudidae lives in highly 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.
; all three of these islands were joined in the last Ice Age
. Branco island itself has no permanent water and has never been inhabited by people, a fact that has probably saved the lark from extinction until now.
The Raso Lark feeds by digging in the ground for insect
larva
e, and bulb
s of the nutsedge. Both sexes also feed on grass seeds, and insects such as butterflies, moths and grasshopper
s. It has an enlarged bill, but it is not used for foraging, but for dominance displays among males.
The female lays one to three eggs after the rains. Courtship behaviour is like that of the Skylark
. The incubation time is thought to be 15 days.
Cape Verde giant gecko. The Neglected Common Kestrel
Falco tinnunculus neglectus is a predator of Razo larks. Although the island is currently free of mammalian predators such as rat
s or feral cat
s, and is a closed reserve, the likelihood of a single unauthorized visit causing massive damage remains high. It has been suggested that establishing a second population on the gecko-free island of Santa Luzia, which historically might also have had the lark, should be a conservation
priority.
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
bird with a highly restricted range, being found only on Raso islet in the Cape Verde Islands. This critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
member of the Alaudidae lives in highly 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
Ornithology
Ornithology is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds...
study on the archipelago as a whole.
Description
The Raso Lark is restricted to one small island in the Cape Verde group, although historically it is believed to have ranged over two other islands, Branco and São Vicente IslandSão Vicente Island
São Vicente Island may refer to:* São Vicente, Cape Verde* São Vicente Island...
; all three of these islands were joined in the last Ice Age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
. Branco island itself has no permanent water and has never been inhabited by people, a fact that has probably saved the lark from extinction until now.
The Raso Lark feeds by digging in the ground for insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, and bulb
Bulb
A bulb is a short stem with fleshy leaves or leaf bases. The leaves often function as food storage organs during dormancy.A bulb's leaf bases, known as scales, generally do not support leaves, but contain food reserves to enable the plant to survive adverse conditions. At the center of the bulb is...
s of the nutsedge. Both sexes also feed on grass seeds, and insects such as butterflies, moths and grasshopper
Grasshopper
The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper...
s. It has an enlarged bill, but it is not used for foraging, but for dominance displays among males.
The female lays one to three eggs after the rains. Courtship behaviour is like that of the Skylark
Skylark
The Skylark is a small passerine bird species. This lark breeds across most of Europe and Asia and in the mountains of north Africa. It is mainly resident in the west of its range, but eastern populations are more migratory, moving further south in winter. Even in the milder west of its range,...
. The incubation time is thought to be 15 days.
Threats
The tiny population size, last thought to be ~150 birds, coupled with the highly skewed sex ratio (around 2 males to each female) make this species one of real concern. The reproductive success of the birds is very low, probably due to predation by the near-endemicEndemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
Cape Verde giant gecko. The Neglected Common Kestrel
Common Kestrel
The Common Kestrel is a bird of prey species belonging to the kestrel group of the falcon family Falconidae. It is also known as the European Kestrel, Eurasian Kestrel, or Old World Kestrel. In Britain, where no other brown falcon occurs, it is generally just called "the kestrel".This species...
Falco tinnunculus neglectus is a predator of Razo larks. Although the island is currently free of mammalian predators such as rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
s or feral cat
Feral cat
A feral cat is a descendant of a domesticated cat that has returned to the wild. It is distinguished from a stray cat, which is a pet cat that has been lost or abandoned, while feral cats are born in the wild; the offspring of a stray cat can be considered feral if born in the wild.In many parts of...
s, and is a closed reserve, the likelihood of a single unauthorized visit causing massive damage remains high. It has been suggested that establishing a second population on the gecko-free island of Santa Luzia, which historically might also have had the lark, should be a conservation
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
priority.