Justification This species is confined to one very small island, where its population fluctuates in response to rainfall and appears to reach extremely small numbers. Climate change may increase drought in Cape Verde, adding to the likelihood of extinction. As a ground-nester, the species is highly at risk from the accidental introduction of predators. For all of these reasons, it is classified as Critically Endangered.

Family/Sub-family Alaudidae

Species name author (Alexander, 1898)

Taxonomic source(s) AERC TAC (2003), Cramp and Simmons (1977-1994), Dowsett and Forbes-Watson (1993), Sibley and Monroe (1990, 1993)

Identification 18 cm. Small, heavy-billed lark. Thick-based heavy bill, particularly in males, imparts an upturned appearance. Body plumage heavily streaked with buff and black, short erectile crest. Heavily streaked on breast, paler underparts. Voice Described as similar to Common Skylark A. arvensis, given both from the ground and in display-flight.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

150

fluctuating

2 km²

Yes

Range & population Alauda razae is restricted to the very small (7 km²), arid, uninhabited island of Raso in the Cape Verde Islands, although previously it may have occurred on Branco, Santa Luzia and Sao Vicente which formed a single island during the last glacial low 18,000 years BP. Suitable breeding habitat covers less than half the area of Raso. The lark's population is believed to fluctuate in response to climate and continues to do so. From the mid 1960s to the early 1980s, the population was estimated at only 20-50 pairs⁵. In early 1985, however, a survey showed at least 150 birds to be present. Subsequent day visits resulted in the following estimates: 75-100 pairs in early 1986 and early 1988, c.250 birds in late 1988, c.200 birds in early 1989, c.250 birds in early 1990 and 1992. Complete censuses of the island in 1998 and 2003 found 92 and 98 birds respectively, restricted to the south and west of the islet^5,7, but following rain in 2004 the population rapidly increased to 130 individuals in 2005⁸ and 150 in November 2007⁹. Only a third of these are female^7,8. Whether this is a real decline or a pattern in the naturally fluctuating population is unclear⁷.The present population size is approximately the same as that believed to exist in the 1960s⁵.

Important Bird Areas Click here to view map showing IBAs where species is recorded and triggers any of the IBA criteria.

Ecology: It is found on level plains with volcanic soil and is associated with small vegetated patches along dry stream beds in which it feeds and breeds⁵. There is significant difference in bill size between males and females enabling the species to exploit limited food resources, with both sexes having relatively larger bills than congeners^6,8. A number of desert-dwelling larks have evolved long bills, apparently to aid digging for food in a sandy environment⁸. Flocks have also been observed feeding among rocks close to the sea, and the birds (particularly males) excavate holes in sandy soil to extract the small bulbs of nutsedges Cyperus bulbosus or C. cadamosti⁸. Breeding is erratic and governed by the slight and irregular rains^2,6. The population changes rapidly in response to rain; a prerequisite for breeding,^5,6,8 and has fallen to extremely low levels during droughts^5,6,8. At present c.70% (68/98) of the population is male⁷. During the non-breeding season birds aggregate into flocks⁸ and can be found in other parts of the island. Adult survival appears to be high and the species is thought to be relatively long-lived⁸. Breeding success is very low, due to high predation by the near-endemic gecko Tarentola gigas.

Threats Drought over successive breeding seasons is undoubtedly the cause of the extremely small current population. Given its sensitivity to drought, long-term desertification in the Cape Verdes is clearly a major threat⁵. In addition, nest predation (probably by a near-endemic gecko) is high⁶. Ground-nesting makes it extremely vulnerable to the potential accidental introduction of rats, cats and dogs brought to the island by fishers visiting the islet to collect seabirds' eggs and young⁴. The danger of such introductions (and the potential impact of non-native plant introductions) is now exacerbated by increased tourist activity in the Cape Verde islands. Evidence of cats^5,6 and dogs⁶ on the island was found during surveys in 1998 and 2001 but these populations did not appear to establish themselves and the island is currently considered to be mammal-free. Global climate change is likely to threaten this small and precipitation-dependent species.

Conservation measures underway Raso Lark has been officially protected under Cape Verde law since 1955⁶ and in 1990, Raso was declared a national park². To date there has been no enforcement of these laws on the ground³. Surveys have revealed the absence of cats on the island. Annual population monitoring has been carried out since 2001, and future research is planned to understand the conditions needed to enable successful breeding⁹. The practicalities and desirability of a possible translocation project are being investigated⁹.

Conservation measures proposed Conduct research into other potential nest predators. Investigate the suitability of Santa Luzia as a potential location for the establishment of a second population by conducting appropriate ecological research⁶. Investigate reasons for the male biased sex ratio⁶. Raise awareness amongst tourists and tour operators visiting Raso to ensure precautions are taken to avoid the accidental introduction of alien species and safeguard the fragile island ecology. Maintain good relations with fishers using the island and engage them in conservation activities. Continue regular monitoring of the population and the status of introduced predators. Prevent the establishment of non-native mammalian predators and plants on Raso.

References Collar and Stuart (1985). 1. Castell (1999). 2. Hazevoet (1995). 3. Hazevoet (1999a). 4. C. J. Hazevoet in litt. (1995). 5. Ratcliffe et al. (1999). 6. Donald et al. (2003). 7. P. Donald in litt. (2003). 8. Donald and Brooke (2006). 9. M. Brooke in litt. (2008).

Further web sources of information

Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

Species Guardian Action Update November 2008

Text account compilers Phil Benstead (BirdLife International), Jeremy Bird (BirdLife International), Jonathan Ekstrom (BirdLife International), Sue Shutes (BirdLife International), Andy Symes (BirdLife International)

Contributors Michael Brooke (University of Cambridge), Paul Donald (Royal Society for the Protection of Birds), Cornelis Hazevoet (Universidade de Lisboa)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Andy Symes (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Alauda razae. Downloaded from http://www.birdlife.org on 9/2/2010

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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