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Raso Lark Alauda razae
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BirdLife Species Guardian Michael Brooke (University of Cambridge) & Paul Donald (RSPB)
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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.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: #http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls#.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.

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.

Distribution and population
Alauda razae is restricted to the very small (7 km2), arid, uninhabited island of Raso in the Cape Verde Islands, although evidence from sub-fossil bone deposits suggests that the species also occurred on Santa Luzia, São Vicente and Santo Antão prior to human colonisation in the 15th century, after which extinction on these islands appears to have been rapid (Mateo et al. 2009). It is likely that the species also occurred on Branco, which formed a single island with São Vicente, Santa Luzia and Raso 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 pairs (Ratcliffe et al. 1999). 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 (Ratcliffe et al. 1999, P. Donald in litt. 2003), but following rain in 2004 the population rapidly increased to 130 individuals in 2005 (Donald and Brooke 2006), 190 in November 2009 (M. Brooke in litt. 2008, 2010), and 1,490 in November 2011 (Brooke et al. 2012). When the population is low only a third of birds are female (P. Donald in litt. 2003, Donald and Brooke 2006). A single bird near Ponta do Barril on the island of São Nicolau in March 2009 is the only record away from Raso (Hazevoet 2012); it most likely represents a wandering bird from Raso.


Population justification
The population was estimated at 1,490 individuals in November 2011 (Brooke et al. 2012), which equates roughly to 990 mature individuals. However, when the population is lower it can be strongly male-biased, meaning the effective population size is smaller than it first appears (M. Brooke in litt. 2008, 2010, Brooke et al. 2010), and the population is therefore placed in the band 250-999 mature individuals.

Trend justification
The population undergoes fluctuations due to rainfall levels on Raso (Donald et al. 2003; Donald and Brooke 2006, Brooke et al. 2012). It has increased rapidly since 2004 but it is uncertain whether this relates to a temporary fluctuation or a longer-term increase.


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 breeds (Ratcliffe et al. 1999). 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 (Donald et al. 2003, Donald and Brooke 2006). A number of desert-dwelling larks have evolved long bills, apparently to aid digging for food in a sandy environment (Donald and Brooke 2006). 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. cadamosti (Donald and Brooke 2006). Breeding is erratic and governed by the slight and irregular rains (Hazevoet 1995, Donald et al. 2003). The population changes rapidly in response to rain; a prerequisite for breeding, and has fallen to extremely low levels during droughts (Ratcliffe et al. 1999, Donald et al. 2003, Donald and Brooke 2006). At times the population has been strongly male-biased (P. Donald in litt. 2003, M. Brooke in litt. 2008, 2010, 2012). During the non-breeding season birds aggregate into flocks (Donald and Brooke 2006) 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-lived (Brooke et al. 2012). Breeding success is sometimes very low, due to high predation by the near-endemic gecko Tarentola gigas. The single record from São Nicolau in March 2009 (Hazevoet 2012) perhaps indicates that the species has some limited dispersal capability.


Threats
Drought over successive breeding seasons reduces the population. Given the species's sensitivity to drought, long-term desertification in the Cape Verdes is clearly a major threat (Ratcliffe et al. 1999). In addition, nest predation (probably by a near-endemic gecko) is high in some years (Donald et al. 2003). Ground-nesting makes it extremely vulnerable to the potential accidental introduction of rats, cats and dogs brought to the island by fishers (C. J. Hazevoet in litt. 1995). 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 (Ratcliffe et al. 1999, Donald et al. 2003) and dogs (Donald et al. 2003) 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 mammal-free. Global climate change is likely to threaten this highly-restricted and precipitation-dependent species.

Conservation Actions Underway
Raso Lark has been officially protected under Cape Verde law since 1955 (Donald et al. 2003), and in 1990 Raso was declared a national park (Hazevoet 1995). To date there has been limited enforcement of these laws on the ground (Hazevoet 1999a). Surveys have revealed the absence of cats on the island. Collecting of young and eggs has now been halted by the activity of a local NGO, Biosfera (M. Brooke in litt. 2008, 2010). Annual population monitoring has been carried out since 2001, and future research is planned to understand the conditions needed to enable successful breeding (M. Brooke in litt. 2008, 2010). The practicalities and desirability of a possible translocation project are being investigated (M. Brooke in litt. 2008, 2010). Conservation Actions 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 research (Donald et al. 2003). 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
Brooke, M. de L.; Flower, T. P.; Campbell, E. M.; Mainwaring, M. C.; Davies, S.; Welbergen, J. A. 2012. Rainfall-related population growth and adult sex ratio change in the Critically Endangered Raso lark (Alauda razae). Animal Conservation DOI: 10.1111/j.1469-1795.2012.00535.x.

Brooke, M. de L.; Flower, T. P.; Mainwaring, M. C. 2010. A scarcity of females may constraint population growth of threatened bird species: case notes from the Critically Endangered Raso Lark Alauda razae. Bird Conservation International 20(4): 382-384.

Castell, P. 1999. Notes on the breeding biology of Raso Lark Alauda razae. Bulletin of the African Bird Club 6(2): 103-106.

Collar, N. J.; Stuart, S. N. 1985. Threatened birds of Africa and related islands: the ICBP/IUCN Red Data Book. International Council for Bird Preservation, and International Union for Conservation of Nature and Natural Resources, Cambridge, U.K.

Donald, P. F.; Brooke, M.deL. 2006. An unlikely survivor: the peculiar natural history of the Raso Lark. British Birds 99: 420-430.

Donald, R. F.; de Ponte, M.; Groz, M. J. P.; Taylor, R. 2003. Status, ecology, behaviour and conservation of Raso Lark Alauda razae. Bird Conservation International 13: 13-28.

Hazevoet, C. J. 1995. The birds of the Cape Verde Islands. British Ornithologists' Union, Tring, U.K.

Hazevoet, C. J. 1999. Fourth report on birds from the Cape Verde islands, including notes on conservation and records of 11 taxa new to the Archipelago. Bulletin Zoölogische Museum 17: 19-30.

Hazevoet, C. J. 2012. Seventh report on birds from the Cape Verde Islands, including records of nine taxa new to the archipelago. Zoologia Caboverdiana 3(1): 1-28.

Ratcliffe, N.; Monteiro, L. R.; Hazevoet, C. J. 1999. Status of Raso Lark Alauda razae with notes on threats and foraging behaviour. Bird Conservation International 9: 43-46.

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.

Click here for more information about the Alliance for Zero Extinction (AZE)

Explore HBW Alive for further information on this species

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View photos and videos and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Bird, J., Ekstrom, J., Shutes, S., Symes, A. & Taylor, J.

Contributors
Brooke, M., Donald, P. & Hazevoet, C.

Recommended citation
BirdLife International (2014) Species factsheet: Alauda razae. Downloaded from http://www.birdlife.org on 31/10/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 31/10/2014.

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.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Raso lark (Alauda razae) 0

Key facts
Current IUCN Red List category Critically Endangered
Family Alaudidae (Larks)
Species name author (Alexander, 1898)
Population size 250-999 mature individuals
Population trend Stable
Distribution size (breeding/resident) 3 km2
Country endemic? Yes
Links to further information
- Additional Information on this species