Alauda razae 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Alaudidae

Scientific Name: Alauda razae (Alexander, 1898)
Common Name(s):
English Raso Lark, Raza Island Lark, Razo Lark
French Alouette des Iles du Cap-Vert
Taxonomic Source(s): Cramp, S. and Simmons, K.E.L. (eds). 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ac(iv)+2ac(iv) ver 3.1
Year Published: 2017
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Brooke, M., Donald, P. & Hazevoet, C.
Facilitator/Compiler(s): Benstead, P., Bird, J., Ekstrom, J., Shutes, S., Symes, A., Taylor, J., Westrip, J., Martin, R
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.

Previously published Red List assessments:

Geographic Range [top]

Range Description: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 1,558 in November 2011, before declining to 855 in November 2015 (M. Brooke in litt. 2016).  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.

Countries occurrence:
Cape Verde
Additional data:
Estimated area of occupancy (AOO) - km2:3Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:4
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):50
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The population was estimated at 1,558 individuals in November 2011 before declining to 855 in November 2015 (M. Brooke in litt. 2016).  This equates roughly to 570 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.

Current Population Trend:Stable
Additional data:
Number of mature individuals:250-999Continuing decline of mature individuals:No
Extreme fluctuations:YesPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and 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.

Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):6
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): 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 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 [top]

Conservation Actions: 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.  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.  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.  Undertake eradication of cats on neighbouring Santa Luzia and re-establish Raso Lark there (P. Donald in litt. 2016).

Amended [top]

Amended reason: Map revised.

Citation: BirdLife International. 2017. Alauda razae (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T22717428A111113319. . Downloaded on 19 July 2018.
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