A brighter future for a dull brown bird?

15th March 2021

The Raso lark Alauda razae is a small dull brown bird – but not just any small dull brown bird. Since its scientific description 120 years ago, the species has been confined to a single 7 km2 island, namely Raso, in the Cape Verdes. During the 2001-2019 period of our detailed study, the population has fluctuated between 60 and about 1500 individuals. Since 2011 the population has been at the upper end of that range, meaning the possibility of a translocation to another island to reduce extinction risk rose up the agenda.

The barren island of Raso where all the Raso larks in the world have lived since the species’ description © Michael Brooke

That possibility gained more enthusiasts when, thanks to a grant to SPEA (Portuguese BirdLife partner) from the MAVA foundation, a cat eradication began on 35 km2 Santa Luzia in 2017 as part of a wider ecological restoration of that island. From sub-fossils, we know that Santa Luzia supported Raso larks until about 500 years ago when the Cape Verdes first became inhabited.

In April 2018 37 larks were shifted across 25 km of blue sea from Raso to Santa Luzia. All were colour-ringed and breeding took place a few months later. A year later there was a top-up translocation of another 33 birds, again followed by breeding of some of the transferees. In late 2019 at least 40 birds remained on Santa Luzia. Remarkably their numbers had been supplemented by three colour-ringed females which had flown voluntarily from Raso to Santa Luzia. Perhaps such ocean journeys been happening for many years but only now had arriving birds prompted to stay by finding fellow larks on Santa Luzia.

Releasing larks on Santa Luzia, April 2018 © Jesús Martinez

Inevitably the Covid catastrophe interrupted detailed monitoring during 2020 when it seems – it would be premature to be wholly confident – the last cats have succumbed to trapping and poisoning. Nonetheless, thanks to decent rain, a crucial trigger of breeding, seven breeding pairs with 17 juveniles were detected on Santa Luzia in October.

Even more excitingly, a male chick ringed on Santa Luzia in November 2020, was found itself breeding in February 2021. Such quick progress to maturity had been suspected but never proven on Raso. It certainly confirms that the Raso larks find Santa Luzia to their liking, and there is currently every prospect that the new second population will prosper and the species will be downlisted from Critically Endangered to ‘merely’ Endangered.

Raso lark chicks close to fledging and anticipating a happy life on Santa Luzia.
It is not unusual for the species’ nests to be so exposed © Joana Bores

Further reading:

For more about the work of SPEA in the Cape Verdes, see https://www.spea.pt/projetos/protecao-de-especies-ameacadas-e-endemicas-em-cabo-verde/

For more details of how the translocations were carried out, see https://parksjournal.com/wp-content/uploads/2020/11/Brooke-10.2305-IUCN.CH_.2020.PARKS-26-2MB.en_.pdf

Michael Brooke and Joana Bores

Michael Brooke, Curator of Ornithology in the University Museum of Zoology, Cambridge, is a seabird enthusiast who nonetheless has visited Raso to study the thoroughly terrestrial larks every year 2002-2019.
Joana Bores is Marine Conservation Officer for SPEA, the Portuguese Society for the Study of Birds (BirdLife in Portugal).
We are both hugely grateful to many field assistants and to funders, especially Julian Francis, the MAVA Foundation, the Critical Ecosystem Partnership Fund (CEPF), and Sea Shepherd. Pedro Geraldes (SPEA) and the Cape Verdean NGO Biosfera have tirelessly combined to make the lark translocation possible. The project was approved by DNA, Cabo Verde’s environmental agency.