The Canary Islands stonechat: questions to be answered (but not by me)

When I found out that BCM would be visiting the Canary Islands for our Easter field trip, I must admit I was surprised. I have always been interested in wildlife, but memories of family holidays to the Canaries are dominated by tourist beaches, feral cats and an empty desert viewed from camel-back. It turns out I was missing out on a lot! Firstly, the western isles (Gran Canaria, Tenerife, La Gomera, La Palma and El Hierro) reach higher altitudes and receive more rain, so are much greener – with forests, alpine vegetation and even snow-capped peaks. Moreover, the lower, drier eastern isles (tourists’ favoured Fuerteventura and Lanzarote) harbour their own interesting and important wildlife; the deserts aren’t so empty after all…

In hopes of returning to the Canaries for dissertation research in the summer, I headed to the Radcliffe Science Library to pick up a field guide from the stacks…and came across the Canary Islands stonechat (Saxicola dacotiae). While appearing (at least to the untrained eye) pretty similar to the European stonechat (Saxicola torquatus), the Canary Islands version is a distinct species, endemic to the archipelago. In fact, it is restricted to Fuerteventura, giving it one of the smallest ranges of any bird in the western Palearctic (Urquhart, 2010).

But it’s not that simple. A (disputed) subspecies, Bannerman’s S. d. murielae, was found on a group of islets north of Lanzarote in the early 20th century – although declared extinct since. As seen from the map below, this puts the whole island of Lanzarote in between the two known populations…did they once form a continuous population? Unfortunately, the Canaries have a very poor fossil record due to volcanism, but geological studies show that Fuerteventura and Lanzarote were once connected (Fernandez-Palacios & Whittaker, 2008) – so the stonechat’s absence from the latter is “surprising” (Martín & Lorenzo, 2001).

The Canary Islands (via Wikimedia Commons)

 

However, the fact remains that they are no longer found anywhere north of Fuerteventura. Except, that is, for a smattering of recent sightings in southern Lanzarote (listed in ‘Aves del Archipíelago Canario’ – Martín & Lorenzo, 2001). This piqued my curiosity: are they (re)colonising the island – and, if they can survive there, is it worth giving them a helping hand? The last update of the EU Action Plan for the Canary Island stonechat (2002) suggests that a reserve population on another island would be a good insurance policy against a catastrophe (presumably such as a volcanic eruption) threatening those on Fuerteventura. Despite this, the IUCN Red List only categorises the species as Near Threatened; its population is not severely fragmented, and it is found in over 10 locations – although it does appear to be declining. Therefore it suggests a need for comprehensive fieldwork.

‘Perfect!’, I thought. ‘I’ll go and assess the habitat suitability of Lanzarote’. Unfortunately, aside from the realisation that doing such a project would probably result in seeing a grand total of zero stonechats (and let’s be honest, ornithologists are driven by the desire to see birds as well as save them!), it turns out I had been beaten to it…10 years ago. Back in 2006, Dr Juan Carlos Illera and colleagues published a paper in which they compared sites in northern Fuerteventura, southern Lanzarote (where stonechats had been sighted) and Lobos islet in between. They found that Lanzarote is less shrubby and more stony (providing less cover of suitable habitat) and has lower abundances of arthropods following rains (providing less food for stonechat chicks). Lobos was even more unsuitable, although it would be interesting to extend the study to the islets north of Lanzarote, where the species is known to have lived.

The study also posed questions about the impact of introduced goats (whose grazing presumably decreases habitat quality) and feral cats (Canary Islands stonechats have been recorded in their diet; Medina & Nogales, 2009). The most recent IUCN report suggests that these threats are being considered, although there appears to be scope for more research. Urban development is also assumed to limit the species’ distribution, especially in the southern massif (Garcia-del-Rey, 2010). Later research also shows that the stonechat can use a wider range of habitat than previously thought: it can be found, albeit at lower densities, in areas such as traditionally cultivated fields, palm plantations and even urban areas (Seoane et al., 2011).

All of these points highlight the importance of taking humans into account. Brooks et al.’s (2008) review of avian conservation biology stated that socioeconomic aspects are often overlooked. For example, if the decision was made to (re)introduce birds to Lanzarote, how would Fuerteventurans feel about losing the status of a single island endemic? Would people of Lanzarote value it? What about tourists? Presumably most of them have no idea that the Canary Islands stonechat even exists. Those who visit protected areas may see an information sign about the species, but how can we inform those who want to go off-road driving and may be disturbing nests?

…all very useful questions to answer, but in this case I was thwarted by a combination of Canarian climate and the Oxford academic schedule. ‘Fuerteventura’ means strong winds, and it turns out that the trade winds are at their peak during the summer i.e. my fieldwork window. Unfortunately, this means that stonechats are very difficult to survey at this time. So, loathe to relegate my research to the wastebin, I’ve used this post to highlight a few points of interest and open research routes on the Canary Islands stonechat in the hopes of inspiring someone else to study this intriguing species. As for me, I’m working on an alternative dissertation proposal involving birds on the Canary Islands (I won’t give up on a summer with actual sun that easily). Watch this space…

the Canary Islands stonechat (by Frank Vassen, via Flickr’s Creative Commons)
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