As I write these lines, I’m excited and preparing for the start of a Calpe Conference here in Gibraltar. We have been organizing these events annually since 1997 and the conference, which starts on Thursday 4th July, carries the title that I even have chosen for this text. “Islands in the Sun” is about Macaronesia, the collective term used to define the Atlantic Islands of the Azores, Madeira, the Canaries and Cape Verde.
Island Canary Serinus canaria
I even have been fascinated by these islands for a very long time and I even have been lucky enough to have visited a lot of them. For many birders, these islands are places to go to for rarities, especially the Azores. My foremost interest lies in the endemic species and subspecies, trying to grasp why some species got there and others didn’t. More to the point, why did some that got there survive and others not?
Azores Bullfinch Pyrrhula murina
Looking at the Azores, we discover that just about half the birds turning up in these mid-Atlantic islands are Nearctic. When we take a look at the breeding birds, they’re all Palaearctic, either mainland species or endemics that evolved from mainland species. This immediately suggests that something about the conditions of those islands makes them suitable for Palaearctic birds but for those from the Americas.
Yellow-rumped Warbler Setophaga coronata – almost half the birds turning up on the Azores are Nearctic but none breed there
I often hear comments that the birds that reached the Macaronesian islands were trans-Saharan migrants that got drifted off target and settled there. Had this been the case we’d expect the breeding birds of those islands to be dominated by trans-Saharan migrants. When we take a look at it closely, we discover that this is just not the case. In fact, the breeding birds are overwhelmingly dominated by pre-Saharan migrants. That is, species that migrate down western Europe in autumn but rarely cross the Sahara Desert. They stay in south-west Europe and north-west Africa. Some can have populations that do cross the desert but these are small in comparison to those who don’t cross.
Tenerife Blue Chaffinch Fringilla teydea
Madeira Firecrest Regulus madeirensis
Fuerteventura Stonechat Saxicola dacotiae – this species is simply found on the island of Fuerteventura in the Canaries
This suggests to me that ability to achieve the islands is simply a part of the story. It’s more about endurance. When we take a look at Azores, Madeira and the wooded western Canaries, we discover that it has been the woodland birds and people who occupy a broad range of climates on the continent that dominate. This tells me that they’re the ones that best coped with life in a latest world, and so they made it. If we take a look at the arid eastern Canary Islands of Lanzarote and Fuerteventura, we also find a robust component of desert and semi-arid species from the mainland. Only on Cape Verde will we discover a component of Afro-tropical breeding birds. On the eastern Canaries they’re Palaearctic species.
Houbara Bustard Chlamydotis undulata
Cream-coloured Courser Cursorius cursor
All this tells me that we must always watch out about assumptions and making sweeping statements about bird distribution. The concept that the most highly migratory birds passing near the islands were the colonisers may sound intuitively correct however it is definitely wholly fallacious!
Madeira Kestrel Falco tinnunculus canariensis