As I write these strains, I’m excited and getting ready for the beginning of a Calpe Convention right here in Gibraltar. We’ve been organizing these occasions yearly since 1997 and the convention, which begins on Thursday 4th July, carries the title that I’ve chosen for this text. “Islands within the Solar” is about Macaronesia, the collective time period used to outline the Atlantic Islands of the Azores, Madeira, the Canaries and Cape Verde.
I’ve been fascinated by these islands for a very long time and I’ve been fortunate sufficient to have visited quite a lot of them. For a lot of birders, these islands are locations to go to for rarities, particularly the Azores. My important curiosity lies within the endemic species and subspecies, attempting to grasp why some species bought there and others didn’t. Extra to the purpose, why did some that bought there survive and others not?
Wanting on the Azores, we discover that just about half the birds turning up in these mid-Atlantic islands are Nearctic. Once we have a look at the breeding birds, they’re all Palaearctic, both mainland species or endemics that advanced from mainland species. This instantly means that one thing in regards to the situations of those islands makes them appropriate for Palaearctic birds however for these from the Americas.
I typically hear feedback that the birds that reached the Macaronesian islands have been trans-Saharan migrants that bought drifted off target and settled there. Had this been the case we might anticipate the breeding birds of those islands to be dominated by trans-Saharan migrants. Once we have a look at it intently, we discover that this isn’t the case. In reality, the breeding birds are overwhelmingly dominated by pre-Saharan migrants. That’s, species that migrate down western Europe in autumn however hardly ever cross the Sahara Desert. They keep in south-west Europe and north-west Africa. Some could have populations that do cross the desert however these are small as compared to people who don’t cross.
This implies to me that means to achieve the islands is barely a part of the story. It’s extra about endurance. Once we have a look at Azores, Madeira and the wooded western Canaries, we discover that it has been the woodland birds and those who occupy a broad vary of climates on the continent that dominate. This tells me that they’re those that greatest coped with life in a brand new world, they usually made it. If we have a look at the arid jap Canary Islands of Lanzarote and Fuerteventura, we additionally discover a robust element of desert and semi-arid species from the mainland. Solely on Cape Verde can we discover a element of Afro-tropical breeding birds. On the jap Canaries they’re Palaearctic species.
All this tells me that we must be cautious about assumptions and making sweeping statements about fowl distribution. The concept that essentially the most extremely migratory birds passing near the islands have been the colonisers could sound intuitively appropriate however it’s truly wholly fallacious!
