What the hell is going on?

27 05 2015

“I’m an agent of chaos.”

– The Joker

We all have played the game consisting in trying to guess what will be the next “first-for” species to be seen in our countries and, most of the times, we all have failed. You have to wait quite long to see a longly-awaited species and, in the meanwhile, some other unexpected rarities are added to the country list.

These crazy sightings, like the French Kurdish wheatear, can be attributed just to freaky birds, while some others, like spring Collared flycatchers or Pallid harriers in the Iberian Mediterranean coast, come with strong easterlies, especially when the low pressures are placed over the Messina Strait. However, some of the most stunning influxes are hard to explain and we should probably look for answers at a worldwide scale.

This spring, the business is in the big numbers of Red-footed falcons and Icterine warblers almost all over the Iberian Peninsula, even inland, where these species are usually extremely rare. There are hundreds of them currently in Catalonia, where they are not rare but scarce (some years really scarce). This time, however, they don’t seem to follow the typical occurrence patterns. Easterly winds have not been that strong and the same species have appeared almost at the same time in both the Canary Islands and the NE Iberian coast. It seems therefore that they’ve chosen a more westerly route, probably crossing the Sahara through Mauritania and Morocco instead of the Nile valley.

El Hierro 1487

I’m sure this phenomenon has fulfilled several birder’s bar conversations but, since I’m surveying beaked whales at El Hierro (Canary Islands), I had to discuss the event with my friends through WhatsApp. Not a bad thing, since I re-read the conversation a couple of times while trying to find out what the hell is going on. Martí cleverly pointed out that both Icterine warbler and Red-footed falcon winter south of Zambia and both migrate N almost at the same time. Is it anything going on down there? And, if so, what could it be? An extremely tentative theory is an eastern galore in this southern wintering range. Keeping in mind the triangular shape of Africa, it could perfectly be that a difference of 50 km in a W-E axis in South Africa makes the difference between choosing the west of the Sahara route instead of the east.

El Hierro 1359

El Hierro 1053

I had 5 Red-footed falcons at El Hierro, maybe one of the westernmost localities they’ve reached, in what represents the second record for the island. There are dozens in the Eastern islands, together with the firsts Icterine warblers and Collared flycatchers ever found in the Canaries. Obviously not an anecdotal phenomenon, but a huge event that means something big has happened somewhere. It feels like two different phenomenon are implicated: “something” in the south of Africa that pushed them to the west and a hot haze in the Sahara that pushed them into the Atlantic Ocean.

El Hierro 1635

El Hierro 1633

Some of these birds are doing well here in the Canaries. They are busy preying on the African locusts that also came with the African haze. The grassy meadows are full of them and the falcons seem to spend the whole day catching them.

El Hierro 1020

However, some others died in Tenerife airport because they were hunting in the take-off lanes. Keeping in mind that probably several others just died in the middle of the ocean, the Red-footed falcon population could had suffered a strong decrease this spring. It would be interesting to research the causes of such a strange spring for this species and if it could be related to the western spread of some eastern species meant to be already happening.


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