Raptors and Seabirds migrating in the Straits of Gibralter
11/3/15 • Written by Julianne
Hundreds of Griffon Vultures (above photo), spiraling up to test the air currents, deciding to migrate or not. Several thousand Cory's shearwaters leaving the Mediterranean. A few Balearic shearwaters entering the Mediterranean. Flocks of linnets swirling to the water edge and circling back--waiting to get the courage to cross. Other eagles, vultures mixed with the griffons. Other small birds getting ready to cross or settling in for the winter.
Bird migration at the Strait of Gibraltar. It is one of the remarkable natural phenomena in the world. It is something I have wanted to witness for so many years. Since the straits form the narrow passage between the Mediterranean and Atlantic it is a chokepoint for seabird flights in and out; it also is the chokepoint for landbirds moving north and south. I can't think of anywhere else in the world which has such migration wealth.
Today, we visited Tarifa, Spain, the southernmost point of mainland Europe to watch whatever may be happening birdwise. We both have rave rewiews for Birding the Straits tour company whose staff have provided us a great experience. Contact them if you will be in the area. I will be going out with them again while we are here.
Seabird Migration
We visited the Isla de Palomas first which is joined to Tarifa by a causeway. The isla holds the lighthouse and a seawatch observatory (white shelter in photo). Spanish observers are present constantly during this season to keep track of the waterbirds like shearwaters, gannets, puffins or any others that may be passing. The Isla is also a holding point for human migrants from Africa while their asylum cases are heard, meeting another of my interests.
Cory's Shearwaters
While we were there for about an hour, the one counting Cory's shearwaters was clicking the counter constantly. He estimated that about 3,000 per hour were passing on their route from the Mediterranean out to the Atlantic where they will spend the winter. From here they go south along the African coast then cross toward South America. These birds are rarely visible from shore since they skim along the water and catch fish, rarely resting on the waves. With powerful scopes and a narrow channel, they were visible as a stream of black birds just above the waves.
Balearic Shearwaters
The smaller Balearic shearwater is moving too although in fewer numbers. It is even harder to see them as they are about half the size and fewer scattered along. These birds spend the summer months in the Bay of Biscay fishing and skimming along the waves out of sight of land. Now they are returning to the Mediterranean--to the Balearic Islands, off the Spanish coast--to breed in the winter. An unusual pattern. There are only about 17,000 of these birds in the world but that is more than previously thought. About 3000 nest in the Balearics and only recently have other populations been identified.
For us, we could identify them because they were small (about 12" length) black birds crossing our scopes going in, not out. Although we identified only a few, the seawatch counters said about 20 or so per hour were moving through. Since large seagoing ships were passing both directions, our birds showed up as black moving dots against the sides of ships. Then we could get a scope on them.
Linnets
Linnets are a small sparrowish bird which migrates north in spring and south in fall. My first linnet sighting was at Cape Clear Island, Ireland, the first place they enter the northern sites where they will breed. In Ireland the males had rosy colored sides and head; now they are all streaky brown. They go as far north as Norway and Iceland and a few were still present in Iceland when I was there in September. Today, flocks of 20-30 would circle up, swirl around, check the wind and settle back down in the brush and rocks at our feet. Not ready. Maybe waiting for a wind from the north to help them along. Probably also waiting for dark in order to avoid becoming lunch for the numerous yellow-legged gulls who could pick them off if over the water.
Raptor movement
Although September is the biggest month for raptors to cross the Straits, one of the largest and most dramatic raptors is only moving now--the Griffon Vulture. We went from Tarifa east along the coast to a hilltop observatory where we could watch the surrounding hills as well as the strait hoping to see the vultures and any other eagles, hawks, falcons in the area. We were rewarded. In addition to hundreds of vultures, we also saw booted eagles, kestrels, Spanish imperial eagle and Bonelli's eagles in ones and twos.
While we watched, small kettles of vultures rose up, circling. The Griffon is approximately the size of a California condor (8-9 ft. wingspan) and fills a similar eco-niche. Throughout the Iberian peninsula and into France, the vultures live and breed, eating the carcasses of cattle which range freely throughout much of the area. Some stay in the area year-round but young birds migrate to Africa where they distribute themselves around the desert and plains for the winter. The day before about 3000 crossed the strait and we worried that few would still be around. But our first sighting around noon was a few hundred; later as the warm thermal air rose, more and more vultures rose too forming circular "kettles" and then streams of birds. Maybe several hundred in our view at any one time. A birdwatch monitor estimated that about 800-1000 were present overall.
They are dramatic, stunning birds; the sun and light were perfect--my eyes were filled with beauty. Our photos below show the rising and formation of the streams of birds. While we were there, they did not cross the water but streamed along the coast--frightened to head out. Waiting for a helpful wind, we think.
Windfarms and bird migration
This area is windfarm central. It is one of the first places in Europe where windfarms were sited and it has enough wind to power the world, in my opinion. Atlantic to Mediterranean or reverse--plenty of wind. Since it was among the earliest windfarm areas, it was not known that there would be problems with bird migration until the windmills were operation. So this is an area where the bird deaths were significant.
Since those early days, some measures have been taken to mitigate the bird loss. New windfarms are placed away from bird routes, for example. Here, though, they could not feasibly move the ones already in place so they have taken other measures. During migration in spring and fall, they have bird monitors in the hills to see is streams of birds are coming to any particular location. If birds are coming and low enough to be harmed, the monitor calls in the information and those windmills are turned off until the birds pass. We met one of the monitors who reported that the Griffons and other migrants were not in danger at the time.
Other shots in the area
Photos by Nancy.
Specific bird photos from National Audubon Society and Royal Society for Protection of Birds.
Text by Julianne.
Pretty good grafitti stencils and posters for the International Day of Eliminating Violence Against Women (UN declaration for November 25).