No Eleanora's Falcon chicks survived this summer in Alegranza

It’s been a disastrous breeding season for the Eleanora’s Falcons in Alegranza, not one chick survived according to the biologists who have been monitoring the colony since 2006.

Eleanora's Falcon Chicks in AlegranzaEleanora Falcon

Photos: Courtesy of Lanzarote Active Club

Last Friday we went to a talk arranged by the Lanzarote Active Club and given by Dr Laura Gangoso at the Sands Beach Resort Hotel in Costa Teguise. We learned that of approximately 400 Eleanora’s Falcon chicks hatched on Alegranza this year, there were no survivors due to the phenology mismatch caused by a change in climate.

It’s understood that there are around 20,000 Eleanora’s Falcons in the world, of these approximately 18,000 migrate to the Mediterranean to breed. There are 285 breeding pairs of Eleanora’s Falcon in the Canary Islands, 135 of these migrate to Alegranza, 110 to Montaña Clara and 40 to the Roque del Este.

The biologists on Alegranza work with around 90 nests each year, collecting data by monitoring and tagging the birds. Each bird is given 2 tags, one metal and one plastic to identify them and a tiny blood sample is taken for analysis. There are 3 different colour morphs amongst the Eleanora’s Falcons, of the current population 70% are light, 29% medium and 1% dark. Some falcons breed in solidarity, other’s in a colony, there are benefits to both and a connection between the colour morph and nesting preference is being investigated, in Alegranza the nests are within 300m of each other.

With thanks to the advance of modern technology, we are starting to understand more about the migration route and breeding season of these birds. Originally it was thought that the falcons who breed in the Canary Islands flew back along the coast via the Med to winter in Madagascar, but the GPS tracking devices show that they fly across the African continent. These GPS trackers update every 3 seconds and with the magic of Google Earth the biologists can zoom in to specific areas where several birds have flown through to examine why they should concentrate in that zone. It takes the falcons around a month to make the 10,000 km journey, they can fly for up to 38 hours without stopping. Arriving in Alegranza during April and Madagascar in November.

Eleanora’s Falcons are an incredible species, they have adapted their diet and breeding season in order to nest here. Living on an insect diet in Madagascar, the falcons have adapted to hunting small birds when nesting in the Canary Islands, it takes a great deal of skill to catch a small bird in flight and one they teach their fledglings before migrating. A pair will produce 1-4 eggs and raise 1-3 chicks, the mean average is 2.5 chicks. The eggs are incubated for 28-30 days and the chicks can fly at 45 to 50 days old. During famine, the falcons may abandon a nest with eggs, but once hatched they don’t leave their chicks, they will kill siblings or their neighbours if necessary to feed a chick. It’s also been found that these falcons store food when the supply is plentiful, pantries of small bird carcasses have been discovered in previous years.

This year the Eleanora’s Falcons nesting in the Canary Islands have suffered a famine, as the lack of wind affected their food source. Normally the strong NNE Alisio trade wind present during the summer months blows small migratory birds off their course. Exhausted these birds land on Alegranza only to find there is no food for them and unable to combat the wind to leave the island, they then become the food source for the falcons.

The chicks can eat up to 5 small birds per day. It was found that when there is a plentiful food source, the birds stay close to the breeding site, when they are hungry the falcons travel to Lanzarote and as far as the African coast to find food. Unfortunately whilst the parents are away on long hunting trips, this leaves the chicks in the nest vulnerable to the hot weather and predators. The GPS trackers have shown that the hungry falcons risked flying into populated areas of the island this year, visiting hotels at night in Lanzarote to catch moths from the high powered lights situated in their gardens.

Apart from the lack of wind this summer, there was also no fresh drinking water in the reservoir on Alegranza. This was something the biologists could help with, they arranged for 8,000 litres of water to be shipped to the island, where they faced the reality of trying to pump the water from the boat up to the reservoir. The first mission was a failure, the hose was sinking into the sea and the pump wasn’t strong enough for the altitude, thankfully with buoyancy aids and a stronger pump the biologists finally were able to provide the much needed drinking water for the variety of birdlife breeding on the island.

Sadly we also learned of a dying Eleanora Falcon in Fuerteventura, a vet had reported the case to the biologists, this bird had been poisoned by insecticide. Another factor which affects the breeding season in Alegranza is day trippers, special permission is required to land on this island as it is privately owned and a protected area. Visiting the island during the main nesting season should not be encouraged, there are several months in the year when small groups with a guide would not affect the falcons and other species of birdlife present such as the critically endangered Egyptian Vulture.

The full extent of this year’s famine won’t be known until the return of the Eleanora’s Falcons in April, the biologists are worried that the birds may struggle to reach Madagascar in this weakened condition.