South of Villa San Michele rises Monte Barbarossa, on whose summit, about 100 meters above the Villa and 400 meters over the waters of the Bay of Naples, is the ruined fortress “Castello Barbarossa”. This mountain and its surroundings are an important resting place for migratory birds on their journeys every spring and autumn between their hatcheries in Europe and their winter areas in Africa. Previously the inhabitants of Anacapri hunted these birds in great numbers, and it was mainly to protect the birds that Axel Munthe bought the mountain in 1904.
The fortress, which today is the site of a bird observatory, originates in the Byzantine period, but is named after the 16th century Moorish admiral and pirate Keir-ed-Din, or “Barbarossa” (“Red beard”).
Since the Napoleonic wars the fortress has, however, not had any military significance. Organised ornithological studies on Capri started in 1956, when the Swedish Ornithological Society began fieldwork at the Capri Bird Observatory at Castello Barbarossa.
On the summit of the mountain, the fortress is well-located strategically for studies of resting and passing birds.
Since the early 80’s Italian ornithologists also work up here. Currently the Swedish ornithological activities on Capri are run by the Ottenby Bird Observatory on the Swedish Baltic island of Öland. Ottenby also carries out studies of migratory birds in their winter areas in tropical Africa, currently in Nigeria.
Capri is a station halfway between the hatcheries around the Baltic Sea and the winter areas south of the Sahara, but it is also located in the middle of the Mediterranean winter area for the birds that don’t fly any farther south.
The Italian studies on Capri were started by the bird conservation organisation LIPU, but it currently run by the bird ringing centre at the “Istituto Superiore per la Protezione e Ricerca Ambientale” in Bologna, as part of their “island project” “Progetto Piccole Isole” (PPI). Originally fieldwork at the Capri Bird Observatory was confined to spring migrations, and the Italian PPI fieldwork still is carried out during the topical birds’ primary passage between April 15 and May 15. From 1994 to 2004, however, the Swedish activities concentrated on the autumn period and for some years (2002-2004) birds that stayed over the winter were also studied. Today, however, the Swedish studies there are primarily special projects. These can be about how birds navigate during their long migrations flights, tests to monitor the occurrence of avian-borne diseases, or, in recent years, butterfly migrations.
Some species of butterflies and dragonflies migrate more or less regularly across the Mediterranean – and occasionally one of the notorious desert locusts turns up on Capri.
The migratory birds are trapped in nets, their species, gender and age are determined, and they are weighed and measured (for example winglength). Their “fat load”, which along with weight reveals how much “fuel” they have for the rest of their journeys, is determined according to a visual measurement scale.
The birds carry much extra fat in the autumn, en route over the Mediterranean and Sahara, but much less in the spring when they land on the island after finishing this long journey.
All birds are ringed and over the years many of these marked birds, when found again, have taught us where they come from and where they are going. For example, the Garden Warbler and the Spotted Flycatcher often breed in Finland, rest on Capri during their migration, and spend the winters in the Congo region. Results from the Capri Bird Observatory have been published both as special reports from the Ottenby Bird Observatory and the “Instituto Naziolane di Biologia della Selvagginia” in Bologna, and as scientific or popular articles in different national and international magazines.
In connection with the bird observatory’s 50th anniversary in 2006 a special edition of the Swedish scientific journal “Ornis Svecica” was completely dedicated to ornithological research on Capri, its history and results (no. 1-2, 2006).
Christian Hjort Ornithologist and head of the Capri Bird Observatory