The Dehesa is often mentioned by birders and contributors to the ABS website and Facebook pages, but for those who are not sure what is, I’ve written this short piece by way of an introduction.
Dehesa (or Montado) as it’s called in Portugal is one of Europe’s and arguably the world’s great natural habitats. It stretches across southern and central Iberia between the great Sierras.
It is an old anthropogenic ecosystem, one carved from earlier fully wild habitats. It is rich in biodiversity, cultural and archeological artefacts as well as being a rich source of food and materials for us humans.
Technically it is an agrosilvopastoral ecosystem; in other words, one that is grazed, is forested and provides commodities such as milk, meat, olives, etc.
It has been described by the European Forum on Nature Conservation and Pastoralism (EFNCP)as the “best example of man and nature working together in the world”. No small claim, but one I’m inclined to agree with.
I first came across the Dehesa and the EFNCP when I was head of conservation for The New Forest, a national park in southern England. In some ways The New Forest is similar to the Dehesa, though on a smaller scale. These similarities include the following:
They are old landscapes and ones that have been managed extensively for hundreds or thousands of years, which has created a rich biological, social and cultural identity.
The main managing agents are large free ranging domestic herbivores, ponies in the New Forest and cattle (mainly) in the Dehesa. In addition there are good numbers of wild herbivores too, notably various species of deer.
The ecological structure is what we would call in the UK, open wood pasture, that is, an intimate admixture of ancient woodland interspersed with glades and more open pasture. The silvicultural component has a high percentage of old and veteran trees, with all the important deadwood habitat that comes with that age.
The grasslands and glades are unimproved, semi-natural and species rich, often located over nutrient poor mineral soils.
They are abundant ecosystems, rich in biodiversity and because of their extent, approximate the natural climax vegetation of their regions. Though a noticeable missing element are the larger apex predators such as wolf, though Iberian wolf is present, in small numbers towards the north of the Dehesa complex.
The dominant tree species are Oak (Quercus spp) particularly Quercus suber, cork oak, Q pyrenaica, Pyrenean Oak and Q Ilex, the great holm oak. In the southern part of the range Q Suber is mixed in with wild olive Olea Europea sylvestris.
Adding to this diversity, permanent and seasonal rivers wind through the oaks and here one finds dense riverine woodland composed of alder, Alnus spp and Ash, Fraxinus spp.
Like any extensively grazed habitat there is a natural gradation from open grassland to high open forest and within that ecocline one finds a rich assemblage of mixed dense scrub.
It is precisely because of this inherent habitat heterogeneity and the retention of old trees within the Dehesa that we find one of the richest densities of breeding bird species in Iberia and indeed within Europe.
Perhaps the most famous and emblematic of these birds is the magnificent Spanish Imperial Eagle, (Aquila adalberti), and the Dehesa is the stronghold for this species as it slowly recovers from a low point of just 30 pairs in the 1960’s.
Much of this landscape is in the hands of large private estates, often stretching for thousands of hectares (part of the inheritance from the Roman Latifundia system of land management) and as such this favours the shy and easily disturbed Spanish imperial eagle.
This eagle was formerly a specialist hunter of the rabbit; however, since the deliberate introduction of Viral Hemorrhagic disease its main prey item has been reduced by 90%. Fortunately, the Dehesa offers a variety of other suitable prey species and the eagle now predates game birds, water birds as well as small mammals.
The population crash of the rabbit has also affected another magnificent inhabitant of the Dehesa, that rarest of big cats, the Iberian Lynx. Like the eagle its numbers are slowly increasing.
This venerable habitat is more than just a collection of one or two special animals though, as the mature trees support an incredible diversity of insect species, including many rare and endemic beetles that constitute the deadwood fauna.
In turn this leads to a richness of opportunity for the passerines as they are afforded multiple nesting possibilities in cracks and holes as well as an abundance of prey. The Dehesa in spring is a riot of noise and movement as the small birds establish and defend territories.
In addition to the private estates, there are large areas of publically owned land, often belonging to the municipalities. This land is part of the great network of the commons, grazed since pre-Roman times by the villagers and peasants.
Through these pass the cañadas; the ancient drove roads used in the practice of transhumance – where livestock and herders move in search of rain and fresh pasture, a form of farming without frontiers. The cañadas thus became corridors connecting adjacent, though separated areas of high biodiversity.
As can be imagined from the above, the Dehesa is an incredible place to visit for the naturalist and some of the main bird species associated with it, though not exclusively includes:
Bonelli’s Eagle, Black-winged Kite, Black Vulture, Black Stork, Common Crane, Rufous Bush Chat, Wryneck, Eagle Owl, Iberian Magpie, amongst many others.
However, within this ancient ecosystem, change is afoot, cork has been one of the most important products derived from the Dehesa and almost all of the world’s cork comes from these forests. In the last ten years there has been a growing demand for glass and metal screw tops for wine bottles – the single most important market for that cork. With a decrease in demand comes the possibility of these forests becoming more profitable as intensively managed landscapes, something that is anathema to all that is the Dehesa.
But, for all us who love birds and wildlife, there is another opportunity, that of bird tourism. Small companies that offer guided bird and nature tours in the Dehesa are growing, it is good to promote and support these local sustainable companies.
However there are other things that we can do to help the Dehesa, including drinking more cork stoppered wine!
In addition to wine, some of the finest foods of Iberia come from here, honey, cheese, ham, olives to name a few – keep an eye out for products that are certified as coming from the Dehesa.
Let’s celebrate this incredible piece of natural and human history, by birding within it, toasting it and feasting upon its many delights.
Article: Neil Hill – ABS Conservation Officer
Photos: Neil Hill (Cover photo Peter Jones)
Note: The views expressed in articles are those of the authors, and are not necessarily those of the Society.