Nesting oases helped increase bird reproductive success in Ria Formosa

A reproductive success rate of 90%, when, in the surrounding areas, “it was no more than 30%, in the best cases”, the ringing of hundreds of birds and a lot of environmental education, including the publication of a book for that purpose, are some of the achievements of the Bio-ilhas project, the results of which were presented in Olhão.

This project, promoted by the Algarve association Vita Nativa, with funding from the Viridia Association – Conservation in action, aimed to create safe nesting sites for the many species of birds that choose the Ria Formosa to breed.

At issue are species of birds that “would normally nest on beaches, in the dunes”, but that end up “looking for more inland areas”, due to the great human pressure that is felt along the coast, which begins “precisely at the time when that the nesting of these birds also begins”, he explained to the South Information Ricardo Correia, one of the members of the Bio-ilhas technical team.

Between Faro and Olhão, birds «look for areas adjacent to the Ria Formosa», because it «ends up filling up too much during very high tides and is also not the most suitable place, with a few exceptions. But the vast majority are not, because they are occasionally submerged».

Therefore, the choice for nesting is «in the salt marshes and their surroundings, as well as salt marsh areas, but higher marsh areas».

«What happens is that people also start to put more and more pressure on these places, either through walks or because they walk their dogs and let them out. We also have groups of wild cats that roam freely around the salt marshes and end up damaging the nests and eggs and even catching the young”, summarized Ricardo.

With Bio-ilhas, the Vita Nativa team created oases for nesting.

«We created limited areas, not accessible by people, cats, or any land animal. I’m talking about islands or combros – which, in reality, end up being islands too -, with the use of some walls that separate the tanks from the salt flats. We do this in traditional salt pans, because it is very important that water levels are maintained and, therefore, that the salt pan is in operation”, in order to replicate ideal nesting conditions.

«And the birds consider it a paradise, because they have no predation, except by aerial means, which is natural predation. They no longer have this artificial pressure», added Ricardo Correia.

In total, nine structures were created, namely four combro islands, one palisaded island and four floating islands, in salt flats and in the old lagoon of a WWTP between Faro and Olhão.

More than creating islands and rocks, isolating them from unnatural pressures, the Vita Nativa team carried out extensive monitoring work.

«We had a list of priority target species and a list of secondary target species. We did counts before and after the implementation of the islands, at control sites and in places where the islands were placed,” he explained.

And, both in the case of the main group and in the case of the secondary bird group, there was “an increase in numbers”.

This, «in itself, would be positive, because it is a sign that the birds have found a place of refuge there», but the success did not stop there, since «many nests were found», more precisely 109.

«And the main result is that the success of these nests, in terms of hatchlings leaving, was greater than 90%, while in other places around, where we also counted and followed the nests, it never reached 30%. %, in the best locations».

These results are even more important considering that there are some species that have a vulnerable status and are in “sharp decline”. One example is the Pied Plover, «which is experiencing great pressure across the entire Iberian Peninsula» and has now become vulnerable.

In the observations, made on 83 different days, 64 different species and around 380 thousand individuals were recorded. The Vita Nativa team also monitored 245 nests during the 2022 breeding season.

Also within the scope of this project, nine ringing sessions were carried out, where 465 birds of 20 different species were ringed.

In the nests, rings were placed on 65 chicks and 15 sightings of these birds were subsequently recorded.

Bio-ilhas also had an environmental education component, the most visible result of which is the children’s book “Pompoms with legs and curious children”, launched on the same day that the project results were presented.

28 actions were carried out with schools and 676 students were covered, four permanent information panels were placed and 6000 visitors were registered on the marked route in the Grelha salt flats, one of the places where islands were created.