Recovering or reinforcing the population of a species in a specific area is a process that must be done from the ground up. There is a system that, with certain birds, has shown very effective results. Known as “hacking” or controlled field breeding, it is a system directly related to the instinct of philopatry, which is the predisposition of an individual to establish its breeding territory in the same place where it was born or spent its first weeks of life. This behavior is particularly exhibited by birds of prey, and with it, very interesting results can be achieved in environments like the olive grove. Indeed, Olivares Vivos has demonstrated this with the implementation of four hacking programs carried out in 2018, 2019, 2020, and this year, allowing the establishment of new territories for these species.
But what is hacking? This system involves raising chicks in the environment where they will be released, placing them in nest boxes and feeding them in such a way as to avoid contact with the caregivers. This helps the chicks to identify that place as their birthplace. An appropriate feeding strategy during the first days of freedom helps them learn to find food and fend for themselves. Thus, once they form their own pairs, they will establish their territory in the environment where they grew up. “Hacking works especially well with birds of prey, yielding very good results. Just look at examples like the bearded vulture or the osprey,” explains Lise Pomarède, a technician for the LIFE Olivares Vivos+ project. However, she makes it clear that, before starting a field breeding, “it is necessary to ensure that the habitat conditions are suitable and, if they have deteriorated, to restore them. Additionally, it is important to verify that the potential threats that could have caused the disappearance of these species have been eliminated or are at reasonable levels. Once these two basic criteria are met, the release of individuals can proceed.”
In all the population reinforcement actions through hacking carried out by Olivares Vivos, the chicks came from Centers for the Recovery of Threatened Species (CREA) and were chicks accidentally abandoned by their parents or fallen from the nest (in some cases, due to heat strokes or storms).
What has Olivares Vivos achieved?
The recovery of biodiversity in olive groves has been and continues to be, along with the increase in agricultural profitability, the main goal of Olivares Vivos, an agricultural model that has found that, after its implementation, the flora and fauna of the olive grove can increase by up to 40%. In addition to the application of its agro-environmental scheme, other actions such as hacking have been added in specific locations.
Since 2018, Olivares Vivos has developed four hacking programs in two of its participating farms: Cortijo Guadiana (Úbeda) and Cortijo Virgen de los Milagros (Mancha Real). In both, two unused buildings (a former barn and an old electrical transformer, respectively) were converted into shelters and nesting areas for birds. In total, Olivares Vivos has reinforced the population of birds of prey with the following specimens:
Common kestrels (Falco tinnunculus), barn owls (Tyto alba), Eurasian scops owls (Otus scops), and little owls (Athene noctua). Four birds of prey that play a very important role in olive groves as pest controllers, having a highly developed instinct of philopatry and finding in the olive grove an ideal habitat for their existence.
This year, Olivares Vivos has once again carried out field breeding of various species at Cortijo Virgen de los Milagros. On this occasion, the protagonists of the action were four little owls, one Eurasian scops owl, and twelve common kestrels. They arrived at the cortijo in early May, all still with remnants of white down that quickly identifies them as very young chicks. Choosing the best nest boxes for each group (divided by species and brood), a feeding and care protocol was established to promote the proper development of each specimen.
“We fed the chicks every day, but always making sure they had no visual contact with us. We controlled the food we provided and checked how much they consumed each day. This way, we ensured that all the chicks had eaten well. This process is very important, especially in large broods like the five kestrel siblings, as there could be a dominant chick among them that wouldn’t let the others eat,” explains Pomarède, who has been in charge of caring for and monitoring the entire hacking process this year at the Casa de Vida de Monva.
For her, another relevant point to achieve the success of field breeding is maintaining proper cleanliness of the hacking boxes. “You try to reproduce as faithfully as possible the natural conditions of a little owl or kestrel nest. We provide them with a habitat where they can grow and feed, but we do not interfere in other details beyond removing the meat leftovers to avoid their accumulation because they can rot and generate infections or diseases in the chicks.”
Hacking and banding, inseparable actions
Like bread and oil, lovebirds, or having two employers and filing a tax return, hacking and bird banding are inseparable. Therefore, once a project of this type is initiated, the scientific banding of each specimen also begins. This way, when the chicks become independent, they can be identified by their bands, facilitating their tracking.
The four little owls, the Eurasian scops owl, and the twelve kestrels were banded just before being introduced into the hacking boxes, where they began to adapt to their new environment. Pomarède explains how, at first, these chicks are somewhat timid but gradually begin to show more character. “When you place them in the box, they stay in the same spot, barely moving. As the days go by, you see them moving more around the box, and when you approach, you hear warning calls, movement… The little owls, at first, would stay very still in a corner of the box, and before opening the exit, you’d almost always see them peeking out at the estate. That’s why making inspections is also very necessary to ensure the chicks are in good condition and maturing,” she adds.
Almost a week after being released into the hacking boxes, some specimens were already flying around the olive grove at Cortijo Virgen de los Milagros. “In the sky above our estate, we have always seen birds of prey like eagles and eagle owls flying, and now seeing Olivares Vivos reinforce the population of little owls, Eurasian scops owls, or kestrels has allowed us to learn about the ecosystem in which our olive grove develops and feel that its biodiversity is being completed and enhanced. It is a true privilege to collaborate with Olivares Vivos,” comments Luis Montabes, commercial director of Monva.
The nest boxes installed in each of the farms that are part of Olivares Vivos are occupied year after year. The success that these structures have demonstrated over the past few years in the Olivares Vivos model makes them an essential tool for recovering biodiversity in the olive grove. In fact, the year following the hacking carried out in 2018 with barn owl chicks at Cortijo Guadiana, those same specimens nested in the rehabilitated old barn on the estate.
