The reproductive success of the Montagu’s harrier (Circus pygargus), a migratory bird endangered in Portugal and Spain, increased by 103% in 2025 due to the “Save the Montagu’s harrier” campaign implemented by the LIFE SOS Pygargus project in the national territory and in the Spanish autonomous communities of Extremadura, Galicia, Madrid and Castile and León, as announced in a press release.
According to the same source, “thanks to the conservation measures of this campaign, which include monitoring of individuals, awareness and involvement of farmers and local communities, as well as nest protection, rescue and saving of eggs and chicks, this species recorded a significant growth in reproductive capacity in the intervention areas of the project on the Iberian Peninsula.”
According to estimates by the project technicians and researchers, without these conservation measures, only 38% of nesting pairs laying would have managed to rear at least one flying juvenile. With the measures implemented on the ground, it was possible to assist many other pairs to achieve reproductive success, increasing to 77%, more than double, the number of nesting pairs with eggs that managed to produce offspring.
More than 600 monitored nests and 216 protected
During the 2025 “Save the Montagu’s harrier” campaign, 618 nests of this species were monitored in the project areas in Portugal and Spain, on agricultural lands and scrubland in mountainous areas, habitats where it nests. Of the monitored nests, 216 were the target of intervention to ensure protection both during agricultural works, such as mowing, and against predation by wild and domestic species, through the installation of protective fencing around them.
The Montagu’s harrier, which has an “Endangered” status in Portugal and “Vulnerable” in Spain, nests on the ground, mainly in agricultural lands with forage and cereal crops. This protection is essential to increase the species’ reproductive success, an action carried out in close collaboration with farmers, who play a central role in conserving these birds.
“The increase recorded this year in the reproductive success of the Montagu’s harrier is quite positive, considering that, according to data from the first census of the species conducted in Portugal in 2022-2023, this bird was at the brink of extinction, and in Spain the situation is also quite critical,” emphasizes Joaquim Teodósio, from the environmental NGO Palombar – Conservation of Nature and Rural Heritage and project coordinator, adding that, “although the scenario remains very worrying, the work of all partners, involving multiple sectors and communities, brings hope that this species will continue to fly across our fields.”
Rescued 68 eggs and 53 Montagu’s harrier chicks
From nests where field protection was not feasible, the project’s technicians saved 68 eggs and 53 chicks, through on-site rescue, to prevent their destruction or death. The eggs were transported to specialized centers, where they completed their development, and the chicks, whether rescued in the wild or from eggs saved in the field, underwent in Portugal a period of territorial adaptation at acclimation stations located on the Mirandense Plateau, in the municipality of Miranda do Douro, and in the south of the country, in the municipality of Castro Verde, vital areas for the species.
These stations were installed to receive rescued individuals, as well as to recover and bolster the population of this bird in a specific area, enhancing its philopatry—the tendency of a species to establish its breeding site in the same area where it was born or spent its first weeks of life.
Of the total number of rescued birds (eggs or chicks) that underwent an ex-situ care period and successfully completed their development, 97 were released back into the wild, contributing to increasing the Montagu’s harrier population in the years ahead.
72 birds tagged with GPS
In 2025, 72 Montagu’s harriers were also tagged with GPS/GSM devices, a crucial measure to detect threats affecting this species, as well as to improve on-the-ground conservation measures. The transmitters allow real-time monitoring of the tagged birds and provide valuable information related to behavior, migratory movements, nesting and foraging areas, risk factors, among others.
Predation and rural fires have a significant impact on reproductive success
Within the scope of the “Save the Montagu’s harrier” campaign, it was found that predation of eggs, chicks and adults has a significant impact on the species’ reproductive success. This predation is mainly carried out by other birds of prey, such as goshawks, owls and eagle-owls, as well as by corvids or storks, and also by mammals, notably foxes, among other wild species, or even domestic animals such as dogs or cats. Mortality due to agricultural machinery and adverse weather events, such as extreme heat, were also recorded.
Rural fires are another threat increasingly impacting this species, both in scrublands scourged by large fires this year in Portugal and Spain, and even in agricultural zones, where juvenile mortality was also recorded following fires in 2025, including in regions historically less affected by these events, such as Castro Verde in the Baixo Alentejo region.
AWARENESS, VOLUNTEERING AND MULTI-STAKEHOLDER COLLABORATION
During the campaign, dozens of farmers and rural agents were actively involved in protecting this species and were made aware of the essential ecosystem services it provides, notably agricultural pest control, having contributed decisively to its success. Dozens of volunteers also contributed to the campaign’s actions, helping monitor and protect the Montagu’s harrier.
Additionally, the project advanced with important multisectoral collaborations to conserve these birds, notably with the signing of a protocol with the Municipality of Carrazeda de Ansiães to strengthen the monitoring of the species in the Northern region.
“One of the project’s main objectives is to improve chick survival, increasing the species’ average productivity, i.e., the number of flying juveniles per nesting pair, from 0.6 to 1.5 – the threshold of population viability. With the conservation measures implemented this year, it was possible to surpass that value, reaching 1.98 flying juveniles per nesting pair,” highlights Pedro Horta, a researcher and project technician at Palombar.
“Now, the big challenge is to maintain these values in the coming years. Especially in areas less favorable for its nesting, from an environmental conditions point of view,” he concludes.
Cereals friendly to the Montagu’s harrier: second year of variety trials has begun
With the aim of increasing available habitat for the Montagu’s harrier, the project also intends to contribute to the growth of national cereal production, linking nature conservation to the promotion of agriculture. In this sense, it is a matter of “testing and selecting” cereal varieties more resistant and adapted to the reproductive cycle of this bird and to the Northern region. These are varieties that contribute to regenerative agricultural practices and with higher added value.
The second year of trials of the tested cereal varieties has already begun with their cultivation at Quinta do Valongo, belonging to the Mirandela Innovation Hub of the North Regional Coordination and Development Commission (CCDR-Norte) in Trás-os-Montes, and at the Elvas Innovation Hub of the National Institute for Agricultural and Veterinary Research (INIAV) in the Alentejo.
What these trials aim to do is to select varieties with a longer cycle and better adapted to the Montagu’s harrier’s reproductive cycle (considering that late mowing reduces mortality and increases the reproductive success of this species and other ground-nesting steppe birds that nest on the soil in agricultural fields); more adapted to the Northern region; with greater resistance to climate change and to major diseases and pests, and that protect biodiversity, promoting the balance of agricultural systems.
