A new count of herons confirms it: drastically population reduction of these birds: the publication of a new national count of herons during the breeding seasoncoordinated by SEO/BirdLife, demonstrates the importance of wetlands and their vulnerability to the effects of climate change, where increasingly frequent and extreme droughts are expected. According to the publication The herons in Spain. Breeding population in 2020-2021 and counting method of the 8 species of breeding herons, only the blue heron falls outside one of the threat categories established by the IUCN. He common bitterndeclared Bird of the year 2024is the species that has the worst conservation status and is under consideration Critically endangered.
In the 2020 and 2021 breeding seasons, SEO/BirdLife focused on a new heron count. The control effort was important because it was carried out at a time when a pandemic was declared, greatly reducing people’s mobility.
The coordinated work of the network of employees and volunteers, the participation of some autonomous communities and technicians who oversee the heron populationsas the Doñana Biological Station or the Ebro Delta Natural Parkallowed us to take a new picture of the situation of this group of birds associated with wetlands.
Las heron populations They are strongly influenced by the fluctuations that occur in the flood level of the Mediterranean wetlands. But on this occasion, some of the factors that have determined this situation are the severe drought, especially in the period 2019-2021, which has affected their population, the disappearance of rice fields in certain areas, the poor conservation status of important wetlands such as Donana or the disappearance of certain agricultural and livestock practices in the case of cattle egret.
This is estimated according to the latest SEO/BirdLife census a population of 31,687-33,863 heron pairs in which it is distributed 531 breeding centers (384 colonies and 147 isolated pairs) in 1,007 locations prospected. Soria and A Coruña are the only provinces where this does not occur breeding heron.
Despite its wide distribution, more than half of heron population It is found in wetlands in the southwest of the peninsula, but the wetlands along the Atlantic-Andalusian coast and the entire Mediterranean coast are also important. Inland, the use of reservoirs and wetlands in the Tajo and Guadiana river basins is notable. However, the three basic wetlands are the Guadalquivir Marshes, the Ebro Delta Natural Park and the Albufera de Valencia, which are crucial for the conservation and maintenance of nature. heron populations.
Negative trend in the heron population
The evolution of all herons considered is clearly negative for the available count series. The population of 70,000 herons estimated in the 1980s increased to 60,000 in the decades 1990-2010 and ten years later the estimated population is only 30,000 pairs after a period of stability.
The most endangered species is the bittern, which has only 18 occupied areas in 6 communities.. The most common types, cattle egret, also registers a noticeable decline that brings it to a threat situation considered “vulnerable”. The garza really The species is widely distributed throughout the territory, but this census confirms the colonization of Asturias, recently in the Balearic Islands and Melilla, and the number of breeding sites is extensive. The garceta grandea heron that has been breeding in Spain for a few years has also slowed its growth and is considered near threatened.
The bad situation of wetlands in Spain
The report Ramsar wetlands in Spain. Watchful prepared by SEO/BirdLife in 2022, shows the pressure this brings wetlands, whose habitat quality causes ‘high’ or ‘very high’ pressure due to human activities. This situation means that a total of 85% of the Ramsar wetlands It shows a worrying conservation status (18% fair status, 29% poor and 38% very poor).
The report also shows that 22% of wintering and migratory waterbird populations pose significant conservation concerns, a figure that rises to 63% in the case of waterbird populations that use Spanish wetlands for breeding. In fact, almost three in ten bird species that depend on these ecosystems are critically endangered.
Status of herons according to IUCN threat category
Common Bittern — Critical danger
Common jackhammer – Vulnerable
crab egret – Vulnerable
Cattle egret – Vulnerable
common egret – Vulnerable
Great Garceta — Near threatened
Garza really – Least concern
Garza roof rack – Vulnerable