Common Bittern: A Canary in Spain’s Wetlands
The common bittern (Botaurus stellaris) was chosen as Spain’s Bird of the Year in 2024 through a popular online vote organized by SEO/BirdLife. The poll drew more than 5,000 participants and placed the bittern ahead of its two finalists, the moustached warbler and the common spoonbill, underscoring the public’s concern for wetland biodiversity.
The fragile status of the little bittern reflects broader pressures on Iberian wetlands. Its habitat — reed beds that flood seasonally — is increasingly scarce in Spain, limiting local populations while the species still nests across several sites. Its potential distribution remains wider than the current occupied range, signaling both vulnerability and recovery opportunities in suitable wetland systems.
Wetlands cover roughly 85 percent of the area of concern, including globally recognized sites such as Doñana, Mar Menor, L’Albufera de Valencia, and Las Tablas de Daimiel. SEO/BirdLife highlighted this alarm in the 2022 report Ramsar Wetlands in Spain: on alert, noting that Spain will celebrate seven decades of Ramsar designation in 2024.
The same 85 percent figure reappears as a reminder of the commitment required to protect these crucial habitats. The little bittern is listed as Critically Endangered in the Red Book of the Birds of Spain and as Endangered in the National Catalogue of Threatened Species, reflecting the gravity of its conservation status.
Poor Wetland Management
The principal threat to Iberian bittern populations is the degradation and mismanagement of wetland spaces. Droughts intensify habitat loss, pushing birds from Guadalquivir marshes, Ebro Delta, and other key sites. On the occasion of SEO/BirdLife’s 70th anniversary, the organization urged that the bittern serve as a stark symbol of mismanagement in Spain’s wetlands. The bittern is described as a sister species to the crab egret, a lesser-known emblem that still reveals how gaps in protection undermine biodiversity and the wellbeing of local communities.
Advocates emphasize that time is running out. Reversing the decline requires a mix of climate resilience and reliable water security. The call to action from SEO/BirdLife centers on stronger governance and more effective regulatory frameworks to safeguard wetland ecosystems for both bitterns and people.
Historically, the little bittern was far more common at the start of the 20th century, but the population declined sharply in the latter half of the century. By 2011, breeding pairs in Spain were estimated at around 40 males, a sobering figure that underscores long-term risk.
Efforts to document distribution note that substantial populations historically accumulated in large reedbeds, including the Doñana complex and Empordà marshes. SEO/BirdLife notes that these expansive reed beds and the availability of prey such as fish, frogs, and crabs explain the species’ affinity for dense wetland mosaics, and highlight the importance of protecting expansive reedbed networks to sustain breeding and wintering requirements.
A Very Vulnerable Species
During winter, the bittern’s habitat needs become more flexible. It can utilize non-native wetlands such as rice paddies, reservoirs, abandoned gravel pits, and irrigation ponds. In winter, individuals have even been recorded along Cantabrian shores and the Mediterranean coast, showcasing seasonal shifts in habitat use that stress the need for adaptable management strategies across multiple landscapes.
The primary threat remains habitat degradation from drought and water mismanagement. The loss of expansive flooded reed beds directly reduces available prey and nesting sites, raising mortality risks. The Red Book notes the limited population size and heightened vulnerability to any additional pressures, including local water use and climate-driven changes in marsh ecosystems.
Additional challenges include reductions in surface water resources due to climate change and more frequent drought periods that degrade marsh habitats. When combined with high water demand and ongoing eutrophication, submerged areas shrink and reedbed quality declines, further endangering the bittern’s feeding and cover.
The species is highly sensitive to water pollution and eutrophication, which alter vegetation structure and reduce water transparency. Contamination from pesticides and spills adds another layer of risk given the bittern’s intermediary position in the food chain.
Actions Recommended by SEO/BirdLife
SEO/BirdLife frames biodiversity loss as an urgent issue in wetlands. The organization calls for stronger implementation of regulatory measures, including the Water Framework Directive and the Birds and Habitats Directives, as well as national planning tools that incorporate wetland protection into land-use planning.
Priorities include developing climate change adaptation strategies and restoration activities for wetlands. These measures align with international conservation targets and climate resilience goals, aiming to safeguard bittern habitats and support broader ecosystem health.
Throughout 2024, SEO/BirdLife plans to support science, conservation, education, and outreach efforts to raise awareness of the species and its conservation status, contributing to practical solutions on the ground.
Notable activities slated by SEO/BirdLife this year include:
- Requesting measures for species in management plans for areas of interest, such as the next Action Framework for Daimiel National Park.
- Updating information about breeding regions for the common bittern.
- Promoting recovery plans and strategies to protect threatened species associated with these habitats, with emphasis on the bitterns.
- Supporting the implementation of the 2030 Wetlands Strategic Plan.
- Developing a restoration demonstration project to improve habitat and encourage range expansion.
Further information on the Little Bittern is available through SEO/BirdLife publications and program updates, which provide context for ongoing conservation efforts and regional action planning to safeguard Spain’s wetland heritage.