# RES

The White Stork (Ciconia ciconia) is one of the most well-known European birds, known for its distinctive appearance and vital role in ecosystems. Unfortunately, throughout the 20th century, the species experienced a dramatic population decline, particularly in the western part of its range, resulting in local extinctions across several European countries. In response, extensive reintroduction programs were launched to restore populations in key habitats.

Zagreb Zoo plays an active role in the protection of the White Stork, contributing to the preservation of biodiversity through research, rehabilitation, and education. Through various projects, the zoo not only helps strengthen the species’ population but also gains new insights into its genetic structure and ecological needs. These efforts contribute to raising awareness about the importance of nature conservation and the development of sustainable strategies for the protection of the White Stork in Croatia.

Project Name: Genetic Research of White Stork (Ciconia ciconia) Population: Impact of Migration and Reintroduction Programs

Partners: Royal Zoological Society of Antwerp; Murdoch University, School of Biological Science and Biotechnology, Murdoch, Australia; Royal Zoological Society of Scotland; Poznan University of Life Sciences, Poland; Lund University, Sweden

Project Commencement Year: 2016

Status: Finished

Species: White Stork (Ciconia ciconia)

IUCN Red List Status: Least Concern (LC)

Species Status in Croatia (Red Book): Least Concern (LC)

Project Details:

The White Stork (Ciconia ciconia) is a distinctive species native to Europe, which faced a significant population decline in the western part of its range during the early 20th century. This decline led to local extinctions across several European countries. In response, large-scale reintroduction programs were launched to restore populations in the affected areas.

The research focused on characterizing the genetic structure of White Stork populations before and after the implementation of reintroduction programs. Using modern molecular methods (mitochondrial DNA and microsatellite analysis), we analyzed:

• The historical and current genetic diversity of populations
• The impact of reintroduction programs on genetic structure
• The potential existence of glacial refugia in the Balkan region

Our findings revealed unexpectedly high levels of genetic diversity, along with significant gene flow across both time and geographic space. Notably, reintroduction programs did not have a discernible impact on the genetic structure of current populations, suggesting that natural mixing among individuals remains prevalent.

Furthermore, differences observed between mitochondrial DNA and nuclear markers point to sex-specific dispersal patterns. Specifically, gene flow appears to be driven primarily by higher male mobility, while females exhibit stronger fidelity to their natal sites.

This research enhances our understanding of the population dynamics and evolutionary history of the White Stork, offering valuable insights for future conservation efforts. It also raises intriguing questions regarding the potential role of the Balkan region as a glacial refugium, which will be explored in future studies.

Summary:

Research on the genetic structure of White Stork (Ciconia ciconia) populations revealed surprisingly high levels of genetic diversity and significant gene flow among populations, despite historical local extinctions and reintroduction programs. The findings suggest that these reintroduction programs have had only a minimal impact on the current genetic makeup of populations, highlighting the strong role of natural migration in maintaining genetic connectivity.

Project Title: Strenghtening of the White Stork Population in Lonjsko polje Nature Park

Partners: Lonjsko polje Nature Park, NGO AWAP

Project Commencement Year: 2006 – 2014

Status: Finished

Species: White Stork (Ciconia ciconia)

IUCN Red List Status: Least Concern (LC)

Species Status in Croatia (Red Book): Least Concern (LC)

Project Details:

The number of active stork nests in Čigoč—the first European stork village—declined to nearly one-third between the early 1980s and the year 2000, clearly indicating a significant decrease in the white stork population. A similar decline in nest numbers has also been observed in other areas of the Lonjsko Polje Nature Park, a site recognized both as an Important Bird Area (IBA) and a Ramsar site.

Long-term monitoring has revealed a strong correlation between the decline in returning storks and a decreasing human population in the region. To halt this trend and support population recovery, proactive conservation efforts are essential. These include measures such as rehabilitation and the release of young storks into their natural environment.

The project “Strengthening the Population of White Storks in Lonjsko Polje Nature Park” focused on the conservation of the white stork (Ciconia ciconia) through active restoration and enhancement of its population in the Lonjsko Polje area, known as one of the key habitats for this species.

Between 2006 and 2014, a collaborative effort between the Zagreb Zoo and Lonjsko Polje Nature Park led to the release of 37 white storks. These birds were the offspring of storks undergoing long-term care at the zoo’s rehabilitation center. Although their parents could not be returned to the wild due to permanent injuries, their young were successfully reintroduced into nature.

This project represents an important step in the conservation of biodiversity and the protection of this species in its natural habitat.

Summary:

The project “Strengthening the Population of White Storks in Lonjsko Polje Nature Park” aims to restore and support the white stork population by rehabilitating and releasing young birds into their natural habitat. Between 2006 and 2014, the Zagreb Zoo, in partnership with Lonjsko Polje Nature Park and AWAP, successfully released 37 white storks back into the wild.