# RES

The White Stork (Ciconia ciconia) is one of the most well-known European birds, distinguished by its recognizable appearance and important role in ecosystems. Unfortunately, during the 20th century, this species faced a significant population decline, especially in the western part of its range, leading to local extinctions in several European countries. In response to this situation, extensive reintroduction programs were initiated to restore populations in key habitats.

Zagreb Zoo actively engages 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 population of this species 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 Start 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 European species that experienced a significant population decline in the western part of its range in the early 20th century, resulting in local extinctions in several European countries. In response to this trend, extensive reintroduction programs were initiated to restore populations in 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:

• Historical and current genetic diversity of populations
• Impact of reintroduction programs on genetic structure
• Existence of possible glacial refugia in the Balkan region

The results revealed surprisingly high levels of genetic diversity and significant gene flow among populations, both temporally and geographically. Particularly interesting is the discovery that reintroduction programs have not left a significant mark on the genetic structure of today’s populations, suggesting a high level of natural mixing among individuals.

Additionally, observed differences between mitochondrial DNA and nuclear markers indicate sex-specific dispersal patterns, where gene flow is likely mediated by greater male mobility, while females show higher natal site fidelity.

This research contributes to a better understanding of population dynamics and evolutionary history of the White Stork, providing important information for future conservation efforts. It also raises new questions about the role of the Balkan region as a potential glacial refugium, which will be the subject of future research.

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. Results show that reintroduction programs had minimal impact on the genetic structure of current populations, indicating a high level of natural mixing through migration.

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

Partners: Lonjsko polje Nature Park, NGO AWAP

Project Start 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:

Given that the number of active nests in Čigoč, the first European stork village, decreased to nearly one-third from the early 1980s to 2000, it has become evident that the population of white storks is in decline. A reduced number of nests has also been recorded in other parts of the Lonjsko Polje Nature Park, which has been designated as an Important Bird Area (IBA) and Ramsar site.

Long-term monitoring has shown that the decrease in the number of storks returning to nest is proportional to the decline in the human population. To prevent further population decline, active conservation measures are needed, including strengthening the population of white storks through rehabilitation and the release of young individuals into the wild.

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.

From 2006 to 2014, through this collaboration between the Zagreb Zoo and Lonjsko Polje Nature Park, 37 white storks were released. These individuals were the offspring of storks rehabilitated in the zoo’s recovery center, which, unfortunately, due to the nature of their injuries, could not be returned to the wild.

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

Summary:

The “Strengthening the Population of White Storks in Lonjsko Polje Nature Park” project focuses on the restoration and enhancement of the white stork population through the rehabilitation and release of young individuals into the wild. From 2006 to 2014, Zagreb Zoo in collaboration with the Lonjsko polje Nature Park and AWAP released 37 individuals of white stork.