The disappearance of species from their natural habitat is a growing problem, which unfortunately means that the need for intensive management, including off-site conservation and relocation, is also increasing. For the relocation to be successful, risk factors must be removed from the area. In the context of re-establishment, it is important to assess the adaptation of captive-bred animals in the wild in order to improve release strategies and methods.
Madis Põdra’s doctoral thesis focused on the transmission of captive-bred European mink. The adaptation efficiency was evaluated as well as the impact of the American mink, the main threat. This was achieved by analyzing the prevalence of invasive species in Spain. European mink transmission was evaluated in two regions – the Salburua wetland in northern Spain and Hiiumaa in Estonia. On Salburua, the abundance of American mink was reduced before the release of European mink. In Hume, exotic species have been completely removed. 27 European Mink were released in the wetlands of Salburua (2008-2010) and 172 in Hiiumaa (2000-2003). To monitor the adaptation process of the released animals, radio tracking as well as live trapping were used. Researchers studied the survival of mink animals, their causes of death, their movements, and their dietary adaptation.
“My post confirms that the American mink is the main obstacle to the reintroduction of European mink,” explains Põdra. “If we are to successfully reintroduce European mink, the exotic species must be completely removed. European mink bred in captivity is able to adapt and survive in the wild. The first month or month and a half is the most important stage: at that time, the mortality rate of released animals is Relatively high. Later on, their behavior began to resemble that of a wild mink. “
This PhD thesis is particularly interesting because researchers have been able to assess adaptive efficiency in fairly great detail. Similar studies have been previously conducted on numerous occasions, but the majority of studies focus on the survival of released animals, often leaving the question of “why” unanswered. In Spain, Madis Pdra demonstrated that American mink had a significant effect on European mink transmission even if the abundance of exotic species was low and European mink was well prepared for life in the wild. European mink is known to compete with American mink for habitat, but through his research, Madis Pudra demonstrated that American mink is capable of destroying native species. The results obtained at Hiiumaa showed that captive-bred specimens are able to adapt to life in the wild, but the process is influenced by multiple factors such as the sex of the released animals and their living conditions in captivity. Additionally, the European mink’s tendency to move to unsuitable habitats after its release has been discovered along with the difficulties it encounters in catching prey. This indirectly affects their survival – although large predators are the direct causes of death, the ultimate causes may be maladaptive syndrome.
The moderators of the doctoral thesis are Tate Maran, Visiting Lecturer from the Estonian University of Life Sciences, and Teo Cove, Visiting Professor and Associate Professor of the Research Pathway at Tallinn University. Opponents are Professor Asco Lummus of the University of Tartu and John J.Ewen, Senior Research Fellow at the London Institute of Zoology.
The thesis is available in the ETERA digital environment of the TU Academic Library.