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In the past centuries, many of the Eurasian lynx populations declined and finally disappeared. In Poland, only two populations survived until the 20th century. In the 90s a new population was reintroduced in central Poland but presently, its fate is considered uncertain. While the recurring observations of lynx in the area confirm its presence, they are insufficient to evaluate the state of this population. Therefore, using a population viability model and the reintroduction program data, we analyzed the ambiguities in the vital rates assessments to find the most likely scenario for the development of the population since its reintroduction. Finally, we modeled different options to improve the survival chances of this one and possibly other small populations. Estimated parameters result in a declining population. In the majority of the simulations, lynx populations go extinct within 20 years. This can be improved by reintroduction or natural immigration of new individuals every 4 years, but only if the new individuals arrive within a short period of time after the initial reintroduction. Also, longer time intervals are insufficient to elevate the median time to extinction beyond 50 years. Separately, moderate changes in reproduction or survival rates have only a marginal effect on the population’s survival. Decreasing only the impact of mortality would increase this population’s persistence time, but not ensure its long-term survival. However, decreased mortality in combination with immigration should result in much more successful population development. With higher longevity and release every 4 years the population is more successful even if the new individuals start entering the population up to 20 years later. Even less frequent immigration combined with enhanced longevity still improves survival. Combined adjustment of individuals to their environment and regular immigration provide the best chances of long-term survival. One or both of those factors could explain why lynx is still present in the area. |
