At the border of ecological change: status and nest sites of the Lithuanian Black Stork Ciconia nigra population 2000–2006 versus 1976–1992
2008
Treinys, Rimgaudas | Lõhmus, Asko | Stončius, Darius | Skuja, Saulis | Drobelis, E. (Eugenijus) | Šablevičius, Bronius | Rumbutis, Saulius | Dementavičius, Deivis | Naruševičius, Vladas | Petraška, Antanas | Augutis, Danas
Recent trends in the European Black Stork Ciconia nigra population are geographically distinct: range expansion and adaptation to human activity dominate in western and central Europe, while declines—probably induced by landscape change—are reported in the east. We studied the large Lithuanian Black Stork population in the transition zone to explore whether, and how, the detrimental influences of recent Baltic landscape changes are balanced by the West European tendency of behavioural adaptation to human activity. Based on monitoring in sample plots, the current population was estimated at 650–950 pairs, indicating a significant decrease (possibly over 20%) during the last two decades. In comparison to the Latvian and Estonian populations, however, this decline is smaller, and the reproductive success remains at a high level [66% breeding success and 2.99 ± 0.97 (SD) fledglings per successful attempt, 2000–2006]; this north–south gradient suggests a climate-mediated impact of habitat degradation in the Baltic countries. The storks are also nesting closer to forest edges and in younger stands than 15–30 years ago, which has probably reduced the nest-tree limitation, as indicated by an increased use of large oaks. Thus, habitat degradation and adaptation seem to be taking place simultaneously in the Lithuanian Black Stork population, as was expected from its geographical location. In general, our study supports the view that, whenever possible, species conservation strategies and the use of indicator species should be geographically explicit.
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