Ornis Hungarica. vol.12-13. (2003) p.169-183.
Integrated population monitoring of sand martin riparia riparia - an opportunity to monitor the effects of environmental disasters along the river Tisza
From January to March 2000, the entire length of the River Tisza suffered an appallingly serious environmental disaster when the collapse of tailings dams belonging to upriver Romanian gold mines caused severe pollution by cyanide and heavy metals. This pollution was the direct cause the death of flora and fauna in the Tisza along its length and threatened the entire ecosystem of the river, one of the last remaining natural major rivers in Central Europe almost free of large-scale man-made developments. The river Tisza is such an important breeding and roosting area for large populations of several insectivorous and piscivorous bird species that several Important Bird Areas (IBAs) have been established along its course. Most of these species are migrants that fortuitously happened to be elsewhere in their travels when the pollution occurred, but the scale of the problem was such that delayed impacts can be expected. As it happens, long-term integrated monitoring work on the Sand Martin Riparia riparia breeding population along the river Tisza in Hungary has been running since 1986 under the aegis of MME and BirdLife Hungary. This project also happens to monitor the population size and distribution of Kingfisher Alcedo atthis and so was well placed to begin comprehensive monitoring of the short-, mid- and long-term effects of this disaster. The breeding populations of these two species along the river Tisza depend predominantly on the supply of their food, the fauna of the river and its flood zone. The two species, by macabre good fortune, happen to be the ideal models for studying the effects of the disaster on insectivorous and piscivorous birds. Detailed studies in 2000 following proven protocols, such as fieldwork and chemical analysis of the feathers, revealed that the pollution has had no measurable effects on population sizes, distribution and reproductive success, and that the level of heavy metals in the food chain of insectivorous birds did not increase. However, precedent and the scale of the disaster suggest that the lack of immediate effects means that there may well be secondary effects in the longer term from subsequent events, such as floods and droughts. The disaster has brought greater international awareness, which may help to reduce pollution or make such incidents less likely. Our investigation underlined the importance of monitoring in these kinds of habitats, because it showed that some assumptions about the consequences of the accident were wrong; in the absence of data, there is a risk in such circumstances of misinterpreting the outcome.