The population crash of the Aquatic Warbler in Hungary Zsolt Végvári Department of Conservation Zoology Hortobágy Nation

1. The population crash of the Aquatic Warbler in Hungary Zsolt Végvári Department of Conservation Zoology Hortobágy National Park - University of Debrecen 10 November 2011 Lithuania

2. Short history • The Aquatic Warbler has started to breed in Hungary in 1971 • had been searched by L. Szabó since the 1960s • Besides increased survey efforts no other breeding site than the Hortobágy National Park is known • The Aquatic Warbler population has increased with major fluctuations until 2000 and then declined with erratic peaks.

3. Legal situation • The species is strictly protected in Hungary. • The only known breeding site is protected in A and B zones of the Hortobágy National Park (47.5N, 21.0E; 80,000 ha) • the habitat requirement of the Aquatic Warbler is fully ensured: with habitat management focusing on the protection of the Aquatic Warbler. • The owner of the land is the Hungarian State, which also ensured the long-term sustainability of its local population.

4. Distribution • Total occupied area covers 10,000 hectares • Southern part of the national park • Core area covers 6,000 hectares • two satellite populations

6. Habitat selection • Majority of the Aquatic Warbler population breeding in the Hortobágy occupies alkaline wet grassland complexes • Characteristic plants: Alopecurus pratensis, Beckmannia eruciformis, Agrostis alba, Carex melanostachia • Such habitat types should be supplied with water in dry years and low grazing pressure by cattle is suggested. • Plans before the crash in 2011:The Department of Conservation Zoology of the Hortobágy National Park Directorate planned to start a PhD project studying the effects of habitat structure, management and human disturbance on the breeding success of the Aquatic Warbler. KOVÃCS, G.; VÉGVÃRI, Z. (1999): The Aquatic Warbler Acrocephalus paludicola in Hungary. Vogelwelt 120: 121-125.

7. Habitat management • In former times (until the 1950s) the whole of the marsh was completely mowed by hand, therefore providing no habitats for the Aquatic Warbler. • In its breeding area hay-cutting is limited and the water-level is artificially managed to ensure optimal conditions for successful nesting. • The water level in the breeding area (Kunkápolnás Marsh and its catchment) is annually adjusted to obtain optimal water conditions by controlling sluices, an activity performed by local rangers. • Extensive grazing by cattle is employed, which might also increase food availability. • Grazing by cattle and horses is applied for controlling natural succession, increasing food availability and decrease the probability of uncontrolled fires

8. Communication Local farmers are encouraged to perform extensive grazing in the breeding areas to control vegetation succession and reduce the probability of uncontrolled fire.

9. Plant species at Borsós, site 1b, ranked by coverage (Arcady):

10. Plant species at Borsós, site 1c (Arcady):

12. AWCT discussion 2004 (Hungary expedition): How different are the Hungarian habitats? People agreed, that habitats are not that different as expected, but have an alkaline and salty (not peaty) soil. Zsolt: We had also habitats of pure Juncus conglomerates tussocks (see published paper)! Alexander: Hungarian habitats are very similar to some habitats in the Styr and Stochid valleys. Zsolt: Hortobágy was Tisza floodplain up to the second half of the 19th century (former glacial spillways); whole Hortobágy is a salty alkaline former floodplain of the Tisza and it’s northern tributaries; the continuously moving Tisza river and tributaries formed this whole huge alluvial areas (soils like this have formed c. 26,000 years ago). Some conclusions of the following discussion: Similar areas could occur in central/southern Ukraine, Carex melanostachion also occurs there (Arcady). …

13. Population development • 1970: first breeding record • 1970–1990: steady, slow increase with minor fluctuations • 1990–2000 : strong increase • 2000–2010 : sharp decline with major fluctuations • 2011: first year with no breeding

14. Counting • 1970-2011: full counts are have been performed by the Ranger Service of the Hortobágy National Park Directorate and members of the Hortobágy Association for Nature Conservation. • 3-10 people

16. Crash events • 2003: fire caused by lightning → 30% of the breeding habitat burnt down after the breeding season • 2006: high flood of the Tisza River • 2010: high flood of the Tisza River

17. Possible explanations • As indicated by genetic studies, there might be metapopulation links between the core and the Hortobágy populations • Unusually fast and strong population changes after decline events indicate immigration -> Possible connections between the core and the local population • The habitat size and structure seems to be constant since the appearance of the species

21. Ringing station AM or RAM or D.AM (2 lines) 66 or as Ring number P1 …0…7… MIN.MED.AMB. San Sebastian P 1…0…7… ICONA MADRID XX 1111 P 111111 ARANZADI New Spanish schemes: P 111111 MIN.MED.AMB. ICONA MADRID Old Spanish scheme:

22. Suggested studies • Available data: • count data for each year and habitat patch (database under compilation) • Satellite images 1984 – 2011 will be available this year (image analyses to be done in the next months) • → habitat and population modelling (MaxEnt, R)

23. Thank you! Best regards from Zsolt