The population crash of the Aquatic Warbler in Hungary

Zsolt Végvári

Department of Conservation ZoologyHortobágy National Park - University of

Debrecen

10 November 2011Lithuania

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.

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.

Distribution

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

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.

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

Communication

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

Dominant:Carex melanostachionAlopecurus pratensisCarex ripariaElytrigia repens

Subdominant:Cicuta virosaRorippa cf. austriacaCirsium palustreCirsium oleraceumRumex hydrolapathumLysimachia nummulariaGalium uliginosum

Cirsium pannonicumLycopus europaeusEleocharis palustreGalium palustreCarex vulpinaSchoenoplectus lacustrisTypha cf. angustifoliaLytrum virgatumPolygonum hydropiperPoa palustrisPoa pratensisJuncus conglomeratesGlyceria fluitans (ditches)

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

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

Halophytes:Carex melanostachionCardamine flexuosaStellaria uliginosaEleocharis uniglumis

Other plant species:Alopecurus pratensisCarex vulpina Carex ripariaRanunculus polyphyllosRanunculus repensPoa palustrisPoa pratensisElytrigia repensUtricularia australisTypha latifogliaTypha angustifolia

Glyceria maximaGlyceria plicataGlyceria fluitansCalamagrostis neglectaEleocharis palustreCirsium palustreCicuta virosaRumex hydrolapathumLysimachia nummulariaGalium uliginosumLycopus europaeusRorippa austriacaSchoenoplectus lacustrisLytrum salicariaPolygonum hydrolapathumJuncus artratusPhalaris arundinaceaLemna minor

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). …

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

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

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

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

Ringing station AM or RAM or D.AM(2 lines) 66 or as

Ring number P1 …0…7…

MIN.MED.AMB.San SebastianP 1…0…7…

P 111111MIN.MED.AMB.ICONA MADRID

ICONAMADRIDXX 1111

P 111111ARANZADI

New Spanish schemes:

Old Spanish scheme:

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)

Thank you!

Best regards from Zsolt