How much water needs a meadow bird habitat?

Transcription

1 How much water needs a meadow bird habitat? Experiences from LIFE Rewetting of Lake Dümmer Lowlands Heinrich Belting Lower Saxony Water Management, Coastal Defence and Nature Conservation Agency

2 Dümmer? Where the hell is that?

3 Location of the project area in Germany

4 Confluence of Hunte and Dümmer

5 drainage peat mineralisation- decline of meadow birds Shrinkage of peat layer

6 Aim is the regeneration of wet grassland and the conservation of meadow birds

7 SPA = ha Land purchase (2 500 ha) Euro Remaining private land

8 Flooding of fens during winter season by adjustable weirs Winter Spring Summer Autumn

9 Duration of flooding +/- permanent long term (2-6 months) short term (app. 1 month) without (only partly) drained (private land)

10 140 local farmers maintain wet grassland after breeding season has finished

11 Flowering meadows after perennial flooding: Marsh Marigold (Caltha palustris) Lady s Smock (Cardamine pratense)

12 Number of migratory birds is increasing 10 disappeared breeding species came back White Stork (Ciconia ciconia) Shoveler (Anas clypeata) Garganey (Anas querquedula) Spotted Crake (Porzana porzana) Corncrake (Crex crex) Ruff (Philomachus pugnax) Redshank (Tringa totanus) Short-eared Owl (Asio flammeus) Bluethroat ( Luscinia svecica) Sedge Warbler (Acrocephalus schoenobaenus)

13 Number of migratory birds is increasing 10 disappeared breeding species came back Remaining meadow birds have increased

14 breeding pairs Reversal of negativ trend

15 fledgelings per breeding pair Reproduction - from sink to source 1,6 Godwit (Limosa limosa) 1,4 Dümmer - South Dümmer - North 1,2 1 0,8 0,6 0,4 0,

16 time Duration of flooding (Dümmer South) not flooded no short term flooded December- March long term flooded December- May (July) duration no 4-6 weeks 6-8 months

17 nest sites habitat selection of nest sites (Dümmer South) 70% 60% 50% 40% 30% 20% 10% 0% not flooded short term flooded long term flooded

18 nest sites habitat selection of nest sites (Dümmer South) 70% 60% 50% 40% 30% 20% 10% 0% not flooded short term flooded long term flooded

19 nest sites habitat selection of nest sites (Dümmer South) 70% 60% 50% 40% 30% 20% 10% 0% not flooded short term flooded long term flooded

20 hatching success hatching success (Dümmer south; ) 100% 80% 60% 40% 20% 0% not flooded short term flooded long term flooded

21 potential fledging success Fledging success (Dümmer south; ) (total of hatched nests = 100 %) 100% 80% 60% 40% 20% 0% not flooded short term flooded long term flooded

22 Impact of flooding to invertebrates ( )

23 Mean weight of prey Area not flooded short term flooded long term flooded Ø dry mass of invertebrates 6,1 mg 4,7 mg 1,7 mg

24 Potential daily prey ingestion of godwit chicks Area number of prey invertebrates not flooded 2946 short term flooded 3835 long term flooded 10351

25 Potential handling time of foraging of godwit chicks Area handling time of foraging not flooded 6,6 hrs. / day short term flooded 8,6 hrs. / day long term flooded 23,2 hrs. / day

26 Potential handling time of foraging of godwit chicks Area not flooded short term flooded long term flooded handling time of foraging 6,6 hrs. / day 8,6 hrs. / day 23,2 hrs. / day Using only long term flooded areas for foraging chick survival would be extremely improbable

27 Impact of flooding to invertebrates ( )

28 First date of hatching ff.

29 What s behind it?

30 How much water do Godwits need? preference of not flooded areas for nesting (1. decade of rewetting) adults prefer flooded areas for nest sites (>15 years of rewetting) hatching success increases with flooding food availability of chicks decreases with flooding long term flooding can be a limiting factor of chick survival chicks prefer short term flooded areas for foraging short term flooding in winter is most profitable Mosaic pattern of different wetness is important

31 What have we learned? Wet grassland needs wetness Enough is better than too much Duration, watertable and extension of flooding depend on target species Mosaic pattern is most profitable for a high variety of species Flooding and rewetting collides with grassland farming Conservation targets are only achievable in cooperation with farmers It is a tightrope walk to combine profitable farming with conservation Our challenge in future is to balance these issues Without that balance, we will loose the farmers and their maintainance as well as the meadow birds

32 Thanks a lot for your kind attention!