Patterns of predation on ground nesting meadow birds Mønstre i prædation på reder af jordrugende engfugle. Henrik Olsen Sektion for Zoologi

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1 Patterns of predation on ground nesting meadow birds Mønstre i prædation på reder af jordrugende engfugle Henrik Olsen Sektion for Zoologi

2 Meadowbirds at Vestamager Breeding numbers Rødben Strandskade Vibe 5 years of natural succession a new landscape =>=> fewer breeding meadowbirds

3 1991

5 Breeding success at grazed areas Lapwing nests (n=145 ) Shell remains (n=23 reder) Hatched 2% Aband. Trampled 2% 1% Depredate d 77% No remains 51% Bird 32% Mammal 17%

6 Shell remains Mammalian Avian.?

7 Temperature logging in lapwing nests

8 Time of predation 8 a 1998 (n=28) N= 92 nests No. of nests b 1999 (n=41) 8% of all nest were lost during night No. of nests % in twilight No. of nests 2 c (n=23) Time of day 14% in daylight

9 Time of predation: 8 % of all nest are lost during night app. 5% of nest predated during daytime and twilight had signs from a mammalian predator => 9% of all nests were taken by an mammalian predator Fox is the most common predator at Vestamager

10 Possible mammalian predators Fox Mink Cat Dog Polecat Stoat Rat Hedgehog No. of foxes e Red fox Time of day

11 Electric fence exclosures 2 3 x 9 ha. fenced with 6-7 wires 3 x 9 ha. Control areas

12 Impact of electric fence exclosures on lapwing breeding success Procent Fenced (n=45) No Fenced (n=41) No fence (n=25) Hatched Predated Tramp/Aband. Improved hatching success Still a high predation and Still nocturnal predation!! => poor fence design

13 Impact of electric fence exclosures on lapwing breeding success - details 2 Procent Øst Fenced No fence East Hatched Predated Tramp/Aband. Procent Midt Fenced No fence Mid Hatched Predated Tramp/Aband. Procent Vest 2 Fenced West No fence Hatched Predated Tramp/Aband. East => Improved hatching success Medio => Improved hatching success West => Little or no change

14 Electric fence exclosures 22 Same 3 areas inc. Controls Improved fence design 2x Tiger Tape Grounded wire

15 Impact of electric fence exclosures on lapwing breeding success Procent 4 2 (2) (22) Fenced (n=45) Fenced (n=35) No fence (n=34) Hatched Predated Tramp/Aband. Improved hatching success as in 2 Still about 6 % lost to predators Variation between fences NONE nocturnal predation!!

16 Impact of electric fence exclosures on lapwing breeding success - details 22 Øst 22 Midt 22 Vest 22 Procent Fenced East No fence Procent Fenced Mid No fence Procent Fenced West No fence Hatched Predated Tramp/Aband. Hatched Predated Tramp/Aband. Hatched Predated Tramp/Aband. East => all predated => none nocturnal Medio => 1% hatched West => Improved hatching => none nocturnal

17 Electric fence exclosures Improve breeding success but predation still present In field season 2 still nocturnal predation In field season 22 none nocturnal predation Variation in between areas and years

18 SLUT.

20 Redeoverlevelse +/- data loggere Ingen forskel mellem andel af reder der prædateres/klækker

21 Afgræsning og vadefugleterritorier Før afgræsning Delvist afgræsset Hele reservatet afgræsset

22 Effekt af tiltag Græsning Vandstand NAO Vibe ++ Rødben ++ Klyde ++ St.Præstek r. Strandskad e

23 Prædationstidspunkt af vibereder Temperaturkurver Temperatur målinger fra en rede der prædateres Forstørrelse af samme til aflæsning af prædationstidspunkt (d. 15/5 kl. 1:49) Temperature C 5, 45, 4, 35, 3, 25, 2, 15, , 5, :49 13:49 19: :49 7:49 13:49 19:49 S/N Time (starting :49:39)

24 Prædationstidspunkt af vibereder Temperaturkurver Temperatur målinger fra en rede der prædateres Forstørrelse af samme til aflæsning af prædationstidspunkt (d. 15/5 kl. 1:49) Temperature C 5, 45, 4, 35, 3, 25, 2, 15, , 5, :49 13:49 19: :49 7:49 13:49 19:49 S/N Time (starting :49:39)

25 Prædationstidspunkt af vibereder Andre logger resultater 4, 35, 3, Temperature C 25, 2, Reden klækket 15, 1, 5, : S/N 7564 Time (starting :2:49) Erkendes ved, ungeforekomst, skalefterladenskaber og/eller kendskab til rugelængde 25, Ledning bidt af pattedyr 2, 15, Temperature C 1, 5, -5, -1, -15, : :37 14: :37 14: :37 S/N 7567 Time (starting :37:4) Kendskab til prædations-tidspunkt Ødelagt udstyr

26 Konklusion Naturpleje har gavnlig effekt på vadefugle populationer Effekten er artsspecifik Olsen & Schmidt, 23. Impact of wet grassland management and winter severity on wader breeding numbers in eastern Denmark. Basic and Applied Ecology (In press) Kragers yngleaktiviteter er følsomme over for fangstaktiviteter Især gældende ved høj bestandstæthed Olsen & Schmidt, 21. The impact of trapping and handling activities on the breeding performance of Hooded Crows Corvus corone cornix. Ringing and Migration 2 (4) Krage reagerer hurtigt og effektivt på let føde tilgængelighed Husskade reagerede ikke på samme vis men måske i stedet på antallet af krager Olsen & Schmidt, 23. The response of Hooded Crows and Magpies to exposure of artificial nests. Bird Study (In press).

27 Konklusion (fortsat) Krager er talrigt og aktivt fouragerede på vadefuglenes yngle habitater i alle døgnets lyse timer Krager synes ikke at fouragere aktivt efter vibe reder Olsen & Frandsen. Hooded crow (Corvus corone cornix) activity on wader breeding grounds in eastern Denmark (Manuscript). Viberederne prædateres hovedsageligt om natten 9% af all reder plyndres af pattedyr på Vestamager Olsen, H. Patterns of predation on lapwing Vanellus vanellus nests on a coastal meadow in eastern Denmark. (Submittet: Ardea). Ynglesucces kan forbedres ved hegning mod ræve Fortsat prædation på hegnede reder Stor variation mellem områder Olsen, H. Impact of electric fence excolsures on lapwing Vanellus vanellus breeding success (Manuscript/progress report).

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