Hooge Platen Nature Reserve Bird island in a shipping channel

November 13th-17th, Minsmere, SuffolkRene Beijersbergen

Westerscheld estuary

Keeping an eye on the island

Volunteers at work

Little Tern breeding in the “safe haven”…

Behind the “seawall”……..

The beach, the seawall and the dunes

Vegetation of annuals

Waterdunen on the estuary

Terns breeding on artificial sites

Pionieers Hooge Platen

0

100

200

300

1978 1984 1990 1996 2002 2008 2012

bre

edin

g p

airs

(n

)

Little tern Avocet Kentish plover

1982

1986

1990

1994

1998

2002

2008

2012

0

4000

8000

Population development of of gulls and terns

Common tern Sandwich tern Blackheaded gull Mediterrenean gull

Breeding pairs and success of Sandwich tern

0

2000

4000

6000

1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 20110

0,4

0,8

1,2

broedparen (n) broedsucces (juv/paar)

Little tern Common tern Sanwich tern0

25

50

75

100

sandeel herring

Prey items fed to the chicks (left) and partners on the breeding site in three species of terns in the same period.

Terns feed mainly on two species of fish

• Bottomdweller• Poor swimmer• Local• Year round

• Live in shallow water (-20 m)

• Young and adult share partly same feeding ares

H e r r i n g

• From surface to bottom• Fast swimmer• Migrator• Young and subadults near

coast from may-august• Spawning area and nursery

geographical separated• Adults live from the Channel till the Norwegian coast

S a n d e e l

Years of poor reproduction by lack of food:

• Bodyweight of chicks does not increase over days

• Chicks die of starvation• Both parents go out

fishing• Increase of predation

So what can we conclude…..

• Feeding sites are getting more and more unpredictable when the function as a nursery for sandeel and herring is becoming less

• Breeding sites (Waterdunen & Zwin) are better off on close distance of nurseries and other spots where small fish aggregrates

• Terns are dependant on small fish for the young chicks and bigger fish for themselves

• The days when producing a clutch and the first days after hatching seems to be the most vulnerable days.