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The site was identified as important in 2000 because it was regularly supporting significant populations of the species listed below, meeting ('triggering') IBA criteria.

Populations meeting IBA criteria ('trigger species') at the site:

Species	Red List1	Season	Year(s)	Size	IBA criteria
Whooper Swan Cygnus cygnus	LC	non-breeding	1994	941 individuals	A4i, B1i, C2
Tundra Swan Cygnus columbianus	LC	non-breeding	1993	332 individuals	A4i, B1i, B2, C2
Brent Goose Branta bernicla	LC	non-breeding	1994	6,800 individuals	A4i, B1i, C3
Barnacle Goose Branta leucopsis	LC	non-breeding	1997	30,000 individuals	A4i, B1i, C2, C6
Common Shelduck Tadorna tadorna	LC	non-breeding	1994	6,500 individuals	A4i, B1i, C3
Northern Pintail Anas acuta	LC	non-breeding	1994	900 individuals	B1i, C3
Pied Avocet Recurvirostra avosetta	LC	breeding	1994	248-482 breeding pairs	B1i, B3, C2
Pied Avocet Recurvirostra avosetta	LC	passage	1994	1,300 individuals	A4i, B1i, C2
Eurasian Golden Plover Pluvialis apricaria	LC	passage	1994	25,000 individuals	A4i, B1i, C2
Bar-tailed Godwit Limosa lapponica	NT	passage	1994	4,600 individuals	A4i, B1i, C2
Black-tailed Godwit Limosa limosa	NT	breeding	1994	110-125 breeding pairs	B2
Red Knot Calidris canutus	NT	passage	1994	21,300 individuals	A4i, B1i, C3
Dunlin Calidris alpina	NT	passage	1994	62,000 individuals	A4i, B1i, C3
Spotted Redshank Tringa erythropus	LC	passage	1994	1,270 individuals	A4i, B1i, C3
Black Tern Chlidonias niger	LC	breeding	1994	36-41 breeding pairs	C2, C6
A4iii Species group - waterbirds	n/a	non-breeding	-	20,000-49,999 individuals	A4iii, C4
A4iii Species group - waterbirds	n/a	passage	1994	100,000-499,999 individuals	A4iii, C4

1. The current IUCN Red List category. The category at the time of the IBA criteria assessment (2000) may differ.

Ideally the conservation status of the IBA will have been checked regularly since the site was first identified in 2000. The most recent assessment (2010) is shown below.

State (condition of the trigger species' populations)
Species	Reference	Actual	Units	% remaining	Result
Greylag Goose Anser anser	6,700	6,000	individuals	90	near favourable
Grey Plover Pluvialis squatarola	3,600	2,100	individuals	59	unfavourable
Charadrius alexandrinus	23	5	individuals	22	very unfavourable
Black-tailed Godwit Limosa limosa	242	101	breeding pairs	42	unfavourable
Ruff Calidris pugnax	87	0	breeding pairs	0	very unfavourable
Dunlin Calidris alpina	9	0	breeding pairs	0	very unfavourable
Little Tern Sternula albifrons	12	1	breeding pairs	9	very unfavourable
Arctic Tern Sterna paradisaea	133	13	breeding pairs	10	very unfavourable
Short-eared Owl Asio flammeus	2	0	individuals	0	very unfavourable
Bluethroat Luscinia svecica	50	50	breeding pairs	100	favourable

Pressure (threats to the trigger species and/or their habitats)
Threat	Timing	Scope	Severity	Result
Agricultural expansion and intensification	happening now	majority/most of area/population (50-90%)	moderate to rapid deterioration	high
Other	happening now	majority/most of area/population (50-90%)	moderate to rapid deterioration	high
Invasive and other problematic species and genes	happening now	majority/most of area/population (50-90%)	moderate to rapid deterioration	high
Human intrusions and disturbance	happening now	majority/most of area/population (50-90%)	moderate to rapid deterioration	high

Response (conservation actions taken for the trigger species and/or their habitats)
Protected areas	Management plan	Other action	Result
Most of site (50-90%) covered (including the most critical parts for important bird species)	No management plan exists but the management planning process has begun	Some limited conservation initiatives are in place	low

Year	Protected Area	Designation	% overlap with IBA
1980	Kiers Gård Margrethe Kog	Fredet ved afgørelse, exl. Kirkeomgivelser	<1
1983	Vidåen; Tøndermarsken og Saltvandssøen	Special Protection Area (Birds Directive)	100
1985	Margrethe Kog	Fredet ved afgørelse, exl. Kirkeomgivelser	19
1987	Vadehavet	Ramsar Site, Wetland of International Importance	100
1988	Tøndermarsken Statsfredning	Fredet ved afgørelse, exl. Kirkeomgivelser	38
1992	Tønder Kommune	§3 beskyttet natur (alle søer, moser, vandløb, heder, enge mv)	16
1998	Vadehavet med Ribe Å; Tved Å og Varde Å vest for Varde	Site of Community Importance (Habitats Directive)	12
1998	Vidå med tilløb; Rudbøl Sø og Magisterkogen	Site of Community Importance (Habitats Directive)	5
2009	The Wadden Sea	World Heritage Site (natural or mixed)	-
2009	Vadehavet med Ribe Å, Tved Å og Varde Å vest for Varde	Marine Protected Area (OSPAR)	5
2010	Nationalpark Vadehavet	Nationalpark	-

Habitat1	Habitat detail	% of IBA
Artificial/Terrestrial		70
Marine Coastal/Supratidal		15
Marine Intertidal		15

1. IUCN Habitat classification.

Land use	% of IBA
agriculture	85
nature conservation and research	15

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Tøndermarsken, Magisterkog and Rudbøl Sø (Denmark). Downloaded from https://datazone.birdlife.org/site/factsheet/tøndermarsken-magisterkog-and-rudbøl-sø-iba-denmark on 23/11/2024.