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Location Australia, Western Australia
Central coordinates 121o 56.38' East  33o 47.68' South
IBA criteria A1, A4i
Area 3,952 ha
Altitude 4 - 5m
Year of IBA assessment 2009

BirdLife Australia

Summary The IBA has regularly supported more than 1% of the global population of the near threatened Hooded Plover, often more than 1% of the global population of the Musk Duck, and sometimes more than 1% of the global population of Banded Stilt. However, recent counts suggest that all species are declining and the system may not continue to meet IBA thresholds.

Site description The Lake Warden System is a hydrologically complex system of saline lakes and marshes behind beach-front dunes just inland of Esperance in Western Australia. The IBA includes six major lakes (Lake Warden, Windabout, Woody, Wheatfield, Station and Mullet Lakes) and more than 90 nearby satellite lakes depending on the water levels. The system also contains some springs, which give rise to small, shallow, brackish wetlands such as those that occur at the eastern end of the IBA. Water in the lakes ranges from moderately to highly saline, and water regimes range from almost permanent (only drying out occasionally at the end of summer) to ephemeral. The lakes are driven to varying degrees by groundwater flows and surface inflows which, when combined with the varying salinities and permanences, result in a very high diversity of wetland habitats. The lakes of the system consist of open water with or without dead trees around the periphery. There is no emergent vegetation within any of the lakes, although trees and rushes grow on the shorelines. The adjacent Pink Lake is classified as a separate IBA as it is hydrologically distinct and supports different birds.

Key Biodiversity A combined total of at least 59 species of waterbird have been recorded in Lake Warden, Woody Lake and Mullet Lake Nature Reserves. More than 30,000 waterbirds were recorded in the system from 1981 to 1985 (Jaensch et al. 1988) and total numbers probably regularly exceed 20,000 waterbirds (Department of Conservation and Land Management 2003) but only 6000 in Oct 2006 (S. Halse in litt. 2008). Fairy Tern periodically occur in small numbers at several wetlands in the system (Australian Wetlands Database 2001) with up to 30 birds observed at Lake Warden in 1982 (Jaensch et al. 1988) but none in 2003 (Clarke & Lane 2003). Australian Shelduck occured in high numbers, including 5500 birds in 1985 and 5000 birds in 1986 at Lake Warden (Department of Conservation and Land Management 2003) but this species seems to have declined subsequently e.g. 2440 in 2006 (S. Halse pers. comm. 2008). Other notable counts at Lake Warden include 3500 Black Swan in 1982 and 160 Freckled Duck, 1400 Hardhead and 1200 Hoary-headed Grebe in 2003 (Department of Conservation and Land Management 2003; Atlas of Australian Birds database). A significant count of 210 Blue-billed Duck was made at Lake Wheatfield in 2003 (Atlas of Australian Birds database). The Lake Warden system has also supported regionally significant numbers of Chestnut Teal, e.g. counts of 300 birds in 1982 and 328 birds in 1991 at Lake Warden (Jaensch et al. 1988; Department of Conservation and Land Management Waterfowl Counts in the South-west of Western Australia). The surrounding bushland supports the restricted-range Red-eared Firetail and the biome-restricted Western Rosella, Red-capped Parrot, Western Wattlebird and Western Spinebill (Atlas of Australian Birds database).

Non-bird biodiversity: Sixteen species of invertebrate have been recorded in the Lake Warden System. The Western Trout Minnow, which is listed nationally as Critically Endangered, occurs in the area (Australian Wetlands Database 2001).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Musk Duck Biziura lobata non-breeding  1981-2008  2,000 individuals  poor  A4i  Least Concern 
Banded Stilt Cladorhynchus leucocephalus non-breeding  1981-2008  10,000 individuals  poor  A4i  Least Concern 
Hooded Plover Thinornis cucullatus non-breeding  1995-1999  43-606 adults only  good  A1, A4i  Vulnerable 

IBA Monitoring

2008 high not assessed not assessed
Medium - based upon reliable but incomplete / partially representative data

Agriculture and aquaculture annual & perennial non-timber crops - agro-industry farming happening now whole area/population (>90%) slow but significant deterioration high
Human intrusions and disturbance recreational activities happening now some of area/population (10-49%) no or imperceptible deterioration low
Invasive & other problematic species, genes & diseases invasive non-native/alien species/diseases - named species happening now some of area/population (10-49%) slow but significant deterioration medium
Pollution agricultural & forestry effluents - nutrient loads happening now majority/most of area/population (50-90%) slow but significant deterioration high

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Lake Warden Nature Reserve 699 protected area overlaps with site 588  
Mullet Lake Nature Reserve 1,917 protected area overlaps with site 559  
Un-named (No. 32259) Nature Reserve 7 protected area overlaps with site 2  
Woody Lake Nature Reserve 613 protected area overlaps with site 302  


IUCN habitat Habitat detail Extent (% of site)
Wetlands (inland) Ephemeral; Saline lakes; Salt marshes  major

Land ownership The IBA overlaps with four nature reserves managed by the Department of Environment and Conservation but also includes private land e.g. north of Mullet Lake.

Land use

Land-use Extent (% of site)
nature conservation and research major
rangeland/pastureland minor
Notes: Water ski-ing and sailing are popular activities at Woody Lake and Windabout Lake, respectively.

Protection status The IBA overlaps four gazetted Nature Reverses - see separate section for details. There is also an overlap of 159 ha with the Esperance Protected Area which is being gazetted.

Acknowledgements Stuart Halse kindly commented on the nomination and provided data.

References Clarke, A.G. and Lane, J.A.K. (2003) A waterbird census of selected wetlands along the coastal margins of Esperance District, Feb-Mar 2003. Unpublished report: WA Dept of CALM.

DEWHA (2008) Directory of Important Wetlands in Australia. Lake Warden System - WA027. Downloaded from on 15 November 2007.

Department of Conservation and Land Management (1999) Esperance Lakes Nature Reserves Management Plan 1999-2009. Department of Conservation and Land Management and National Parks and Nature Conservation Authority: Perth.

Department of Conservation and Land Management (2003) Information Sheet on Ramsar Wetlands (RIS) for Lake Warden System Western Australia. Department of Conservation and Land Management: Busselton.

Jaensch, R.P., Vervest, R.M. and Hewish, M.J. (1988) Waterbirds in Nature Reserves of South-western Australia, 1981-1985: Reserve Accounts. RAOU Report 30. Royal Australasian Ornithologists Union: Melbourne.

Platt, J., Nicholas, B., Short, R. and Gee, S. (1996) Esperance Region Catchment Planning Strategy. Agriculture Western Australia: Perth.

Singer, M. (1999) Hooded Plover report no. 2. 1996-199. Supplement to Western Australia Bird Notes no. 90.

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Lake Warden System. Downloaded from on 29/10/2016

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