Thomsons Lake is a lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 nature reserve

Nature reserve

A nature reserve is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research...

 in the City of Cockburn, Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

, approximately 25 km south of the central business district

Central business district

A central business district is the commercial and often geographic heart of a city. In North America this part of a city is commonly referred to as "downtown" or "city center"...

 of Perth

Perth, Western Australia

Perth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....

, the state capital, and on the southern fringes of the Perth metropolitan area. It in the suburb of Beeliar

Beeliar, Western Australia

Beeliar is a suburb of Perth, Western Australia, located within the City of Cockburn. The name refers to the Beeliar people, a tribe of Indigenous Australians who had land usage rights over the southern half of Perth's metropolitan area. The suburb contains the Thomsons Lake Nature Reserve....

, 7 km south-west of Jandakot Airport

Jandakot Airport

Jandakot Airport is an Australian general aviation airport located in Jandakot, Western Australia. Jandakot airport opened in 1963. From 1 July 1998, Jandakot Airport Holdings purchased a 50-year lease with a 49-year option to operate and maintain the airport including its conservation...

. It is a still largely natural wetland, with adjoining native vegetation, surrounded by land developed for housing and agriculture, that regularly supports large numbers of shorebirds

Wader

Waders, called shorebirds in North America , are members of the order Charadriiformes, excluding the more marine web-footed seabird groups. The latter are the skuas , gulls , terns , skimmers , and auks...

 and other waterbirds.

Protection

The lake is listed on the Register of the National Estate

Register of the National Estate

The Register of the National Estate is a listing of natural and cultural heritage places in Australia. The listing was initially compiled between 1976 and 2003 by the Australian Heritage Commission. The register is now maintained by the Australian Heritage Council...

. With the similar Forrestdale Lake

Forrestdale Lake

Forrestdale Lake is a lake nature reserve in the City of Armadale, Western Australia, approximately 25 km south of the central business district of Perth, the state capital, and on the southern fringes of the Perth metropolitan area. It lies immediately south of the suburb of Forrestdale, and 8 km...

 10 km to the east, it forms the Forrestdale and Thomsons Lakes Ramsar Site

Forrestdale and Thomsons Lakes Ramsar Site

The Forrestdale and Thomsons Lakes Ramsar Site comprises two separate nature reserves, totaling 754 ha in area, protecting two shallow fresh to brackish, seasonal lakes in a suburban and agricultural landscape in south-western Western Australia. It is used mainly for birdwatching and walking. It...

, designated under the Ramsar Convention

Ramsar Convention

The Ramsar Convention is an international treaty for the conservation and sustainable utilization of wetlands, i.e., to stem the progressive encroachment on and loss of wetlands now and in the future, recognizing the fundamental ecological functions of wetlands and their economic, cultural,...

 on 7 June 1990 and recognising it as a wetland of international importance. The lake and its surrounds are registered as Nature Reserve 15556, vested in the Conservation Commission of Western Australia and managed by the Department of Conservation and Land Management. The reserve is also part of the Beeliar Regional Park.

Description

Thomsons Lake Nature Reserve, including the lake and adjacent woodland, has an area of 538 ha. The lake is a shallow, brackish, seasonal lake with a large area of open water when full. It has extensive fringing sedgeland typical of the Swan Coastal Plain

Swan Coastal Plain

The Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geological and biological zone, one of Western Australia's...

, and is a major breeding site, migration stop-over and semi-permanent drought refuge

Drought refuge

A drought refuge is a site that provides permanent fresh water or moist conditions for plants and animals, acting as a refuge habitat when surrounding areas are affected by drought and allowing ecosystems and core species populations to survive until the drought breaks...

 area for waterbirds. It usually dries out during the summer, though occasionally retaining some water through the year. It is fenced to exclude feral predators. It is mainly used for birdwatching, nature walks, and general recreation by surrounding residents. Within the reserve there is a network of fire-breaks

Firebreak

A firebreak is a gap in vegetation or other combustible material that acts as a barrier to slow or stop the progress of a bushfire or wildfire. A firebreak may occur naturally where there is a lack of vegetation or "fuel", such as a river, lake or canyon...

 and management access tracks used for bushwalking, while horse riding

Pleasure riding

Pleasure riding is a form of equestrianism that encompasses many forms of recreational riding for personal enjoyment, absent elements of competition. Pleasure riding is called "hacking" in British English, and in parts of the eastern United States and Canada...

 is only allowed on a perimeter track outside the vermin-proof fence.

Geology and hydrology

The lake occupies a depression between two dune systems – the Bassendean System to the east, and the younger Spearwood System to the west. These dunes are the result of the accumulation and subsequent distribution of beach sands along successive shorelines from a series of marine incursions combined with the prevailing westerly winds. Palaeobotanical

Paleobotany

Paleobotany, also spelled as palaeobotany , is the branch of paleontology or paleobiology dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments , and both the evolutionary history of plants, with a...

 studies show that the lake sediments are 30-40,000 years old, making them the oldest found in Western Australia. The lake lies on the Jandakot Groundwater Mound

Jandakot Mound

The Jandakot Mound, or Jandakot Groundwater Mound, is an unconfined aquifer in south-western Western Australia. It is the smaller of the two main shallow aquifers near Perth that together supply about 40% of Perth's drinking water. Its highest point lies about 18 km south of Perth’s central...

 - a region of elevated groundwater beneath the Swan Coastal Plain.

Flora and fauna

Water milfoil

Myriophyllum

Myriophyllum is a genus of about 69 species of freshwater aquatic plants, with a cosmopolitan distribution. The center of diversity for Myriophyllum is Australia with 43 recognized species...

 grows abundantly in the lake. The fringing zone around the edge is characterised by the introduced

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

 bulrush

Typha

Typha is a genus of about eleven species of monocotyledonous flowering plants in the family Typhaceae. The genus has a largely Northern Hemisphere distribution, but is essentially cosmopolitan, being found in a variety of wetland habitats...

 Typha orientalis and the sedge

Cyperaceae

Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...

 Baumea articulata. When water levels drop, the club-rush Bolboschoenus caldwellii becomes established on the exposed mudflat

Mudflat

Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of...

s within the fringing zone, while behind it is a belt of Baumea juncea and Baumea articulata with emergent Native Broom and shrubs of Orange Wattle

Acacia saligna

Acacia saligna, commonly known by various names including coojong, golden wreath wattle, orange wattle, blue-leafed wattle, Western Australian golden wattle, and, in Africa, Port Jackson willow, is a small tree in the family Fabaceae...

. Behind these is a belt of the trees Flooded Gum

Eucalyptus rudis

Eucalyptus rudis, Flooded gum, is a medium sized tree with rough, dark and light grey bark, however north of Perth its bark is smooth and very similar to Eucalyptus camaldulensis. Leaves are stalked, alternate, ovate to orbicular 12 x 7 cm, slightly discolourous and dull grey-green...

 and Stout Paperbark

Melaleuca preissiana

Melaleuca preissiana, commonly known as Stout Paperbark, Modong or Moonah, is a tree that grows in coastal areas of southwest Australia. It grows up to 15 metres tall, occurring chiefly in areas that are seasonally wet. It has papery bark, and pointed leaves from 1 to 1½ centimetres long and 1 to 2...

, and the shrub Grey Stinkwood

Jacksonia furcellata

Jacksonia furcellata, commonly known as Grey Stinkwood, is a species of leafless broom-like shrub or small tree that occurs in the south west of Western Australia. One of the most common plants of the Swan Coastal Plain, it is an excellent colonizer of newly cleared land. It is often seen growing...

. On higher ground these are replaced by open forest or woodland dominated by Jarrah, Firewood Banksia

Banksia menziesii

Banksia menziesii, commonly known as firewood banksia, is a species of flowering plant in the genus Banksia. It is a gnarled tree up to 10 m tall, or a lower spreading 1–3 m shrub in the more northern parts of its range. The serrated leaves are dull green with new growth a paler grey...

 and Candlestick Banksia

Banksia attenuata

Banksia attenuata, commonly known as the candlestick banksia or slender banksia, is a species of plant in the proteaceae family. Commonly a tree, it reaches 10 m high, but is often a shrub in dryer areas 0.4 to 2 m high...

. Some 476 vascular plant

Vascular plant

Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...

s (including 133 introduced weeds) from 81 families

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 have been recorded in the reserve.

The lake is one of the last refuges for the endangered Australasian Bittern

Australasian Bittern

The Australasian Bittern , also known as the Brown Bittern, is found in south-western and south-eastern Australia, Tasmania, New Zealand, New Caledonia and Ouvea. Populations in Australia and New Zealand have declined in the 20th century.It is a large bittern, patterned and streaked brown, buff...

 on the Swan Coastal Plain; it is the only wetland in the Perth metropolitan area where the Marsh Harrier

Marsh harrier

The marsh harriers are birds of prey of the harrier subfamily. They are medium-sized raptors and the largest and broadest-winged harriers. Most of them are associated with marshland and dense reedbeds...

 still breeds, and one of few known breeding sites for Baillon's Crake

Baillon's Crake

The Baillon's Crake is a very small waterbird of the family Rallidae.-Distribution:Their breeding habitat is sedge beds in Europe, mainly in the east, and across Asia. They used to breed in Great Britain up to the mid-19th century, but the western European population declined through drainage....

. It regularly supports more than 1% of the national population of four shorebirds: Red-capped Plover

Red-capped Plover

The Red-capped Plover , also known as the Red-capped Dotterel, is a small plover. It breeds in Australia. The species is closely related to the Kentish Plover, Javan Plover and White-fronted Plover.-Description:Red-capped Plovers have white underparts and forehead...

 (with up to 1,000 counted), Black-winged Stilt (3,000), Red-necked Avocet (3,000), and Curlew Sandpiper

Curlew Sandpiper

The Curlew Sandpiper is a small wader that breeds on the tundra of Arctic Siberia. It is strongly migratory, wintering mainly in Africa, but also in south and southeast Asia and in Australasia...

 (2,500). The lake often holds more than 10,000 waterbirds, with the highest number counted over 20,000. The most numerous are Australian Shelduck

Australian Shelduck

The Australian Shelduck, Tadorna tadornoides, is a shelduck, a group of large goose-like birds which are part of the bird family Anatidae, which also includes the swans, geese and ducks. The Anatidae article should be referred to for an overview of this group of birds.This is a bird which breeds...

 (with up to 1,600 counted), Pacific Black Duck

Pacific Black Duck

The Pacific Black Duck is a dabbling duck found in much of Indonesia, New Guinea, Australia, New Zealand, and many islands in the southwestern Pacific, reaching to the Caroline Islands in the north and French Polynesia in the east. It is usually called the Grey Duck in New Zealand...

 (4,500), Grey Teal

Grey Teal

The Grey Teal, Anas gracilis is a dabbling duck found in open wetlands in New Guinea, Australia, New Zealand, Vanuatu and Solomon Islands....

 (6,000), Australasian Shoveler

Australasian Shoveler

The Australasian Shoveler is a species of dabbling duck in the genus Anas. It ranges from 46–53 cm. It lives in heavily vegetated swamps. In Australia it is protected under the National Parks and Wildlife Act, 1974...

 (2,000), and Eurasian Coot

Eurasian Coot

The Eurasian Coot, Fulica atra, also known as Coot, is a member of the rail and crake bird family, the Rallidae. The Australian subspecies is known as the Australian Coot.-Distribution:...

 (7,000). The reserve contains a population of Western Grey Kangaroo

Western Grey Kangaroo

The Western Grey Kangaroo is a large and very common kangaroo or macropod, found across almost the entire southern part of Australia, from just south of Shark Bay to coastal South Australia, western Victoria, and the entire Murray-Darling Basin in New South Wales and Queensland...

s. The Long-necked Tortoise

Narrow-breasted Snake-necked Turtle

The narrow-breasted snake-necked turtle or long necked tortoise is a species of turtle in the Chelidae family.It is endemic to the southwestern part of Western Australia....

 is present. Six frog

Frog

Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...

 species and up to 80 aquatic invertebrate

Invertebrate

An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

taxa have been recorded.