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The River Thames: Wildlife Species
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Introduction and General Information

The River Thames winds all the way through London, through 17 London Boroughs, and out into the Thames Estuary. The Tidal Thames includes all of the River Thames downstream from Teddington Lock. Within the Tidal Thames different areas are considered to be freshwater (upstream of Lambeth), brackish (between Lambeth and the confluence with the River Darent) and marine (further seaward).

The River Thames is an important water feature through London. While the majority of the sites of particular importance for birds are outside Greater London, the river, its tributaries, and adjacent waters and wetlands within Greater London do provide important habitats for birds, and are also used by certain mammals, reptiles and amphibians. 

  • "River Thames and Tidal Tributaries Site of Metropolitan Importance SMI - The River Thames supports a diverse mix of habitats, including open water, intertidal mud, sand, shingle and small areas of relatively poor saltmarsh. The SMI is particularly important for a range of bird and fish species, including Common Tern (Sterna hirundo), Reed Warbler (Acrocephalus scirpaceus) [Acrocephalus scirpaceus - Eurasian reed-warbler], Grey Heron (Ardea cinerea) [Ardea cinerea - Grey heron] and Teal (Anas crecca) [Anas crecca - Common teal], and Bass (Dicentrarchus labrax), Eel (Anguilla anguilla) and Flounder (Platichthys flesus)." (D225)

The Thames is particularly important in severe winters and cold spells, because it provides an area of ice-free water for wintering water birds. (J322.53.w1)

It is important to have information about the distribution and abundance of species likely to be affected, including information about the location of birds, seasonal variations in species and numbers, and data on rare and endangered species for which extra protection may be required. (D10)

  • In addition to up-to-date information from data banks, surveys should be carried out within hours of a spill notification, to determine the number of birds present in the area threatened by oil, and if possible to estimate the percentage of birds already oiled, using indicator species such as gulls. (D10)

The Thames may be described in several different sections, including the stretch in Inner London, the Inner Thames from Tower Bridge downstream to Tilbury, and the Thames Estuary. For the purposes of the Wetland Bird Survey, the Thames Estuary "is usually taken to include the coast between the Rivers Medway and Crouch and upstream to Barking in east London." (D227)

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Bird Species on and near the Thames in Inner London

A variety of species were recorded along the River Thames in Inner London, specifically between the Waterloo and Blackfriars Bridges during the period January 1979 to December 1981 and between Lambeth and Westminster Bridges during 1968-1985. (J322.50.w1)

This study shows clearly the variety of birds which may be found in the Inner London area of the Thames.


The following water birds are found on the Thames in Inner London in winter: (J322.62.w1)
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Bird Species on and near the Thames in Greater London

The Inner Thames, the portion of the Thames Estuary from Tower Bridge downstream to Tilbury, is used by birds as a migratory route and (both water and mud) as a feeding site. Use of different areas for feeding varies with the tide as well as over the years with the foods available. For example, as the Thames has become cleaner, the number and size of fish, as well as invertebrates, has increased, but tubifex worms have decreased, therefore the river is more suitable for some species than it used to be, but less attractive to others. (J322.56.w1)

The following bird species have been recorded on or within 10 metres of the Thames in Greater London during a variety of surveys, as collated by Greenspace Information for Greater London (GIGL): (D207)

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Waterfowl and Waders of the Thames Estuary 

"An estuary can be defined as 'a partially enclosed area at least partly composed of soft tidal shores, open to saline water from the sea, and receiving freshwater from rivers, land run-off or seepage". (D227)

It is recognised that it is difficult to decide exactly where an estuary, which is a transitional habitat, starts and ends. For the purposes of the Wetland Bird Survey, the Thames Estuary "is usually taken to include the coast between the Rivers Medway and Crouch and upstream to Barking in east London." (D227)

The Thames Estuary is one of the five most important sites in the UK for wintering water birds.

Internationally important numbers are found of: (B45)


Nationally important numbers are found of: (B45)


The WeBS low-tide counts, acknowledged as not being complete since not all parts of the Thames Estuary were included in the counts, showed high densities of water birds on the shore north of Coalhouse Fort (off East Tilbury Marshes), Higham Creek, Hadleigh Ray, Southend Flats and on the south shore, Egypt Bay eastwards. Additionally, high densities were seen in the inner areas of the Estuary. (D227)

On the Inner Thames - the portion of the Thames Estuary from Tower Bridge downstream to Tilbury, waterfowl, gulls, waders and terns may be found. The extensive mudflats in the Tilbury area (at the edge of the London Area) are important for waders and ducks, while freshwater outflows where various rivers join the Thames (e.g. the Darent, Beam, Ingrebourne, Lea and Roding, as well as sewage outfalls such as that at Barking/Creekmouth, are attractive feeding areas for waterfowl, gulls and terns. (J341.80.w1)

As an example of the species which may be found in saline lagoons, at Cliffe Pools, thousands of wading birds (shorebirds) use the pools at high tide in winter, many species use the area on passage, and breeding water birds in summer include Recurvirostra avosetta - Pied avocet, Tringa totanus - Common redshank, Vanellus vanellus - Northern lapwing, Charadrius hiaticula - Common ringed plover, Podiceps cristatus - Great crested grebe, Tadorna tadorna - Common shelduck, and Egretta garzetta - Little egret. (W84.Nov05.w1)

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Water Bird Species in the London Area

The following water bird species (waterfowl, shorebirds and other waders, gulls, terns, grebes, divers etc.) are seen within "the London Area" covered by the London Natural History Society, as residents, winter visitors, and/or passage migrants [not including some very rare species with only a few individuals ever recorded]: 

Loons & grebes:


  • Fulmarus glacialus - Northern fulmar "rare visitor" with 30 records for London to 2000. (J322.65.w1)
  • Hydrobates pelagicus - European storm-petrel "rare visitor, normally storm driven". In 2000, individual birds were seen at Rainham Marsh, Dartford Marsh, Stone Marsh and the River Thames (possibly the same one or two birds in the sightings at different locations). (J322.65.w1)
  • Oceanodroma leucorhoa - Leach's storm-petrel a "rare visitor, often during 'wreck' conditions." In 2000, individuals seen on Dartford Marsh, Rainham Marsh (flying upriver), and two reservoirs. (J322.65.w1)
  • Morus bassanus - Gannet (Species) a scarce visitor, with 60 records to 2000. (J322.65.w1)
  • Phalacrocorax carbo - Cormorant a breeding resident, for example at Walthamstow reservoirs and Broadwater Lake. Counts of over 200 birds are regular at Walthamstow, Queen Mary, Staines, Wraysbury, Queen Elizabeth II and Walton reservoirs, and is also seen in Inner London, for example seen at 14 sites during 2000, with 30 birds visible on the Thames at Lambeth Bridge in early March. (J322.65.w1)
  • Phalacrocorax aristotelis - European shag "irregular visitor, occasionally in good numbers. Usually occurs in winter, but may stay for long periods." Peak sightings are usually in mid-December. In 2000, individuals seen on several reservoirs, also on the Thames at Wandsworth Park, and in Inner London, in Regent's Park. (J322.65.w1)

Herons etc.

  • Botaurus stellaris - Great bittern "scarce winter visitor that has become more regular in recent years, often returning to favoured sites." Individuals have wintered in the Lea Valley since the early 1980s. (J322.65.w1)
  • Egretta garzetta - Little egret. a "scarce but increasing visitor." This species is now a breeding bird in Essex. Birds may be seen e.g. at various reservoirs, Dartford Marsh, also in Inner London, with one seen over Regent's Park in August 2000. (J322.65.w1)
  • Ardea cinerea - Grey heron common resident breeding species, with more than 400 nests in 2000, including more than 20 nests at each of Battersea Park and Regents Park in the Inner London area. (J322.65.w1)


  • Cygnus olor - Mute swan a common resident breeding species, with more than 100 known nests including some in Inner London; groups of several dozen may be seen on the Thames. (J322.65.w1)
  • Anser albifrons - Greater white-fronted goose "scarce winter visitor and passage migrant in variable numbers." (J322.65.w1)
  • Anser anser - Greylag goose (Species) "Common feral breeding resident" with nearly 300 birds at Sevenoaks wildfowl reserve in 2000; one hundred or more may be seen in some Inner London locations such as Kensington Gardens. (J322.65.w1)
  • Branta canadensis - Canada goose a "very common breeding resident" with hundreds of birds at some sites including more than 100 at some sites in Inner London. (J322.65.w1)
  • Branta bernicla - Brent goose "formerly scarce migrant and winter visitor, greatly increased in recent years." Seen at various reservoirs, Rainham Marsh, The Wetland Centre at Barnes (WWT) and other sites. (J322.65.w1)
  • Alopochen aegyptiacus - Egyptian Goose "increasing feral breeding resident." (J322.65.w1)
  • Tadorna tadorna - Common shelduck "decreasing breeding resident on Lower Thames, regular visitor to major inland waters where it breeds in small numbers." (J322.65.w1)
  • Aix galericulata - Mandarin duck "established, locally common, feral breeding resident." Widespread in most of this area except for Kent; small numbers seen in Inner London. (J322.65.w1)
  • Anas penelope - Eurasian wigeon "common winter visitor, with occasional summer records." There may be 2,000 or more individuals in this area during the winter months of December and January, but few in Inner London (e.g. in 2000, a single record at Lambeth Bridge in October). (J322.65.w1)
  • Anas strepera - Gadwall "local breeding resident and common winter visitor." In 2000, there were about 2,500 birds present in January and about 1,300 in December. Sites on which tens to hundreds of birds were seen included Rainham Marsh, The Wetland Centre (WWT) at Barnes, various reservoirs etc. In Inner London, smaller numbers are seen (e.g. two birds at Regent's Park in March, up to five during the summer in Buckingham Palace and two pairs breeding). (J322.65.w1)
  • Anas crecca - Common teal "common winter visitor and rare breeder." Several hundred in winter at sites such as Beddington sewage farm and the Thames Barrier; more than 100 on the Thames in the Barnes/Putney area in February 2000. In Inner London, one seen at Regents Park in September 2000. (J322.65.w1)
  • Anas platyrhynchos - Mallard "very common and widespread breeding resident, with numbers increasing in winter." Includes 200 or more on the River Thames at more than one location (Barnes, Putney). In Inner London, found at several sites, with more than 150 at Surrey Docks in February and St James's Park in September, 2000 and small numbers breeding. (J322.65.w1)
  • Anas acuta - Northern pintail "passage migrant and winter visitor in small numbers, very occasional summer records, declining." (J322.65.w1)
  • Anas querquedula - Garganey "scarce passage migrant, rare in winter, very occasional breeder." (J322.65.w1)
  • Anas clypeata - Northern shoveler "common passage migrant and winter visitor, scarce breeder, with birds often recorded in summer." In 2000, breeding recorded at Rainham Marsh, Rye Meads and Brent Reservoir; tens to a hundred or a few hundred birds at various reservoirs, Rainham Marsh, etc. In Inner London, small numbers but as many as 18 at Regent's Park in January 2000 and 48 in Hyde Park/Kensington Gardens. (J322.65.w1)
  • Netta rufina - Red-crested pochard "rare autumn and winter visitor, with its true status clouded by frequent escapes." Individuals seen on various lakes, gravel pits, the River Thames at Hammersmith, The Wetland Centre (WWT) at Barnes, etc. (J322.65.w1)
  • Aythya ferina - Common pochard "common winter visitor and migrant, scarce breeder." A few dozen breeding pairs in 2000, including several nesting in Inner London. Up to 200 or more birds at some sites in winter, such as Walthamstow Reservoir, Broadwater Lake and Wraysbury gravel pit. (J322.65.w1)
  • Aythya marila - Greater scaup "regular but uncommon winter visitor and passage migrant, occasional large influxes during cold weather. Most records in 2000 were of single birds at a variety of sites. In Inner London, one individual was seen at Surrey Docks. (J322.65.w1)
  • Somateria mollissima - Common eider "scarce visitor, usually in winter." Individual once present may remain for some time (1.5 years is not unprecedented. (J322.65.w1)
  • Clangula hyemalis - Long-tailed duck a "scarce but annual visitor" with three females, one at each of three locations, recorded during 2000. (J322.65.w1)
  • Melanitta nigra - Black scoter "passage migrant and occasionally winter visitor, never numerous." Seen e.g. Barking Bay/Marsh, Rainham Marsh, Staines Reservoir, Hilfield Park Reservoir, Queen Mother Reservoir, Queen Elizabeth II Reservoir etc. in 2000. (J322.65.w1)
  • Bucephala clangula - Common goldeneye "common winter visitor, occasional summer records." Peak counts at some locations number tens to more than 100 (e.g. Staines Reservoir in 2000). (J322.65.w1)
  • Mergellus albellus - Smew "winter visitor in highly variable numbers." In 2000, up to 166 individuals from 30 sites were reported in January, with the last birds leaving in march and the first winter arrivals in November. (J322.65.w1)
  • Mergus serrator - Red-breasted merganser "scarce winter visitor and passage migrant." In 2000, about 29 individuals seen, at sites such as Dartford Marsh, and various reservoirs, also in Inner London one bird on The Serpentine in Hyde Park one day in December. (J322.65.w1)
  • Mergus merganser - Common merganser "regular winter visitor, very rare in summer." In 2000, seen at 63 sites, with a few tens of birds on some reservoirs in January to march, and December. (J322.65.w1)
  • Oxyura jamaicensis - Ruddy duck "widespread winter visitor of feral origin, localised breeder." At least 12 pairs bred in 2000. The locations with the most birds were Hilfield Park Reservoir (more than 300 during the winter, Broadwater Lake (more than 100) and Staines Reservoir (more than 100); in Inner London occasional birds were seen in St. James's Park. (J322.65.w1)


Gulls, terns etc.

  • Stercorarius parasiticus - Parasitic jaeger "regular, but scarce, autumn migrant; rare in spring and summer." Seen as singles or small groups, at sites along the Thames (e.g. one flying upriver at Dartford Marsh) as well as various reservoirs. (J322.65.w1)
  • Larus melanocephalus - Mediterranean gull "regular winter visitor and passage migrant." May be a dozen or so individuals across this area in a given winter month, at a wide range of sites. (J322.65.w1)
  • Larus minutus - Little gull regular passage migrant, seen also occasionally in both summer and winter. Mainly on various reservoirs, also seen at Dartford Marsh and Swanscombe Marsh. (J322.65.w1)
  • Larus ridibundas - Common black-headed gull common both as a winter visitor and a passage migrant. Occasionally breeds here, with a colony at Staines Reservoir. Reaches numbers of e.g. 10,000 at Rainham Marsh, and "vast hordes" roost on the Thames at night during the winter. (J322.65.w1)
  • Larus canus - Mew gull common as both a winter visitor and a passage migrant. More than 1,000 individuals may be found at a time e.g. on Rainham Marsh in winter. (J322.65.w1)
  • Larus fuscus - Lesser black-backed gull a common visitor, most regularly seen in autumn and winter. Also increasingly breeding in London. (J322.65.w1)
  • Larus argentatus - Herring gull common, particularly in winter; may be hundreds or even a few thousand at one site. Small numbers breed in London. (J322.65.w1)
  • Larus cachinnans - Yellow-legged gull (Larus michahellis) "regular migrant and winter visitor, commonest in the autumn, especially along the Thames." Seen on various reservoirs, also e.g. Rainham Marsh, Dartford Marsh, Swanscomb Marsh. (J322.65.w1)
  • Larus marinus - Great black backed gull fairly common as a winter visitor, in small numbers (has reached e.g. 100 or more at Rainham Marsh), including individuals in Inner London, e.g. on the Thames at Millbank; at other times of year rarer. (J322.65.w1)
  • Rissa tridactyla - Black-legged kittiwake "regular, but scarce, passage migrant and winter visitor." Usually only a few birds at any one time, although in 1999 about 1,000 moved through the London area in February. (J322.65.w1)
  • Sterna sandvicensis - Sandwich tern "uncommon passage migrant, often in flocks." Seen e.g. Dartford Marsh, various reservoirs. Has been seen in Inner London e.g. two individuals at Waterloo Bridge in August 2000. (J322.65.w1)
  • Sterna hirundo - Common tern "common summer visitor and passage migrant, increasing as a breeding species." Has been seen in Inner London, e.g. at Canada Water, SE16 in 2000. Breeds at some sites such as Island Barn Reservoir, Brent Reservoir and Staines Reservoir. On passage usually seen first along the Thames in east London, and is seen e.g. Dartford Marsh and Barking Marsh (sometimes more than 100 at these sites). (J322.65.w1)
  • Sterna paradisaea - Arctic tern "regular spring and autumn passage migrant, occasionally in large flocks." Generally sighted on various reservoirs, also e.g. Dartford Marsh, Swanscombe Marsh, one flying upriver at Wandsworth, five at Hampstead Heath, as many as four at East India Dock Basin etc. (J322.65.w1)
  • Sterna albifrons - Little tern "uncommon, but annual, passage migrant." Mainly various reservoirs, also Dartford Marsh and a flock of 15 at East India Dock Basin. (J322.65.w1)
  • Chlidonias niger - Black tern "regular, often common, spring and autumn passage migrant, occasional in summer." Total numbers seen vary from about 70 to two or three hundred over a spring or autumn passage season; groups may be of as many as 40 or more on occasion. Sightings often occur along the Thames, but may also involve inland waters away from the Thames. (J322.65.w1)
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Mammal Species on, in and near the Thames 

Mammal species which are most likely to be badly affected by oiling are those which live in or near water and which rely on their fur to provide insulation. (P14.4.w4) These include species such as otters (Lutra lutra - European otter) and water voles (Arvicola terrestris - Water vole).

Note: Other mammal species can also get oiled on occasion, but not necessarily due to oil spills:

  • Bats may become oiled by flying into oil left in places such as garages. (B284.9.w9, V.w47)
  • Hedgehogs may become oiled by falling into containers of oil left open in garages or workshops. (B259.w10, V.w47)

Terrestrial and semi-aquatic mammals:

Notable species of terrestrial and semi-aquatic mammals recorded within 10 metres of the Thames River in Greater London during a variety of surveys, as collated by Greenspace Information for Greater London (GIGL) include: (D207)


A further indication of species which may be found in wetland areas in Greater London is given by the following species have been recorded within The Wetland Centre at Barnes: (B383.w4)

Marine Mammals:

Of marine mammals, the following are recorded as "frequent visitors" to the tidal Thames; individual animals have been sighted at a variety of locations but there is not yet sufficient data to confirm any patterns of trends in their use of the river: (D170)

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Reptiles & Amphibians in and near the Thames

Notable species of reptiles and amphibians recorded within 10 metres of the Thames River in Greater London during a variety of surveys, as collated by Greenspace Information for Greater London (GIGL) include: (D207)

A further indication of species which may be found in wetland areas near the Thames in Greater London is given by the following species have been recorded within The Wetland Centre (WWT) at Barnes: (B383.w5)

At Rainham Marshes, great crested newts (Triturus cristatus - Northern crested newt) and Triturus vulgaris - Smooth newt have been found, as have Natrix natrix - Grass snake and common lizards (Lacerta vivipara - Viviparous lizard). (V.w75)

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Organisations with further information

The following organisations may be able to provide further information on species of wild animals in London:
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Authors & Referees

Author Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referees Dr Virginia Pierce (V.w73); Alison Giacomelli (V.w75); Louise Wells (V.w71)

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