There are said to be 125 different species of fish in the tidal River Thames from Teddington Lock to the Thames Estuary, and some of them end up as meals for birds and seals that live there too. Here below are a few action pictures taken during walks along Lambeth Reach.
Eel Meals
Eels found in the River Thames (Anguilla anguilla) are known as European eels. “They possibly have the longest migration of any fish species in the world.” A report on ‘Eels in the River Thames’ by the Institution of Environmental Studies goes on to explain that “the European eel begins its life in the Sargasso Sea, over 6,000 kilometres from the Thames Estuary.” Their eggs hatch into transparent, 5-8 millimetre long eel larvae called leptocephali, which float on the Gulf Stream for roughly one or two years before arriving on the shores of western Europe. As there has been a dramatic decline in their numbers during recent years, they are now a protected species.
However, being a protected species, doesn’t save them from predation. Larger fish, and as you will see here, seabirds and seals will catch and eat them if they can.
Seeing cormorants grappling with eels is quite common if you spend any time by the river but rarer is catching a seal making a meal of one.
Shell snacks
Judging by shells left on the foreshore, exposed by falling tides, birds feed on a variety of shellfish, including cockles, mussels and native oysters.
Spend any time by the river at low tide and you might well see both crows and gulls dropping shells onto a hard surface in order to crack them open. Some fly and drop their shells from a height and some attempt a sharp crack onto the ground. It doesn’t always work and juveniles having seen adults dropping shells, sometimes mistakenly drop their shells back into the water. But they learn…
The scavengers
As always, there are beaks ready to profit from what the river has to offer in the way of dead animals. Lesser black-backed gulls seem to be first in the pecking order.
It is possible that the crow got into trouble in the water and drowned before being before being attacked, though I have seen a description of such an event here: Seagulls vs a crow.
Miscellaneous meals
Yet there is other food too. Crows, ducks, geese, gulls, pigeons, and swans find alternatives in the water or on the foreshore.
Black-headed gulls appear to wait in certain spots on Lambeth Reach, treading water, catching tidbits coming in with the tide for as long as they can. If they’re carried too far upstream, they fly back to where they were, where supplies were plentiful, and the process is repeated. They can also be seen flying over the water, catching insects, particularly on warmer days.
Pigeons will eat almost anything and here, close to Lambeth Bridge, they find food on the foreshore, specially brought up on the flood tides.
Among their mainly vegetarian diet, swans will eat green algae, which is what they’re doing here, bending their long necks into the river bed at around low tide.
The above gallery is just a snapshot of bird feeding activity I’ve observed along Lambeth Reach, and to know more, you can explore the sites listed below.
Sources and further information
Article ‘Eels in the River Thames’ Institution of Environmental Studies
See: British Trust for Ornithology
The Royal Society for the Protection of Birds
The Thames Rivers Trust Community Eels Project
Swan Lifeline
The Swan Sanctuary