Kingfishers dwell on the tributaries and backwaters of the Thames. However, many species utilise the mighty river itself, and for good reason. The Thames now supports more than 125 species of fish. A bird found in high numbers on the Thames is the Cormorant. Diving down tens of metres and utilising an elastic throat, these pursuit fishing birds can catch and eat some huge fish, including eel and Flounder. Cormorants can be regularly seen swimming past the Houses of Parliament and are one of the birds most at home in the centre of the city.