Wherever you walk along the Thames Path there should be plenty of wildlife to observe and enjoy although, of course, the time of year you are there is important. There will be birds present all year round, but if you're keen on wild flowers then April to September is the time to visit, and if insects are an interest of yours choose June to September.
Plants of the riverside seem to be especially colourful from the bright yellow of the flag iris and marsh marigold in spring to the pinks of the willowherbs and purple loosestrife during summer. Plants of particular note along the Path are the nationally rare Loddon lily and snake's-head fritillary, both flowering on a few flood meadows in early spring.
Insects are in abundance during the summer when dragonflies and damselflies, amongst the largest and so most noticeable, are active. There are various species, many wonderfully coloured and you'll be able to watch them mating, laying eggs, hunting for food or patrolling their territories.
Of the mammals you'll no doubt see rabbits and maybe a stoat or a weasel. Unfortunately you're unlikely to see a relative of the latter, an otter, although thankfully they are returning to the upper reaches of the Thames and perhaps in the future will be more plentiful and obvious. Another animal in trouble is the water vole, 'Ratty' of Kenneth Grahame's 'Wind in the Willows'. They used to be very common on the Thames emerging from their holes in the bank and busily ploughing backwards and forwards across the river, but their numbers have crashed in recent years. Let us know if and where you spot one.
The most obvious animals are the birds, many of which being water birds are large and thankfully don't fly away as soon as you appear! The majestic mute swan has to be the symbol of the Thames and is increasingly common thanks to the ban in the 1980s on anglers using lead weights. Swans eating these weights in mistake for the grit they need to take in to break down plant material in their gizzards were poisoned and killed and their numbers diminished considerably.
Ducks and Geese
Wherever you go you'll see the commonest of Britain's ducks, the mallard, which like all ducks is especially resplendent from October to March. But other species of ducks visit the river too, so look out for tufted duck, pochard and wigeon. Geese, larger relatives of ducks, also abound in places, usually found in large noisy flocks grazing in fields near the river or roosting on the water itself. The Canada goose is very common.
Another privilege is the glimpse of a flash of blue and orange as a kingfisher darts across the river.
Coots with the white flash on their heads, and moorhens with a red flash, are also everywhere, both giving the impression of being very important and busy birds. In contrast, the common but beautiful great crested grebe is serene, and the chance of seeing its elaborate courtship display during the spring is a privilege. Another privilege is the glimpse of a flash of blue and orange as a kingfisher darts across the river. Do keep your eyes open for them, they are more frequent than you might imagine. Finally, of the larger birds, the heron can be missed until it flies. It is capable of standing completely still for ages waiting for a fish or frog to appear, but when it takes off its large flapping flight is unmistakable.
Throughout the summer swallows, house martins and the less common sand martin can be seen hunting insects over the water. At this time of year, too, reedbeds and scrub next to the river are the haunt of several species of warbler who spend their winters in Africa.