Small tortoiseshell
The pretty small tortoiseshell is a familiar garden visitor that can be seen feeding on flowers all year-round during warm spells. Overwintering adults may find resting spots in sheds, garages or even houses.
Small white
The small white is a common garden visitor. It is smaller than the similar large white, and has less black on its wingtips.
Small-leaved lime
A scarce tree of central and southern England, in particular, the Small-leaved Lime can be found in ancient woodland. It is has sweet-smelling flowers in summer and nut-like fruits in autumn.
Small-spotted catshark
Small-spotted catsharks used to be called lesser-spotted dogfish - which might be what you know them best as. It's the same shark, just a different name!
Smew
This small duck is an uncommon winter visitor to the UK, where they're usually found on lakes, reservoirs and gravel pits.
Smooth newt
You are likely to spot the smooth newt in your garden or local pond. It breeds in water in summer and spends the rest of the year in grassland and woodland, hibernating over winter.
Snake's-head fritillary
The nodding, pink-and-purple-chequered flowers of the snake's-head fritillary are said to resemble a snake, hence the name. Declining with the loss of our meadows, this delicate plant can be seen in spring.
Snakelocks anemone
It's easy to see where the snakelocks anemone got its name when you spot its flowing tentacles. But be careful when out rockpooling, those tentacles give a nasty sting!
Snipe
Listen out for the 'drumming' sound of a male snipe as it performs its aerial courtship display. It's not a call, but actually its tail feathers beating in the wind. Snipe live on wet grassland, marshes and moorlands throughout the UK.
Snow bunting
Only a few pairs of snow bunting breed here, so look out for this striking black-and-white bird in winter around Scotland, the North West and the East coast of England.
Snowdrop
Perhaps the first sign that spring is just around the corner is the snowdrop poking its way through the frosted soil of a woodland, churchyard or garden. From January, look for its famous nodding, white flowers.
Soft brome
Soft brome is a tall, annual grass of roadside verges, waste ground and meadows, and is a 'weed' of arable land. It has long, grey-green leaves and loosely clustered flower spikes.