Dynamic Image: Wildlife.

What is endangered?

What is most endangered? - Use well known animals or the animals that are most critically endangered, that people may not have heard of?

Links to lists here and here.

To make it more appropriate, i.e. so people can do something without having to i.e. donate money, use endangered British wildlife?
According to The Independent the then most endangered species are:

SCOTTISH WILDCAT

PONDS 
LONG-EARED OWL
BUMBLEBEES
MARSH FRITILLARY
LEATHERBACK TURTLE
SPINY SEAHORSE
ENGLISH ELM
WATER VOLE
COMMON SKATE

Including ways to help the endangered species such as... 

Making a pond in your garden.

Getting bird nest/houses in your garden.

Make a vegetation patch, or plant a nectar plant in your garden to attract insects. 

Don't throw litter in the sea.

Never buy a dried seahorse as a seaside trinket. 

Become a volunteer tree warden. 

Joining an organisation etc.