Survival - free for iPhone and Android

Race against the clock in a battle for Survival! Tap, drag,
scroll, swipe and pinch your way through a series of wild
mini-games to earn the title of Top Survivor. Packed full of
ARKive's photos of endangered animals, this fun-packed game tests
your speed, agility, endurance and intelligence.
Bugs Count - free for iPhone and Android

An interactive guide to UK bugs, with interesting facts, ID tips
and photos from the Natural History Museum. You can also help
scientists with valuable research into our changing environment by
looking for the six Species Quest bugs.
Project Noah - free for iPhone and Android

Can you complete Project Noah's field missions? Missions can
range from photographing squirrels or mushrooms to tracking
migrating birds or invasive species. Missions can contribute to
ongoing research projects, or just be for fun. Project Noah also
lets you see what plants and animals have been spotted near you and
learn more about them. If you need help identifying a plant or
animal you've seen, take a picture and upload it to Project Noah.
Project Noah's community will ID it for you!
National Geographic - various for iPhone

National Geographic have loads of fantastic nature and wildlife
apps, ranging from jigsaws to spot the difference games.
Bees - free for iPhone

Buzz around flower fields collecting pollen for your beehive.
Along the way, look for bonuses and presents while avoiding the
energy-zapping dragonflies. In the beehive, make organic honey and
collect jars to store it in. You can play as the queen bee, a
worker or a drone to keep your hive alive.
Chirp! Bird Songs Europe + - £1.99 for iPhone

Learning bird songs can be hard, but not with Chirp! Simply tap
the bird photo to flip it over and reveal helpful tips plus a short
description of the song. After listening, try the quiz to test your
memory. Answer fast to earn a score multiplier and get on the high
score table! You can also get a version for USA birds.