Think sprite or hobgoblin and you are nearly there when it comes to the Aye-Aye, surely one of the weirdest looking creatures on earth? With its large saucer-like eyes, massive ears, and long skeletal middle finger which its uses to tap for grubs on logs, this lemur both fascinates and terrifies us. Endemic to the forests of Madagascar, some local people believe that if one looks at you, someone in your village will die. They even hang up an aye-aye on the edge of the village in some areas to ward off evil spirits. We are responsible for the demise of the aye-aye in other ways; by destroying the forests on which it depends. But as we hear, get up close to an aye-aye and you’ll meet one of the most alluring and watchable mammals on the planet. Not merely a creature in close harmony with its disappearing world, but as Brett Westwood and Verity Sharp discover an ambassador for conservation which still has us in its thrall.

The relationship between humans and pigeons is one of the oldest on the planet. They have been our co-workers; delivering messages, assisting during the war, providing a source of food, a sport and obsession for many, and a suitable religious sacrifice. They helped Darwin with his theory of Natural Selection, have become a powerful symbol of peace and helped us unravel some of the mysteries of navigation. Yet many of us still regard them as vermin, as “rats with wings”. Brett Westwood and Verity Sharp probe into this paradox, and explore how pigeons have helped us and what they can reveal about the homing instinct and what it means for us to feel at home

For a plant that we generally associate with shady, damp places, a plant that has no flowers or scent, the Fern has drawn us into her fronds and driven an obsession that is quite like any other. Pteridomania or Fern Madness swept through Victorian Britain in part thanks to the availability of plate glass from which manufacturers could build glass cases for growing ferns. The trade in ferns all but wiped out some species from parts of the UK and fern hawkers sold specimens on street corners in London. Brett Westwood and Verity Sharp trace our relationship with the fern on a journey from a slide of spores in Durham, to the art of Nature Printing via a garden fernery and discover that the fern is still weaving its magic spell over us.

Poppies are associated with many things but to most people they are a symbol of remembrance or associated with the opium trade. Natural Histories examines our fascination with the flower. Lia Leendertz visits the Royal Botanic Gardens Kew where James Wearn shows her a collection of poppy paraphernalia from around the world. Andrew Lack, of Oxford Brookes University and author of Poppy, explains how the flower made its way to the British Isles with the introduction of agriculture, and Joe Crawford of Exeter University describes the popularity of the opium poppy in 19th century Britain, especially among female poets. A vibrant opium trade led British horticulturalists to try and establish a home grown opium crop - without success. Fiona Stafford appraises the poppy in art encouraging us to look again at Monet's late 19th century painting of a poppy field in northern France. It was painted just a few decades before the outbreak of the Great War which established the red poppy as a permanent reminder of the bloodshed of fallen soldiers.

How did we get from the gorgeous red junglefowl scratching away in the jungles of south-east Asia to the chicken now eaten in its millions? Brett Westwood and Joanna Pinnock trace the trail. The story's told by Greger Larson, Director of the Palaeogenomics & Bio-Archaeology Research Network; Annie Potts, Director, New Zealand Centre for Human-Animal Studies; Dr Joanne Edgar, University of Bristol School of Veterinary Sciences and by a visit to meet real red junglefowl, the original chicken, at the Pheasantry at Sudeley Castle in Gloucestershire.

Bees have been the subject of fascination and reverence since ancient times. Natural Histories explores the story of bees and why humans like to compare themselves to them, seeing ourselves as either virtuous workers or moral examples. The ancient Greek poets thought of themselves as bees who foraged and chose the sweetest words to produce great art, while the Victorians admired bees for their industry and selflessness. But with news of declining bee populations around the world, Natural Histories talks to those who monitor the decline of some species and try to address the ecological problems causing their demise, as well as to honeybee keepers who say that in the cities, bees are actually thriving.

The dreamy smile of the sloth has made it wildly popular, but once its slowness was condemned and saw it named after one of the seven deadly sins. Brett Westwood and Joanna Pinnock talk to those who really know, understand and live with sloths and ask if we're still projecting our own feelings onto them. Our changing attitudes to sloths tell us more about ourselves than about this harmless animal. Dr Rebecca Cliffe, founder of the Sloth Conservation Foundation and a leading researcher, is in the rainforest in Costa Rica with them right now. She describes how local people feel about them, while she sits under a tree with a sloth at the top. Joanna Pinnock tries for her own encounter with Marilyn the sloth and her baby Elio at ZSL London Zoo, and experiences the magic of sloths at first hand. William Hartston, author of Sloths: A Celebration of the World’s Most Misunderstood Mammal. explains the vexed history of sloth first as a sin then its next incarnation as a harmless South American treetop dweller named after that sin, and the repercussions for the animal down the centuries. He also shares his opinion on the best sloth in film. And it's not Sid from Ice Age. And the poet Debbie Lim reads her poem Gift of the Sloth, describing other ways in which they deserve our admiration, but again not for the reasons that the current popular image of sloths would seem to suggest.

In the final episode, Becky Ripley and Emily Knight search for pufflings that have run into trouble on their journey from their burrows to the sea, guided by the light of the moon.

The season is ending. Becky Ripley and Emily Knight go in search of the last pufflings left in the burrows on the Isle of May to give them a quick check-up before the birds leave their family homes and head out to sea.

How do you draw puffins to an island they abandoned long ago? Emily Knight and Rebecca Ripley are on Ramsey Island off the west coast of Wales. Here they're trying a very loud solution - blasting out the sound of puffins, from boom bass speakers.