The next instalment focuses on dietary needs and how different species have evolved beaks to suit their individual requirements. The latter come in a multitude of forms. Blue tits and goldfinches have beaks akin to tweezers, with which to extract seeds, while the hawfinch's razor-like bill can deal with a cherry-stone. However, the crossbill is the only finch that can twist its mandibles in opposite directions. Jays store acorns for winter by burying them in the ground, whereas woodpeckers can keep up to 60,000 of them in one tree trunk. Sap is also desirable, and there are a variety of methods used to obtain it. The hoatzin is the only specialised leaf-eater, and accordingly has a digestive system more akin to that of cattle. Plants recruit birds to aid pollination, and offer nectar as a reward. Hummingbirds eat little else, and the sword-bill's beak is the longest of any bird in relation to its body. Insects are also highly prized, and Galapagos finches are shown to possess some ingenuity as they not only strip bark, but also use 'tools' to reach their prey. Crows are hailed as being among the most intelligent birds, and one is shown using a twig to spear a grub within a fallen log. The robin is an opportunist, and Sir Attenborough observes one seizing morsels as he digs a patch of earth. In South America, a cattle tyrant sits atop an obliging capybara and uses its vantage point to spot passing food that may be dislodged by its grazing partner.

What if aliens landed on Earth? Much of science fiction explores the moment of first contact – what will people do when the aliens land? From H. G. Wells’ pioneering The War of the Worlds to Independence Day, Men in Black, and District 9, Invasion deals with our fears of alien invasions of earth. David Tennant explains the appeal of Doctor Who’s Daleks and Cybermen while John Carpenter and Chris Carter explore the rich appeal of the paranoia fuelled by hidden aliens with The Thing and The X-Files. It also asks, what if the monsters were our own creation? With the aid of rarely seen animation tests, Phil Tippett takes us behind the scenes in the creation of the dinosaurs of Jurassic Park. But not all invasions are hostile. Peter Coyote and Richard Dreyfuss discuss the creation of Spielberg’s spellbinding classics E.T. the Extra-Terrestrial and Close Encounters of the Third Kind. There is more than one kind of invasion.

As Michelle's loved ones cope with her sudden death, her work to unmask the Golden State Killer lives on. After inheriting Michelle's 37 boxes of case files, Paul Haynes and Billy Jensen work alongside Patton Oswalt, to finish her book.

At the heart of the film is a simple proposition: what is a good society, and what role does the widening income gap play in the deterioration of the nations's economic health? We are endeavoring for Inequality for All to be a paradigm-shifting, eye-opening experience for the public. We want to accurately show through a non-partisan perspective why extreme income inequality is such an important topic for our citizens today and for the future.

Egypt on the Brink: Arab Spring climaxed in the overthrow of President Mubarak in Egypt. But for many Egyptians, the situation has actually gotten worse. China's Ghost Towns: Fifteen years ago, China changed its policy so people could buy their own homes. Real-estate investments boomed, and new cities began popping up. The problem is: people don't live in what have become 'ghost cities.'

Prepare yourself for an unparalleled sensory experience. Samsara reunites director Ron Fricke and producer Mark Magidson, whose award-winning films Baraka and Chronos were acclaimed for combining visual and musical artistry. Samsara explores the wonders of our world from the mundane to the miraculous, looking into the unfathomable reaches of humanity's spirituality and the human experience. Neither a traditional documentary nor a travelogue, Samsara takes the form of a nonverbal, guided meditation.