When I was growing up in suburban London in the late 1950s and early 1960s, bird-nesting and egg-collecting were part of every boy’s life, an obvious extension of that other universal, tree-climbing. Now all three activities belong to a more feral past and the taking of birds’ eggs has long been illegal, which is no doubt a good thing. But I am glad to have had the intense, intimate thrill of finding a nest and handling those wonders of nature, birds’ eggs, still warm as oven-fresh bread.

Tim Birkhead’s superb The Most Perfect Thing: Inside (and Outside) a Bird’s Egg brought back that thrill and intensified the wonder I felt then. A bird’s egg is indeed, as the 19th-century American abolitionist Thomas Wentworth Higginson said, ‘the most perfect thing’. Just how perfect becomes ever more apparent in the course of Birkhead’s book, which explores every aspect of the ‘self-contained life support system’ that is an egg.

Birkhead asks all manner of questions: How are eggs made? Why are they the shapes they are? How do they get their colours and patterns? Which end of an egg is laid first? (Not the one you might assume.) But what gives his book its particular charm is that he is happy to embrace uncertainty and acknowledge that many questions have been only partially answered.

A prime example concerns the egg of the guillemot, once a great favourite of collectors (and, we learn, tasty when scrambled). Birkhead has been monitoring guillemots on Skomer Island, Wales, since 1972. Why is the guillemot’s egg so extremely pointed at the ‘little end’? The standard explanation – that the shape prevents it from rolling off the cliff ledge on which it is laid – doesn’t hold water, but is there a better one? At length, Birkhead finds a plausible, if unsavoury, explanation (the shape enables it to lodge securely in the pile of guano that is the guillemot’s nest), but, characteristically, he leaves the question open. The Most Perfect Thing is an enthralling, immensely readable book that combines deep scientific knowledge, lightly worn, with an awareness of history and a refreshing willingness to give the early pioneers of British ornithology – notably Francis Willughby and John Ray – their due. Birkhead’s other books include Bird Sense and The Wisdom of Birds.

Jennifer Ackerman’s The Genius of Birds goes one step further. In view of the evidence she marshals, the word hardly seems overstated. An American writer of popular science books, Ackerman here offers a fascinating, if rather journalistic, tour d’horizon of current research into bird intelligence and what it is telling us – which is that many birds are very smart indeed.

Take the African grey parrot Alex, who worked with the scientist Irene Pepperberg in the 1980s, mastering numbers, colours, some abstract notions and a vocabulary of hundreds of English words, which he understood and employed to talk to her. As she put him to bed on the night he died, Alex said, ‘You be good, see you tomorrow. I love you.’ No wonder scientists soon began to get the idea that there was much more to avian intelligence than they thought.

There is good evidence now that some birds are capable of insight, even ‘theory of mind’ (the ability to attribute mental states to others) and empathy. They can also perform remarkable feats of navigation, memory and recognition, and are adept at not only tool use but also ‘metatool use’ – the use of one tool on another. Even pigeons, not renowned for their mental powers, have been shown to be capable of distinguishing between Picasso and Monet, and of telling apart their works from those of stylistically similar artists.

The all-round stars of the show, however, are the phenomenally intelligent New Caledonian crows. The smartest of them all – a bird nicknamed 007 – even cracked a problem in which eight separate operations had to be performed in a particular order to win a reward of food. It took 007 just two and a half minutes to figure it out.

Other corvids are known to be highly intelligent – including ravens, whose ability to ‘count’ gets a mention in Matt Merritt’s A Sky Full of Birds: In Search of Murders, Murmurations and Britain’s Great Bird Gatherings. Most birds, as birdwatchers know, can be fooled into thinking a hide is empty if two people enter it and only one leaves. With ravens it can take up to thirty people to pile in and out before the birds lose count. But A Sky Full of Birds is not so much about the genius of birds as about the joy of watching them. Merritt is the editor of Bird Watching Magazine, and he writes about birdwatching – not that variant of trainspotting known as ‘twitching’ – with eloquent and infectious enthusiasm. This is a book that would make a birdwatcher of any open-minded reader.

A Sky Full of Birds is structured around some of the great bird spectacles to be seen on these islands, from the murmurations of starlings on the Somerset Levels to large gatherings of waders on the Norfolk coast. Yet Merritt is a great advocate of getting to know the bird life of your own little corner, however unglamorous. He writes in a fluent, self-deprecating, unostentatious style. He uses words to get it just right – ‘a barn owl bobs across the track on its own little tide of silence’ – without drawing attention to the language or himself.

If you fancy something altogether more lush, you might try James Macdonald Lockhart’s Raptor: A Journey through Birds, a hymn to English birds of prey. Philip Hoare writes on the dust jacket that Lockhart ‘puts the rapture back in the raptor. This is in-the-moment writing, raw in beak and claw.’ You might regard this as a recommendation or as a health warning, according to taste. As early as page three, we are informed that ‘at night selchies dock in the deep geos and patter ashore in their wet skins to slip amongst the dozing kye’. Really?

However, in its more relaxed moments, Raptor is full of interest. It is certainly a mine of information on William MacGillivray, a great, unjustly forgotten ornithologist whose journey on foot from Aberdeen to London in 1819, recorded in his diaries, forms a parallel narrative to Lockhart’s own raptor-seeking odyssey. And there are passages where Lockhart forgets about the birds and tells human stories with an assured touch. We learn of the burning of Lord Leverhulme’s summer house on the moors above Bolton, and of a decoy town built in the war to deflect enemy bombers.

There is just space to mention a welcome new edition of David Lack’s The Life of the Robin, a pioneering classic of scientific research that is also one of the best written of all bird books, and the most delightfully literary. The chapter on robins’ songs, for example, has four epigraphs: Keats on the autumn song, Cowper on midwinter, W H Davies on early spring, Spenser on summer. Here’s hoping that Pallas Athene, or some other enterprising publisher, reprints Lack’s other classic, Swifts in a Tower: it is high time someone did.