A friend of mine, an inspirational teacher, says that one of the best things parents can do is to allow children to believe that their dreams can come true. Arthur Parkinson met his first chicken as a toddler, growing up in a former mining town, and from that moment he longed for a brood of his own. So his father set to, building a handsome ark-shaped hen house, poring over Ad-Mag to find amusing poultry for sale, driving Arthur around country lanes at weekends in search of rare breeds.

Parkinson also had doting, Charlie-Bucket grandparents – Grandma Sheila, Grandad Ted and Nannar Min – who, when he was small, took him on holiday to Derbyshire, where a visit to Chatsworth led to a deep friendship with ‘Debo’ Devonshire. The ‘Queen of Chickens’, Parkinson says, was much prouder of her hens than of having lunched with Hitler, and she remained a ‘warm, interested and encouraging friend’. Dreams come true indeed.

But Parkinson’s story is not cloudless. His fourth grandparent, Grandad Cyril, died when he was three, and was bipolar. And a little way into the book he lets slip that, from childhood, he too has been ‘ambushed’ by depression. He doesn’t delve too deeply into it, but he admits that to keep the right side of darkness he needs ‘the familiar, the safe’. A vital part of this is being surrounded by his chickens – ‘my tribe’ – with their jostling energy and 30 different forms of ‘cluck’. ‘If only you could bottle up the happiness of chickens,’ he says, ‘you’d be on to a groundbreaking antidepressant.’

Not all chickens are happy, of course – even free-rangers. In a gripping chapter on ‘villains and vermin’, Parkinson describes foxes jumping seven-foot fences to grab ‘the girls’, and rats, who grow ‘bigger and bigger’, scuttling under hen houses because they relish the feeling of their backs being scratched. Cockerels fall prey to Airbnb holidaymakers who dislike being woken at dawn. And then there are battery hens, crammed into windowless sheds, tricked with light bulbs into thinking it’s always summer, so they must just keep on laying. Cheap meat and egg production has a human cost too. In several underground investigations into British chicken farms, Parkinson says, the workers used to catch and load poultry ‘have been found to be victims of modern slavery’.

But Parkinson prefers charm to alarm, and at its heart his book, stunningly illustrated with his paintings and photographs, is a celebration of chickens, and a guide to making them happy. One senses a sweet, strange soul on every page:

Chickens make me feel better and then I can be a better person, not just to my birds but to the people that matter to me too. It’s not a rule that always works, but it is an honest hope.

Across the pond, in Portland, Oregon, Tove Danovich also finds chickens a salve for depression. Every one, she says, has a distinct personality: chickens can make friends, purr, flirt, mourn. They ‘never put too many items on their to-do lists… A chicken is always happy to say no.’

Aged 13 she became aware of, and appalled by, the treatment of chickens on industrial farms, and Under the Henfluence (she is hot on poultry puns) is book-ended with grim reports from the battery front line. More chickens are killed for food every year than there are people on the planet. Scientists have dabbled with producing a meat chicken without feathers, cutting out the step between slaughter and supermarket. Broiler chickens are often lame because they’re so stuffed that their skeletons can’t support their weight. Once a hen turns two, and the egg industry is done with her, she is tossed into a metal box and pumped full of lethal quantities of carbon dioxide. Chickens’ environmental footprints may be smaller than those of beef cattle, Danovich says, but ‘the cruelty footprint is much higher’. When our descendants come to dig up our ruins thousands of years hence, broiler chicken carcasses will be markers of the Anthropocene.

But Under the Henfluence is by no means all gloom. Interweaving reflection and reportage, Danovich leads us down some bizarre byways: chickens used as therapists for young people, or nestling on the knees of ‘henshioners’ in care homes; chickens trained to perform; cities filled with wild chickens that swarm restaurants and jump on to tables to beg for food.

The biggest event of the year for chicken people is the Ohio National: two days in November, 8,400 birds. Owners bust themselves to raise the stakes. Jan Brett, grandmaster and master breeder of the American Poultry Association, dons a white crest of feathers to match her brood of bantam hens. Time for the Spinal Tap team to regroup and make Best in Show II – with chickens?