Spurred into action by the spring sunshine, our resident carrion crows have one thing on their minds. Just as they’ve done for the past five years, this pair have begun to build on the foundations of last year’s nest, high in the crown of a statuesque oak – the tallest tree in their territory.

Unlike rooks and jackdaws, which are social species and tend to nest in colonies, carrion crows are fairly solitary birds. Reaching sexual maturity at about three years of age, they form socially monogamous but genetically promiscuous pairings. This means that, while they typically mate for life, extra-pair copulation between a female and a male other than her pair-bonded mate is not unusual.

The nest is about 15 metres up, near the top of the canopy, close to the trunk and wedged securely between two thick forked limbs. From afar it looks like a platform of jumbled sticks, but through my spotting scope I can see that it is in fact cup-shaped.

Once the tree is in leaf, the nest will be concealed from sight, but for now it is in full view of predators and, though they have yet to lay, the crows are actively defending their territory, mobbing the local buzzards as they circle overhead, and seeing off passing sparrowhawks and kestrels. For another measure of protection, they have constructed a decoy nest in a neighbouring tree, conspicuously sited on an outer branch.

‘Once the tree is in leaf, the nest will be concealed from sight, but for now it is in full view of predators.’ Photograph: Ian Redding/Alamy

The male and female have been working together to construct their high-rise abode, taking it in turns to alight on my silver birch and break off twigs. Whippy and full of sap, these don’t snap cleanly. One bird vigorously bends them back and forth, almost toppling over with the effort. The other takes a different approach, twisting a twig to weaken the wood fibres, then tugging it free.

These charismatic corvids are often considered to be bad omens. However, as with magpies, in some cultures it is not the mere sighting of a crow but the number of birds that is significant – two crows are lucky, three bring health and four wealth. During this tumultuous time, the presence of this pair of black-feathered beauties is certainly bringing me joy.

• The first picture on this article was changed on 3 April 2020 because an earlier image was of jackdaws, not carrion crows.