In the first of these two articles about paintings of owls, I claimed their association with wisdom and learning was the result of their being one of the attributes of the classical goddess Athena/Minerva. As a result of that, owls often appear in portraits of those shown as being learned.

As symbols of learning and wisdom, their use is very old. In Lucas Cranach the Elder’s Portrait of Dr. Johannes Cuspinian (1502) the subject’s learning is indicated by the book which he clutches, and by the owl flying at the top right.

Closer examination, though, shows that Dr. Johannes Cuspinian’s owl isn’t as virtuous as it could be: with anthropomorphic limbs, the owl has grasped a passing swift and intends making fuller use of it later.

A sagacious owl is used by George Willison to signify the intellect of James Boswell, 1740-1795. Diarist and biographer of Dr Samuel Johnson in this portrait from 1765.

In time the owl and book(s) became something of a visual cliché, as painted by Maria Richards Oakey (Maria Oakey Dewing) in her The Philosopher’s Corner (1873).

In Pedro Américo’s A Night in the Company of the Genies of Study and Love (1883) the owls could appear for night, for study, or of course for both. Spatially it would look more likely that they were part of the night symbols, as the genie (putto) bearing the firebrand of study is on the opposite side of the goddess of night.

Very occasionally, artists explored closer relationships between humans and owls, as in Valentine Cameron Prinsep’s fascinating double portrait The Owl (before 1863).

We finally come to the greatest painter of incidental owls, Hieronymus Bosch. Not too many of his drawings have survived, but the first remarkable feature is that of those few, two have extensive owls, and a third has one very prominent owl, confirming the artist’s fascination.

The first, known as The Owl’s Nest (c 1505-1516), is a fine pen and ink study of three owls, one of which is shown inside a hole in the tree. All three birds are carefully finished in high detail, but the owl in the centre with its wings spread looks like the focus of this drawing.

Some of the peripheral details have a slightly sinister tone: a couple of less finished spiders on the right, for example. The outlined distant landscape at the lower left also seems to show an army massing, much as Bosch showed in some of his paintings, such as the Adoration of the Magi (New York). But more generally this drawing is free of menace, and is simply a superb study of those owls and the tree.

The second, known as The Wood Has Ears, The Field Has Eyes (c 1500), is in marked contrast. Its single owl stands in the hollow of a tree trunk, looking decidedly shifty, and full of malice. It’s out-numbered by other birds, which are more sketchy in appearance, but the most sinister features of this are the two ears stood in the coppice behind, and the seven human eyes laid on the grass in the foreground.

Its message is plain, and very disturbing: what you say and do will be heard and seen, even when you’re out in the countryside. It could almost be used as a poster for a modern campaign against electronic surveillance. No one knows why Bosch drew this, but it looks very much like the work of someone who is worried that their words and actions are being observed by others. It could, of course, represent paranoia. And it shows an owl as part of that sinister countryside – not an owl of false wisdom, but a spy.

The third and final drawing by Bosch is his famous The Tree-Man study for one of the most extraordinary passages in his triptych The Garden of Delights. Perched on top of one of the branches growing up from the tree-man is an owl, by comparison with the people inside the tree-man, a huge owl, as big as a man.

In the finished painting, those upper branches were largely dispensed with, and the owl doesn’t appear in that position. In the drawing, its role is unclear – as is much of the content – but it doesn’t appear to be particularly sinister or malicious; it’s just an owl.

If you were to count the owls in all his paintings, I suspect that Hieronymus Bosch was probably the most owlish major artist of all time. Starting with just one tucked away quietly in his Ecce Homo, one steps almost into the limelight of Saint Jerome at Prayer, while a hidden sibling keeps a watchful eye. By the time of his intricate triptychs, owls are coming thick and fast.

At the lower centre of his Saint Jerome at Prayer, the saint is seen at prayer, lying prone under a rock shelter. This is set in the rolling countryside near a large lake, among trees and fields.

Jerome is shown as an old man, almost bald apart from a ring of short hair around his head; he is clean-shaven, and wears a clean white habit which exposes the left side of his chest, his left leg, and arms, and his eyes are closed in concentration. Surrounding him are some of his traditional attributes: near his feet is the scarlet broad-brimmed galero (hat) of a cardinal, and there is a closed book by it. Further behind, the scarlet cassock of a cardinal is wrapped around a hollow section of tree-trunk, on which is perched an owl.

In the centre panel of Bosch’s masterpiece The Garden of Earthly Delights, another owl is perched on top of a couple towards the right edge. It’s being tempted by the offer of fruit, but doesn’t appear interested.

Like so much of Bosch’s imagery, there has been frequent speculation as to what his owls ‘mean’, and how they should be read. This isn’t helped by the seemingly multiple and contradictory meanings which have been associated with owls. Sometimes they might signify wisdom, other times ignorance; they may bring the comfort of sleep at night, or be harbingers of murder and the occult.

Each should be read in its context. There is little to indicate in other paintings that owls have any connotation or symbolic meaning beyond those shown above, nor is there evidence that Bosch used them for any generic purpose, except perhaps as a form of graphic signature.