I often collect bird pellets and take them back to my art studio to dissect. These matted clumps of indigestible fur and bone are coughed up by birds every day and offer fascinating insights into their diets.

Made up of anything a bird cannot digest, including fur, feathers, bones, and even seed husks, pellets are spat out daily by many species, although most people have only heard of owl pellets.

It’s amazing what they contain. I have come across leveret bones and frog skulls in barn owl pellets and the remains of a goat and the wing bones of a gull in a white-tailed eagle pellet. The gull’s bones were alarmingly sharp – I would not want these stuck in my throat!

I once made a display box of the contents of just one barn owl pellet. It included four vole skulls, three common shrew skulls, their fur, and bones.

And a few years ago, my daughter took some barn owl pellets to school and her class found a weasel skull inside one of the pellets.

At first, they, incorrectly, identified it as a fox skull, which made me chuckle. But they were delighted when they discovered that it really was a rare find.

You can find pellets inside or close to nests, as well as beneath the trees, rocks, or fence posts where a bird has perched. If you are going to try dissecting one, I recommend using tweezers and soaking them in water first.

Although they look like rolls of poo, unlike faeces, pellets have not been digested and so they do not have a smell nor do they carry disease.

They do have a 'fusty' scent, but that is all. And little owl pellets are almost pretty because the wing cases of the beetles they eat make them shimmer.

Bird pellets actually have an important function inside bird nests. Owls, kestrels and even kingfishers, for instance, break up their pellets to line the floor of their nests with.

Kingfisher pellets are one of my favourite pellets to examine. Roughly the size of a large peanut, they are made up of individual tiny fish scales and fine fish bones and are exceptionally fragile and fine.

Kingfishers nest in tunnels dug deep into riverbanks and these underground chambers are inherently damp. There is also nowhere for faeces of the developing chicks to drain to and so the pellets help to absorb all the wet and smelly poo.

In fact, a female kingfisher will not lay her eggs until she has built up a soft layer of pellets for them to rest on.

As soon as one of the other kingfishers in the nest, say the male or a chick, coughs up a pellet, the female quickly and deftly shreds it with her long sharp beak. Interestingly, it seems it is only the female that does this.

Pellets also play a key role in supporting wider eco-systems. For example, as the detritus of owl pellets builds up in an owl nest it will attract flies, which in turn attracts spiders for smaller birds to eat.

Of particular interest is the white shouldered clothes moth, which, attracted by the indigested fur of voles, lays up to 200 eggs at a time on the pellet of a bird of prey.

The larvae that develop then eat the animal fur and feather inside the pellet. While many of these larvae will reach maturity, others become a life-saving food source for hungry birds over winter.

I often see tree creepers and wrens digging out larvae from the floor of my owl and kestrel boxes. They also eek out pupae from the crevices on the sides of the boxes, which I made from natural tree stumps.

It’s amazing to witness the circle of life provided by bird pellets. Who would think that these ugly clumps of regurgitated bones and fur could hold such treasure?

Robert’s gallery in Thixendale is now open. To visit, you can either book a free private viewing for yourself or your support bubble, mornings only, or simply drop in from 1pm-5pm. www.robertefuller.com