I HAVE just finished exhibiting a new painting featuring a long line of tree sparrows huddled along a flowering hawthorn branch.

It took some patience to paint all 19 newly-fledged sparrows. There were 38 eyes and 114 toes to daub in.

But the time it took to apply each tiny brushstroke was nothing compared to the 20-year conservation project I undertook to boost populations of these rare birds at my home and gallery in Thixendale.

It all began when I moved to Fotherdale Farm in 1998. The garden had been levelled by a JCB digger following renovations of the farmhouse and there were barely any plants here.

Consequently the bird life was disappointing. There were just two tree sparrows living here and a few house martins nesting in the eaves.

Nevertheless I was pleased by the presence of tree sparrows, since these seemingly ordinary birds are actually an endangered species.

Populations of tree sparrows declined by 95 per cent in the UK between 1970 and 2008 and, at just 200,000 pairs, numbers are still so critically low that these birds feature on the RSPB red list of species in need of urgent conservation action.

I put up a bird feeder for them and it wasn’t long before the tree sparrows brought their first brood to the table. I watched intrigued as they showed their young how to perch on the feeders.

Tree sparrows belong to an order of birds known as passerines, derived from the Latin ‘passer’ which actually means ‘sparrow’.

Passerines include more than half of all bird species and are distinguished by the way in which their toes can move independently of one another. This makes them excellent at perching.

The youngsters quickly cottoned on to the free food supply and before long the parent birds produced a second brood. Later that summer there was a third and by autumn, I had a flock of 16 tree sparrows outside my kitchen window.

I noticed the sparrows liked to perch in a hawthorn hedge close to the bird feeder and, with an eye to composing the painting I have just exhibited, I decided to leave one branch to grow out long. It was some years before the tree sparrows obliged and I was able to take the photograph of them all balancing on the branch that I used to paint from.

At the same time as offering the sparrows food, I also put up a few nest boxes and the following spring was overjoyed to see them occupied.

I continued to add new boxes every year and the more boxes I put up the more tree sparrows I got.

Tree sparrows like to nest in colonies so I built nest box terraces for them. These consisted of a single box divided into three separate nest chambers. I even built a deluxe one with eight chambers; it was a bit like a block of flats.

It was quite funny when the first bird to move in to this one was actually a great tit! It had chosen one of the middle apartments and was horrified when a pair of noisy tree sparrows moved in next door. It would peck at any of its neighbours that dared to pop their heads through its entrance hole.

In hindsight, the block of eight was too large. The tree sparrows got confused over which nest was which and squabbles broke out when a bird entered the wrong nest. Sometimes the fights were serious and two birds would be locked in combat as they tumbled down to the ground.

One spring, a pair of mistle thrushes nested in a clump of ivy on a gate post on my driveway. I watched as they set about making their nest together, proudly flying to and fro in unison with bits of moss and long grasses in their beaks.

Then I noticed that as fast as they were bringing in their nesting materials, the tree sparrows were taking them away!

The thieving sparrows would wait for each delivery and raid it as soon as the thrushes flew off to gather more.

On their return, the thrushes looked quizzically at each other. They seemed confused as to why they were making so little progress in spite of their hard work. It was so comical.

Inevitably, the mistle thrushes returned just in time to catch a tree sparrow red-handed. They chased the bandit off, but not before the cheeky sparrow grabbed a piece of long grass in its beak.

After that the mistle thrushes kept a constant vigil. One would stand guard whilst the other brought back the necessary materials to complete the nest.

I now have 35 pairs of tree sparrows nesting here every year and by the end of each breeding season I can see flocks in their hundreds in my garden.

I often get keen bird watchers visiting my gallery and they double-take at seeing such an endangered bird in such large numbers around my feeders. And, from here these rare sparrows have spread, colonising the local area too.