I was just 8 years old, going to get the milk from the front porch. I happened to look out of the window and saw something that excited me, so I called my mother, pointed -- and yelled: "Look, Mum! Tits!"

Whack! Not even looking where I was pointing, she slapped me.

"Ow! What did you do that for?" I said. "Look!"

There were two little birds on the milk bottle. Pretty little things they were, smaller than sparrows, with white cheeks and cobalt-blue crowns, wings and tails. They were blue tits, two of them, prizing up the little round cardboard tab in the middle of the bottle top so they could pull it off and get at the creamy, yellow milk that had risen to the top.

Even at 8, I knew more about birds than my mother did -- and it wasn't my fault what those ones were called.

On a frosty British winter morning there was nothing like a bowl of hot oatmeal porridge with some sugar and the cream of the milk on it. In those days, milk was delivered to the front door every morning in glass bottles. One particularly harsh winter, there were newspaper stories about widespread incidents of bottles being opened and the rich, creamy, top of the milk going missing. As I had already discovered for myself, the culprits were birds: tits.

As it happens, blue tits especially have the habit of tearing bark off trees to get at insects. And so it was that, because of these enterprising, fat-loving little birds, the British milk industry had to change the way its bottles were capped.

As I write this, I am sitting in my study on a January morning with two stoves going. While I was having my morning tea with honey, I was watching tits, as there are several species common to the woodlands and gardens of Japan. It's been really cold, with lots of snow. Last night, the pipes froze in the house even though the heating was supposedly working. A few days ago we had a spate of avalanches here in Nagano Prefecture, some that buried not only snowboarders, but also cars. The snow is about a meter deep outside our house, and three or four times that farther up the mountain. Winter can be tough here.

Flocking to the fat

That is one of the reasons why we hang out little meshed baskets of fat for the small birds. Ours is best-quality fat, either from our own pigs, or from wild boar. In winter, when it's really cold or windy, or when the trees are encrusted with snow, small birds flock to our fat meshes hung from branches 3 to 4 meters above the ground, with a 50 cm piece of branch dangling below on a string.

This arrangement is stable enough for small and agile birds to alight on, but wobbles and swings wildly if a starling, jay or crow tries to take the goodies. Once in a while a Japanese green woodpecker will have a go, but soon gives up. However, great tits, long-tailed tits, willow tits, varied tits, nuthatches and Japanese pygmy woodpeckers are regulars, and share their find of fat with no problems at all. These are all extremely attractive little birds and a delight to watch through the window.

I know there is a debate about the practice of feeding wild birds, with some saying it is wrong to encourage them to rely on food set out by humans. My mum and grandma would not have understood that at all, because they always fed the birds in winter. However, I can see the sense of it when I hear of birds starving because the human providers were away for a while and the food they relied on wasn't there. But because our baskets of fat last up to three weeks, there's never any break in its availability throughout winter.

We also notice that on warm days, when small insects emerge from cracks in the bark on the surrounding trees, the little birds don't bother with the fat. In other words, they only use the fat to tide them over the harsher times.

I forward the same argument for providing nest-pots and nest-boxes for these little birds who normally rely on large, old trees with holes and hollows in them. However, so much old woodland has been destroyed or replaced -- including in our Afan Woodland Trust, where no trees are more than 60 years old -- that it will be at least another century before they can provide nesting places for tits, owls and bats.

If we widen the argument to other creatures, then, of course, I am entirely against feeding bears, wild boars or monkeys. As they say in Canada and parts of the United States, "a fed bear is a dead bear." In other words, if a bear becomes accustomed to getting food from humans it can become dangerous, because it will no longer be fearful or wary of humans. Then the bear has to be shot.

In Japan, monkeys that have become accustomed to taking food handed out by humans have become a terrible nuisance, even going in through car windows to snatch bags of food from the terrified passengers. Monkeys are small, but very strong, and they have extremely nasty bites.

One of the jobs I had as a park warden in Ethiopia was to shoot baboons that were raiding fields and terrorizing locals.

I am still not wholly decided about feeding deer. I know of cases, during times when the snow was so thick that they couldn't forage, that some were able to survive because people spread out hay for them. It seems a humane thing to do.

Killing with kindness

However, I have seen small islands in the north whose edible plants and grasses have been grazed to the ground, leaving only those plants that are inedible or even toxic. Then the deer will strip the bark from the trees, killing them. In some parts of Hokkaido, 80 percent of the deciduous trees have been killed in this way. This eventually leads to mass starvation of the deer and a serious degradation in the diversity and quality of the forest. All this, in some cases, because animals that would have died have been kept alive through human kindness -- leading to overpopulation in relation to an area's food supplies.

So, in the case of deer and wild boar, where there are no animal predators to control the numbers, I firmly believe that humans should cull them and use them sensibly to maintain balance. Personally, I far prefer venison and wild boar to meat from domesticated animals, because as far as I'm concerned it's tastier and safer.

As for our own pigs, they have a half-hectare meadow and some woods to run around and snuffle about in, with their own spring water and a pond for drinking and wallowing. We also feed them with a variety of pesticide-free produce from our own fields. They are the healthiest pigs you will ever see -- and it is their fat that the little birds love to peck at.