It’s tough for birds when their foraging supplies run out. They’ve gobbled up every holly and hawthorn berry or seed they can lay their beaks on and most insects are safely hibernating. Without our help, gardens would offer meagre pickings, perhaps enough for one or two residents and a flock of passing migrants, like fieldfares or redwings. But studies have shown that between 20 and 30 blue tits can flit in and out of a garden if there's a bird feeder, even if you only see four at a time.

The upside for the providers of food is a far more interesting garden. The British Trust for Ornithology’s (BTO) garden bird feeding study showed that, due to food provision, 16 species went to the average garden in the 1970s. But regular food supply increased the tally to 23 species by 2010.

I’m always thrilled to look out the window and witness a vibrant throng round the feeders. I’m also acutely aware of how all these tiny creatures rely on me. Robins, especially the cock birds, establish winter feeding territories that can include our generous supplements. Without this, the rest of the territory might not be able to support a single bird.

Many birds, such as yellowhammers and siskins, start visiting gardens in winter. Although they ordinarily spend most of their time in the countryside, food supplies run short by winter, especially if there’s been a shortage of cones in the forest or the ground is covered with snow. During lean times, these birds can nip into a nearby garden, rather than having to search far and wide for vital rations.

Don’t imagine things get any easier in the spring. Just as we have the dreaded hungry gap, when winter veg is finished and this year’s produce is still in seed trays, birds are equally challenged. When the breeding season is upon them, there are no seeds or berries and tidy gardeners don’t even have the decency to lay on weed seeds.

Cock birds are busily establishing and defending their territories and hens are starting to lay eggs. They need more food when hardly any is available. During a warm spell, insects come out of hibernation and make a vital food source for adults and chicks. But when it’s cold and wet this resource isn't available.

Bird feeders play an important role by keeping the adults going and letting them feed their chicks with any insects they find. Even seed-eating species, such as chaffinches and house sparrows, feed highly nutritious insects to their young, while the adults need our contributions.

As the chicks fledge, the adults use bird feeders as an important educational resource. Young chaffinches are taken to a bird table, where the parent starts eating some seed. The teenagers are ignored even if they sway beguilingly from side to side begging a crumb, so they’re forced to learn to fend for themselves at the restaurant.

Greater spotted woodpeckers play the same game with suet treats. They park their fledgling on a nearby branch, take a fragment of suet from the feeder and place it close to the youngster. It’s then taken to the branch with the feeder where it watches its parent feed and then fly away. The wean has to learn the trick or starve.

This bird feeding is all very well, but are we feeding birds junk food, the equivalent of fish and chips or a ready meal? Surely they should be eating healthy beetle larvae and caterpillars? Always assuming they can get them, of course.

The answer is both yes and no. One BTO study showed that greater spotted woodpecker pairs raised more chicks if they had access to suet-based food the previous winter. On the other hand, two studies on tits showed they had fewer chicks. That said, the general case for feeding is overwhelming, especially if you buy good quality products.