Anyone who feeds birds in their garden will have noticed that the number of customers they receive varies considerably from month to month, as well as year to year. Sometimes you will be filling up the feeders twice a day while at other times once a week will suffice. Many people worry that if there is little demand for the peanuts or sunflowers they provide, then the local population of tits or finches is at a low ebb.
This is often not the case. In a good autumn, when there is a heavy crop of nuts, berries and seeds, there is little reason for many woodland species to wander into gardens in search of a free meal. In contrast, in years when there is a shortage of natural food available, considerable numbers of birds will come to garden feeders.
Declining stocks of food during the winter will also make a difference to the numbers and variety of birds that visit your garden. Siskins, for example, rarely visit gardens until they have exhausted the supply of seeds on alders, their favourite winter food. This usually happens in mid-January, so by the end of January you are likely to start seeing these attractive little birds on your feeders. They will continue to visit until early April. They then migrate back to the coniferous forests where they breed.
So if your feeders are quiet this winter it may not be because numbers have fallen but be due to an abundance of food in the countryside. Similarly, an abundance of birds in your garden may not indicate a large and healthy population: the birds may have been forced there due to a shortage of food elsewhere.