The arrival of siskins is one of the joys of winter. This bird was one of a flock of about a dozen, feeding on alder seeds along an old railway line, now converted into a public footpath, near Willington in County Durham. 

Alder seeds are one of their main sources of food, but when the supply runs out later in winter they frequently turn up on the bird feeders in the garden, where there is a striking contrast in their behaviour. 

Siskins feeding in the wild are marvellously acrobatic, stretching, dangling, twisting this way and that to reach their reward. Never still for a second, endlessly probing with beaks that taper to a point as fine as jeweller’ tweezers, adapted for extracting the tiny, woody seeds between the cone scales.

 They are quiet, preoccupied with feeding on their own cluster of cones, so different in behaviour from the feisty siskins that feed on our garden bird table all winter. Those are mutually aggressive and constantly challenge greenfinches and tree sparrows for a perch on the feeder containing sunflower kernels. Sometimes violent conflict breaks out. They are so different in demeanour that they could almost be a different species.

 

Perhaps that’s what providing limitless luxury food in a single location does to bird behaviour: promotes competition and conflict. A siskin needs to collect about 10,000 alder seeds, half of which would be husk, to match its body weight. It must spend most of the daylight hours feeding on its natural food source but can gain the same nutritional benefit in an hour by monopolising a prime position on the sunflower seed feeder.

  

Siskins and their preferred food source are well matched, but the promise of easy street on garden bird tables reveals an aggressive nature less often seen in the wild.