Saturday, December 31, 2022

Pill millipedes

 

I found these beautiful little pill millipedes Glomeris marginata, with their overlapping plates of armour, under the loose bark of a fallen tree in Weardale. When disturbed, they curl up into a ball, like an armadillo, and then roll away.  They are easily confused with the superficially similar pillbug aka pill woodlouse Armadillidium vulgare, which has similar armour and ability to roll-up, but has only 7 pairs of walking legs (click here for pill woodlouse post









Friday, December 23, 2022

 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.

Monday, December 19, 2022

Dung beetle heaven

At the end of November, during that wonderfully mild spell of late autumn weather, we found this large dung beetle Geotrupes stercorarius crossing a country lane in Teesdale. Ordinarily, it might have spent the winter in the pupal state underground but I suspect that the warm conditions might have hastened its development. Now it was probably looking for somewhere to dig a tunnel and hibernate, so we moved it to a place of safety - a field with horses, where it could burrow down under a pile of dung: dung beetle heaven


More on dung beetles, which I have most often found in spring, here