gryllosblog   Gryllo's (aka Ian Lewis') blog. All things to do with travel, wildlife especially birds, history, architecture and anything else that interests me.

Ringing at Durlston was curtailed by an increasing wind. We had packed in by 0900 with 26 birds ringed. Highlight was undoubtedly a first year female Sparrowhawk. The female is considerably larger than a male, the largest male has a wing length some 10mm shorter than the smallest female and as I indicated in a previous post they take different ring sizes.  This sexual dimorphism is claimed to be an evolutionary adaptation allowing the pair to hunt a wider range of prey, males catching birds up to thrush size, females can predate birds as big as pigeons.

This is the fourth Sparrowhawk we have trapped at Durlston. The capture of three immatures in the last few weeks either indicates very successful breeding nearby or migration through the area.

First year female Sparrowhawk

...although direct comparison isn't possible, the smaller size and slimmer proportions of this male trapped on 26th August can be seen

Although superficially similar to Willow Warblers, the browner appearance, especially on the flanks, darker legs, shorter wings and more rounded head all identify this bird as a Chiffchaff.