My latest ornithological interest is catching and ringing Treecreepers. I do this in the hope of gaining an understanding of their population dynamics, survival and dispersal. The research is conducted with the appropriate licences under the Wildlife and Countryside Acts.
In the wild, Treecreepers Certhia familiaris are rather unassuming little birds, easily slotted into category of "LBJ" (Little Brown Job). They are common in British woodlands as they creep up the trunk of a tree in a rather mouse-like fashion. As a bird approaches the crown of the tree, it flies back down and starts up again, often spiralling around the trunk. This behaviour readily distinguishes them from the other tree creeping bird, the Nuthatch, which can creep up and down the trunk with equal facility. The Treecreeper's long decurved bill is adapted to probing the deepest crevices of bark in order to winkle out insects that may be lurking there. Its tail feathers are quite rigid, and these act as a prop when resting against the side of a tree trunk.
The inconspicuous Treecreeper looking for insect prey in the crevices of bark Treecreepers are easily caught by attracting them to sound recordings of their song. The song is a thin Willow Warbler-like whistle, easily missed amongst the clamour of louder bird song. However a male Treecreeper can pick out the song from some distance and will fly to "see off" a perceived intruder. In this way it can be intercepted by a mist net.
A Treecreeper enmeshed in a mist net. A licence is required to undertake this research In the hand the Treecreeper seems transformed from a rather drab image to a medley of browns, buffs and creams, a really exquisite little bird.
A ringed Treecreeper showing the subtleties of its plumage colouration
Wing extended revealing an array of spots and barring on the flight feathers and coverts.
This research study is still in its infancy. As the sample size of ringed birds increases it will be possible to discover more about the natural history of these fascinating little birds.