Eurasian Nuthatch

The Eurasian Nuthatch is an easy bird to recognise by its plumage and behaviour, and even more so since it is usually the only one of its kind present at a given location. Sexual dimorphism is weak and the juvenile is barely more dull than the adult. On the other hand, the general aspect can be very different depending on the subspecies, of which there are 21. We will here describe the subspecies caesia which occupies temperate Europe and to which an observer is usually confronted. The upper parts, from the beak to the tail tip, are a fairly light grey-blue, the blue standing out particularly in good light and under a blue sky, the grey dominating in the undergrowth, the bird's habitat. The wings and outer rectrices (the centre feathers are of the same colour as above the body) are of a dark grey-brown with grey-blue fringes which make the bird's plumage uniform when at rest. It is only in flight or when preening that one can see that the 3 pairs of outer rectrices have white tips. The lower parts are rufous from the throat to the abdomen, the intensity increasing from front to back. The throat and sides of the head are white. The flanks are distinctly chestnut, especially in the male. The two-coloured subcaudal feathers, white and chestnut, have a scaly aspect. A typical pirate black band runs on either side of the head, from the beak to the wing attachment passing through the lores and eyes which it encloses, then extending backwards in a curved line. The dark eye is barely visible, being included in the band. The long, pointed beak is black with the base of the lower mandible a pale grey-blue. The feet with very clawed fingers are greyish to brownish. The female has a less marked band, a paler underside, particularly the flanks, but the distinction is not easy.The juvenile resembles the female, but its headband is less defined and is shaded with brown, its plumage is more dull, and its legs are more pale. The subspecies mainly differ in size, the intensity of the grey of the upper parts and the colouration of the lower parts, which lighten following a gradient from north to south and from east to west until they become almost all white in the north and east. Therefore, in birds from the north of Japan, the chestnut is limited to the undertail coverts, and the rest of the underside is all white. Some subspecies show a slight white eyebrow.