Thorburn's method of constructing a large finished composition relied on his field sketches which he kept in sketchbooks for constant reference. He would draw upon the vignette studies of the various birds and then place them in a carefully chosen landscape, again observed from nature. 'Referring to sketchbooks, first of the birds and then of the terrain, he would carefully yet quickly copy the selected sketches on to the picture under composition.' (J. Southern, Thorburn's Birds and Mammals, London, 1986, p. 16).
The present watercolour and the following lot are typical of the individual studies executed for this purpose and provide sensitive portraits of the birds.