Owl Awareness Day: The Tawny Owl
- Debbie Jordan
- Aug 4
- 4 min read
The 4th August is Owl Awareness Day. To mark this, and the 350th anniversary of the publication of Francis Willughby’s Ornithologia, this post will focus on part of the descriptions of the Tawny Owl in Ornithologia.
Ornithologia had two entries and multiple names for the Tawny Owl, which is known today by the official binomial name of Strix aluco. The first entry was called the Common Brown Owl, Ivy Owl, Screech Owl or Strix. The second was called the Grey Owl or Strix cinerea. Both of these refer to the Tawny Owl, but the first refers to the brown morph variant of the species and the second to the grey morph variant.
Today, it is known that both colour morphs occur in Europe. The brown morph is predominant in the humid climate of western and southern Europe, whilst the grey morph is predominant in the east and north. In the coldest northernmost areas of Europe, the variant is almost exclusively the grey morph. It is also known that the colour variant is genetically determined. Furthermore, the variant causes changes beyond colour, with the grey morph also having increased size, energy management, reproductive success and immune resistance.
In Britain today, the brown morph overwhelmingly dominates as a result of numerous virtually snow-free winters. Without the snowy winters, the grey morph becomes highly visible to predators because it loses its camouflage advantage. However, in Willughby’s time, it was very different. Ornithologia was written shortly after the peak of the Little Ice Age and the climate was considerably colder with very harsh winters and prolonged snow cover, which would have provided little camouflage for the brown morph. As a result, in his time, the grey and brown morphs were both commonly sighted in England.
In his observations on the brown morph variant, Willughby described that it appeared bigger than it was, weighed 12½ ounces (354.3g), had a wingspan of 2 feet 9 inches (83.8cm) and was 14 inches (35.5cm) in length from the tip of the beak to the end of the tail.
The bill was a horn-light bluish colour and the mouth was wide. Beyond the nostrils and below the eyes grew bristly feathers that had black shafts. It had huge protuberant eyes and the borders of the eyelids were broad with red edges. Willughby commented that “the eyes in this bird are nearer to the ears than in any other animal I know.” He also noted that the ear holes were three times greater than the Barn Owl and covered with valves (today known as operculum). A circle of feathers encompassed the eyes and chin. It consisted of a double row of feathers: the exterior more rigid and variegated white, black and red; the interior consisting of soft feathers and was white mingled with a flame colour. The middle part of the head outside of the circle was dark brown.
The back and upper side of the body were particoloured ferruginous and dark brown-blackish. Willughby commented that if each single feather was “curiously observed,” they were found to be waved with alternating cinereous and brown transverse lines. The belly and lower side of the body were the same colour as the back but more dilute with some white. The bottoms of all feathers were black. The feet were feathered almost down to the claws with a thick dirty-white plumage, sprinkled with small dark specks or waved dark lines, leaving only two or three of the annular scales bare.
The number of flight feathers in each wing was 24. The exterior webs of the outermost terminated in slender points like bristles and stood like teeth of a fine comb. The wings were very much shorter than the end of the tail. The covert feathers of the wings, primarily those around the middle, and the long scapular feathers, were spotted with white especially on their interior vanes. The wing and tail feathers were marked with six or seven cross bars of a dirty white colour, tinted sometimes ferruginous and sometimes brown. The tail had 12 feathers and was 6½ inches long (16.5cm). The middlemost feathers were the longest, the rest in degrees shorter, and all ended in a sharp point.
The sole of the foot was callous and a horn-blackish colour. As in all Owls, the outermost of the fore toes turned backward. However, the middle toe did not have a serrated inner edge, unlike the Barn Owl.
In the grey morph variant entry, Willughby stated that it was very like the aforementioned but distinguished by several aspects, which suggested to him that they were of a specific difference. The main differences were: that this was grey, that the other was brown; that this had long dark spots on the breast, which the other lacked; that the interior circle in this was only particoloured dusky and white.
Specifically, he wrote that the stiffer feathers of the circle were particoloured white and blackish and within this greater circle was another circle of thinner feathers of an ash colour. The whole body was variegated cinereous and brown. The interior vanes of the long scapular feathers were white almost to the shafts. The lower belly was white and on the breast were long black spots. The first row of wing feathers had cross bars of black and a reddish-ash colour and the third row of the covert feathers of the wings had one or two white spots. The callous sole of the foot was yellowish.
Willughby considered both of the morphs to be of roughly equal size and not enough to be a differential feature. In the grey morph he examined, it only weighed 11½ ounces (326g). However, it was larger in length at 14½ inches (36.8cm) and in wingspan at 2 feet 11 inches (88.9cm). The tail was also longer at 7¼ inches (18.4cm).
Further Reading: John Ray, Francis Willughby's Ornithologia, 1678, p.102-3, T13, T14.
Author - Debbie Jordan, Middleton Hall Volunteer.
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