810 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



mandible a narrow, raised, horny rirn with minute holes through 

 which aborted feathers grow on posterior margin ; this " rim " is 

 shed with rest of outer sheath of bill in autumn making whole bill 

 much smaller and base of different shape ; lower outline of under 

 mandible in summer slopes upwards gradually from base to tip, but 

 in winter, when outer sheath is shed, has a prominent angle. Nostril 

 a long slit near cutting edge of basal half of upper mandible. 

 Juvenile and until about one year old with comparatively shallow 

 and small bill without grooves, culmen sloping but not arched, 

 gonys about half length of lower mandible, angle prominent. In 

 second summer bill as adult but smaller, not so arched and distal 

 half with only two shallower grooves. " Rosette " of thick, 

 puckered skin at gape in adult summer, reduced to narrow band in 

 winter and young. Horny appendages, triangular above eye and 

 rectangular below eye, in summer adult are lost in autumn. * 



Soft parts. — Bill (ad. summer) basal rim of upper and margin 

 of lower and first ridge dull yellow, flattened proximal portion blue- 

 grey, rest bright red with extreme tip yellowish, rictal rosette and 

 inside mouth yellow, (ad. winter) proximal portion grey-brown, 

 distal half chrome-yellow shading to deep orange-red on culmen, 

 (juv.) proximal half dark grey-brown, distal half reddish-brown ; 

 legs and feet (ad. summer) vermilion, (ad. winter) yellow, webs 

 darker, (juv.) flesh ; iris grey-brown or whitish to hazel ; orbital 

 ring (ad. summer) vermilion, (ad. winter) red ; orbital appendages 

 (ad. summer) blue-grey. 



Characters and allied forms. — F. a. arctica (N. Norway, Iceland, 

 N. America) is a larger but not a well-defined form as measurements 

 overlap ($ wing 158-176, bill summer 46-55) ;| F. a. naumanni 

 (Spitsbergen) is still larger {$ wing 180-191, bill 50-60). Distin- 

 guished from other British Alcce by shape of bill. 



Field -characters. — Huge triangular brightly coloured bill and 

 orange feet prevent confusion with any other Auk. Not dependent 

 on vertical cliff faces like Common Guillemot and Razorbill, and 

 large nesting colonies occur in districts unsuited to those species. 

 The deep long-drawn guttural cry sounds like " a-r-r-r " or 

 " o-r-r-r " under different circumstances. 



Breeding-habits. — Breeds usually in colonies, sometimes of great 

 extent, in natural crevices or burrows, often excavated by bird, 

 sometimes in turf on face of cliffs or on grassy, low-lying islands. 

 Nest. — Scanty : a few bits of straw, or drift with generally several 

 feathers, bits of grass, etc. Fgg. — One only, often white, but traces 

 of markings generally discernible beneath surface. Occasionally 

 well-defined markings of brown or lilac, often in form of zone or at 



* For full account of moult of bill and eye appendages see Bureau, Bull. 

 Soc. Zool. de France, 1877, pp. 377-399 : abridged ZooL, 1878, pp.. 233-240 

 and plate. 



| Nine breeding birds from southern Norway (Stavanger) have the same 

 measurements as British, with one exception, viz. $ wing 170 mm. — H.F.W. 



