bonaparte's gull. 729 



sometimes with slight sub terminal edging of black and some primary 

 coverts with black shaft-streaks of varying width. 



Measurements and structure. — $ wing 264-276 mm., tail 100- 

 106, tarsus 35-38, bill from feathers 28-31 (12 measured). $ wing 

 250-272, bill 27-31. Primaries : 1st narrow and about two-thirds 

 primary-coverts, 2nd longest, 3rd 2-5 mm. shorter, 4th 15-23 

 shorter, 5th 36-40 shorter ; outer web of 2nd very narrow. Outer 

 secondaries shorter than 11th primary, tips of outermost square, 

 of rest with notched point, outer webs being sloped off, innermost 

 between 7th and 9th primaries, tips sharply rounded. Tail almost 

 square, 12 feathers, tips fairly square but more rounded in juvenile. 

 About one-third of tibia bare, tarsus and toes slender,- hind toe 

 minute, elevated and free, three front ones connected by concave 

 webs, claws short, rather blunt and slightly dilated on inner edge. 

 Bill slender, compressed, upper mandible straight for rather more 

 than half its length then curving down to tip, gonys sloped up to 

 sharp tip, angle distinct but not very prominent. Nostrils sub- 

 basal and slit-like. 



Soft parts. — Bill black, inside mouth orange -vermilion ; legs 

 and feet (ad. summer) orange -vermilion, (winter) flesh-colour, 

 (juv.) dusky ; iris brown ; orbital ring black. 



Characters. — No subspecies. In summer blackish-slate head and 

 in all plumages dark bill and want of black on inner edge of inner 

 webs of primaries distinguish it from L. ridibundus. 



Breeding-habits. — Haunts wooded districts and usually nests on 

 side branches of spruce firs, 4 to 15 or 20 ft. from ground. Nest. — 

 Built of small sticks, twigs, etc., lined grasses and moss. Eggs. — 

 Normally 2 or 3, rarely 4, ovate, ground-colour varying from 

 brownish -yellow to deep olive-buff, spotted and blotched with 

 occasional scrawls of dark olive and umber-brown. Average of 29 

 eggs, 49.05x34.13. Max.: 52.5x34 and 50x36. Min. : 44.5x35 

 and 47x32.5 mm. Breeding -season. — From second week June till 

 end of month. Incubation. — No information. Single brooded. 



Food. — Largely insects and their larvae, including lepidoptera 

 (moth pupse), diptera and larvse (Coleopa frigida, maggots, etc.), 

 hymenoptera (ants and pupa3), but also on coast, small Crustacea, 

 annelida and small fish. 



Distribution. — British Isles. — Seven. One near Belfast, Feb. 1, 

 1848. One Loch Lomond (Clyde) about end April, 1850. One 

 Falmouth, Jan. 4, 1865, one Penryn, Jan. 10, 1865, and one 

 Penzance (Cornwall), Oct. 20, 1890. One St. Leonards (Sussex) 

 early Nov., 1870 (Saunders, p. 661). One St. Leonards, Nov. 3, 1913 

 (Brit. B., vii, p. 235). 



Distribution. — Abroad. — Breeds in Arctic America from Alaska 

 and north Mackenzie to British Columbia and south Keewatin. 

 Winters from Maine to Florida, Texas, and Yucatan and on Pacific 



