The Xatitus Murrelet 
No. 296 
Xantus’s Murrelet 
A. 0. U. No. 25. Endomychura hypoleuca (Xantus). 
Synonym.— White-bellied Murrelet. 
Description. — Adult: Above and on sides (including axillars) slaty black, the 
plumbeous tone faintly differentiated as skirting of feathers on back and wings; a touch 
of white on either eyelid; below pure white, the lining of wings either pure white or 
mingled in varying proportions with smoky gray. [Most published descriptions of 
E. hypoleuca give “wing-lining pure white” as a diagnostic character, and the name 
Endomychura (Brachyramphus) craved (Salvadori) has been given to an alleged southern 
form on the sole ground cJf smoky gray wing-lining. But the fact seems to be that 
E. hypoleucus exhibits every degree of gradation from pure white to pure smoky. At 
any rate, every variation within these limits is found off Monterey in winter. If this 
be not the true explanation, then a new form having wing-linings of pure white and 
characterized by a shorter beak must be set off from the bulk of mottled smoky-and- 
white birds—and there is material in the Berkeley museum to support such a view.] 
Bill black; iris brown; feet “whitish blue.” No recognized seasonal changes. Downy 
young: Above bluish black; below pure white. Bill black; feet paler. Measurements, 
average of 10 Monterey specimens: length 246.8 (9.72); wing 118.2 (4.65); bill 19.4 
(.76), depth at angle of gonys 5.4 (.21); tarsus 23.7 (.93). 
Recognition Marks. —Robin size; black above, white below; amphibious habits. 
Requires careful distinction from B. marmoratus (see under foregoing). 
Nesting. — Eggs: 1 or 2; placed at end of short burrow or in crevice or cave, or 
under rock of sea-girt islet; variable in shade, and often exhibiting the most abrupt 
diversity between “mates,” dull white (rarely), olive-buff, greenish olive-buff and 
pinkish olive-buff (avellaneous) to dull tawny olive or even dresden brown and cinna¬ 
mon-brown; marked variously with purplish black, brownish black, deepest chocolate 
or intense bister. Some specimens are nearly immaculate; in others the color is finely 
and uniformly sprinkled over the entire surface; others are “cloud-capped” or hand¬ 
somely wreathed about the larger end. Av. size 53.5x36 (2.11 x 1.42); index 67.3. 
Season: March-July; one brood. (The extremes of the season probably represent the 
activities of diverse stocks or tribes.) 
General Range. —Coasts and islands of southern California and western Lower 
California. Breeds sparingly as far north as Anacapa Island, and wanders further at 
the close of the breeding season (?), probably as far as Tomales Bay (Nov. 10, 1910). 
Authorities.—Coues ( Brachyramphus hypoleucus), Proc. Acad. Nat. Sci., 
Phila., vol. xx., 1868, p. 64 (coast of Calif.); Beck, Proc. Calif. Acad. Sci., ser. 4, iii.. 
1910, p. 60 (Monterey Bay; occurrence; crit.); van Rossem, Condor, vol. xvii., 1915, p. 74, 
figs, (crit.; relationship of hypoleucus and craveri ); Howell, Pac. Coast Avifauna, no. 
12, 1917, p. 22 (s. Calif, ids.; habits; occurrence, etc.). 
THE OPEN SEA is its home. Our little diver finds safety and food 
far from land and the waiting enemy, the grim Duck Hawk. On or near 
the surface it rides out storm or sunshine until darkness makes possible 
a return to its island. 
14.89 
