THE SANDWICH TERN. 703 



when worn) mottled brown-black, rest of central pair white but 

 other feathers with grey outer webs and distal portion of inner webs, 

 becoming brown-black towards tips ; whole under-parts white ; 

 primaries : outer webs duller silver-grey (becoming blackish when 

 worn) than adult, black line on inner webs broader and tips of 

 feathers black washed silver-grey with narrow white margin, inner 

 primaries with broader white at tip ; secondaries as adult but with 

 outer webs darker grey which extends on to inner webs of inner 

 feathers, innermost feathers barred black-brown as scapulars ; 



Ju.vei.ile of the Sandwich Tern (Sterna s. sandvicensis) 



greater coverts ash-grey, tipped white, innermost as scapulars ; 

 median coverts ash-grey, washed sandy-buff and with crescentic 

 black-brown bars near tips ; lesser coverts dark grey, narrowly 

 fringed ash-grey. 



First winter. — Like adult winter but feathers of nape not so 

 elongated or pointed, tail- and wing-feathers as juvenile, but new 

 wing-coverts as adult and juvenile ones with brown bars mostly 

 worn off, innermost one or two secondaries often renewed and like 

 adult and sometimes central pair of tail-feathers. The juvenile 

 body-plumage, varying number of wing-coverts and innermost 

 secondaries and sometimes central pair of tail-feathers are moulted 

 Aug.-Dec. First summer. — A complete moult takes place Mar.- 

 June, but outer tail-feathers sometimes not renewed and when 

 renewed dark grey at tips, sometimes not all secondaries. Plumage 

 like adult winter in all those examined. 



Measurements and structure. — $ wing 290-325 mm., tail : outer 

 feather 148-170, central 72-85, depth of fork 65-85, tarsus 27-30, 

 bill from feathers 52-58 (9 measured). $ wing 285-308. Primaries : 

 1st pointed, narrow, and about two-thirds primary-coverts, 2nd 

 longest, 3rd 14-20 mm. shorter, 4th 33-48 shorter, 5th 52-75 

 shorter ; outer web of outer primary very narrow. Outer second- 

 aries shorter than inner primaries, inner ones about as long as 7th 

 or 8th primaries, outer webs sharply sloped off at tips. Tail deeply 

 forked, 12 feathers, outermost pair much elongated, tapering to fine 

 point, rest becoming shorter, less tapering, and less pointed towards 

 centre, in juvenile outer feathers much shorter and less tapering, 



