BIRDS OF SOUTH-EAST NORTHUMBERLAND. 255 
winter this species gives place to the Herring-Gull, and adult 
birds are by no means numerous. This has been noticed by 
Selby, in his ‘ Catalogue,’ as being true for all the Northumbrian 
coast, but no mention is made of it by Hancock. Immature 
birds are present all the year round. It is extraordinary how 
incapable this Gull is of being able to immerse itself in water 
when swimming on the surface. I remember one day I ob- 
served a pinioned bird, at Tynemouth Park lake, which was 
trying hard to get a piece of bread lying on the bottom. It 
tried to duck, sink, and, by leaping up, plunge down, but all 
in vain, and the object of its desire was not twelve inches 
beneath the surface ! 
GREATER BuAcK-BACKED Guu (ZL. marinus).—A winter visitor, 
at which season adult individuals are quite as numerous as those 
of ZL. fuscus. My brother and I have examined numbers of this 
species in various stages of plumage, and the results of these 
investigations, although previously omitted, I include with all 
reserve: The male in most cases is a trifle larger than the female 
when both arethe sameage. The size of the immature increases 
year by year until the year before moulting into the mature 
plumage, probably the fourth; then the bird seems to have 
attained its largest size, and on the moult to full mature plumage 
the former looseness in the build disappears, and the feathers 
become more compact and close fitting. The difference in this 
character of the plumage between the immature and adult can 
often be discerned when inflight. The following table of average 
measurements from birds shot by my brother will illustrate the 
above :— 
IMMATURE. ADULT. 

Ist year, | 2nd year, | 4th year, | About 8th| About 6th 
Bo 



Oe One year, 9. | year, g. 
IDGIKNN  ssooo6dondoboGC 26-5 in 28:0 in 29°5 in. | 27:0 in 28°5 in. 
MMOL WAGs scien eee 18:0) 2) eS: 0719-0011 18:5 ao as-7e 
PM OLIDCAK Were storarelers ete 2:0); PH) POT in 2:0 ;; 2:4. ,; 
POL SAWCu re «clara eycuase LONG 355), 4:05 ,, 3°5 ,, 40 ,, 
», Of middle toe...... BHO) 43 3:0) 3; BO 55 3:0 ,, 30) 69 
Pe OM LALSUSial reteset scare G30) 3:0 ,, BI! on 30) 5 3-0 ,, 
,, ofmiddletailfeather| 6°9 ,, 7:0 ,, (Oe ue TW sc TO) 65 
Length from tip to tip of 
WANE Sisfete tats cvcvnvereie ciel 60:0 ,, 65:0 ,, 66:0 ,, OBO) 55 | Geka) 4 
WET OM tiiralerteetensptecvelestviis 3 lb. 33 lb. 4% lb. 4 |b. 3 lb. 9 oz. 



