132 WILD LIFE ON A NORFOLK ESTUARY 



some nests contained three differently coloured eggs. Every 

 egg was blotched more or less with bluish -ash and dark 

 brown. 



The eggs of the common tern were easily distinguished 

 from those of its confrere by their larger size. In almost 

 every instance three eggs were laid, and most of them were 

 hard-set. I obtained an addled one of each species, and 

 understood that one clutch of young birds had already for- 

 saken their nest. We looked in vain, however, for any of 

 them in the adjacent marams ; they appear to be as capable 

 of concealment as the little ones of the ringed plover. Ex- 

 treme vigilance was necessary to avoid trampling on nests, 

 but we soon learned to "spot" them, thanks to Tom Cringle's 

 "trade mark" in the shape of a heel-pushed heap about a 

 foot away from each. With a few exceptions every nest of 

 the common tern was lined with coarse, sixpenny-sized pieces 

 of cockle and oyster shells, those of the little terns being 

 adorned by a handful of finer fragments. There can be 

 no doubt these pieces of shell are collected by the birds 

 instinctively for the sake of their useful retention of heat ; 

 they certainly do not add to comfort otherwise. All the 

 eggs were not only warm to the touch, but the lining of shells 

 was distinctly so also. Their ring-plover neighbours used 

 still smaller fragments. A few of the larger terns' nests 

 were lined with dry grass-bents, and formed really comfort- 

 able, cosy habitations. 



Here and there we came across patches of pebbles running 

 larger, many being of the size of the terns' eggs, others as 

 large as a hen's egg ; these seemed to be seldom wetted, 

 even by the sea-spray, and were of a blue-grey colour ; many 

 of them were plentifully spotted with a minute lichen, which 

 I have seen referred to as Lecanora aspersa, and also as 

 Lecidea petrcea^ the latter most probably being the correct 

 name. Wherever a trio of eggs had been located amongst 

 these the similitude was remarkable. I took a stone or two 

 home with me, and, placing egg and stones together, made a 

 coloured sketch of them, "just for the novelty" of it. These 

 lichen-spotted stones do not occur at Yarmouth, where all 



1 I forwarded a lichen-covered stone from Aldeburgh to the late H. D. 

 Geldart, who wrote : " I sent one of your stones to London to be named. The 

 spots on it are the Hypothalhis of Lecidea petrcea, a tolerably common lichen on 

 pebbles." 



