56 Proceedings. 



screens. As soon as the trees were bigli enough the Wood 

 Pigeons built in them, but the Stock Doves kept to their 

 burrows; at last the "brecks" were ploughed up, and the 

 birds dispossessed. For two or three years they were at their 

 wits' end, laying their eggs, says Mr. Stevenson in his ' Birds 

 of Norfolk,' in the bottoms of the hedgerows ; but, wiser coim- 

 sels prevailing, they eventually took possession of the young 

 timber, building at a greater height than the other species. 



About the same time, when planting became general in 

 West Norfolk, a colony of Herons, which had nested fi.-om a 

 time beyond memory upon the f/round among the fens, removed 

 all at once to a plantation which had reached a respectable 

 height, the growth of which had evidently interested them 

 and been the subject of consultation perhaps for years. 

 Incidents such as these, both of which rest upon the authority 

 of Mr. Stevenson, give us a clue to the enigma which pre- 

 sents itself when we see the Stock Dove thriving on the south 

 coast, and the Rock Dove become extinct there within the 

 present century ; the Heron hold its ground, whilst the 

 Bittern and Spoonbill die out. 



In the successful species we have evidently birds possessing 

 an adaptive faculty, of which the Swallow, the Martin, and 

 the Swift are eminent examples. Where did these birds 

 breed on these islands before the era of chimney-stacks and 

 well-roofed houses ? They must have been exceedingly local, 

 the Swallow especially, which I have never met with nesting 

 in a strictly wild condition, for the Martin and Swift breed 

 on the sea-cliffs, and the former at Malham Cove, in York- 

 shire. So successfully has the Swift accommodated itself to 

 its new conditions that I think it outnumbers within the 

 borough of Reading the combined forces of Martins and 

 Swallows ; indeed there are some reasons for suspecting that 

 it begins to find nesting-sites scarce here, for I have seen it 

 breeding behind the loose face of a church-dial, and under 

 the eaves of low-built cottages and new suburban viUas, 

 scarce eighteen feet fi-om the ground, searching the eaves of 

 small and new houses, and wriggling in and out of the inter- 

 stices of some carved stonework in front of a warehouse. 



