MIGRATION 103 



instinct " in migrants. This theme has been most admirably 

 yet briefly handled by the late Professor Newton. By way of 

 illustration he cited the case of a "pair of Stone Curlews 

 {CEdicnemus crepitans) — a very migratory species, affecting 

 almost exclusively the most open country — which were in the 

 habit of breeding for many years in the same spot, though its 

 character had undergone a complete change. It had been part 

 of an extensive and barren rabbit-warren, and was now become 

 the centre of a large and flourishing plantation." Two other in- 

 stances quoted by Newton are scarcely less remarkable. Of these 

 one concerned "the nest of a Falcon {Falcoperegrmus)on Avasaxa 

 — a hill in Finland . . . — is mentioned by the French astronomer 

 Maupertuis as having been observed by him in 1736. In 1799 

 the nest was discovered by Skjoldebrand and Ascerbi. In 1853 

 Wolley found it tenanted, and from inquiries he made of the 

 neighbours it was evident that such had yearly been the case 

 so far as any one could remember, and so it was in 1855, as I 

 myself can testify." Continuing, he remarks: "In 1779 ac- 

 cording to one account, in 1785 according to another, a pair of 

 the Blue Titmouse (Parus cmruleus) built their nest in a large 

 earthenware bottle placed in the branches of a tree in a garden 

 at Oxbridge, near Stockton-on-Tees. With two exceptions 

 only, this bottle, or a second which had been placed close to it, 

 was tenanted by a pair of birds of this species from the year it 

 was first occupied until 1873, when I saw it; . . . but I regret 

 to add that I learnt through Canon Tristram in 1892 that the 

 occupancy had ceased for four years." 



Bearing these facts in mind, and applying them to British 

 birds, it seems to the writer of these pages that our annual 

 migratory visitants may be regarded with a tolerable degree of 

 probability as the direct descendants of the migrating hosts 

 which made their way to these islands when they formed part 

 of the mainland of Europe. The invading sea made its way by 

 slow imperceptible inroads. Though with the cycle of the 

 seasons the successive generations of these ancestral migrants 

 saw more and more water stretched across their path to the 

 summer breeding-home they heeded not, because the change 

 was so slow that none took note of it. By such gradual stages 

 was the barrier thrown across that no confidence was shaken. 

 The birds passed on, sure of what was beyond : and for this 



