THE SEA BIRD — LOCKLEY 349 



the rapidity of the Start Point and Frensham releases. Other birds 

 released in the Firth of Forth and as far north as the Faeroe Islands, 

 and as far south as France and North Spain, have also got back to 

 their nests on Skokholm in varying times. All these homing experi- 

 ments were vrithin the known range of the species. We needed to go 

 farther afield and see what would happen to birds released outside 

 that range. The farthest distance by sea for which we could easily 

 arrange without transport hardships for the birds — for we had to 

 be sure the birds were in good condition for a long flight — was Venice, 

 in Italy, approximately 3,700 miles from Skokholm via the Adriatic 

 and the Straits of Messina and Gibraltar. By courtesy of Imperial 

 Airways, two shearwaters from separate nests were sent to Venice, 

 the distance by air being a little under 1,000 miles. As far as I 

 know the Manx shearwater does not enter the Mediterranean and 

 therefore is not found in the Adriatic. Certainly ringing has so far 

 proved that our Skokholm birds in their winter wanderings do not 

 go beyond the Bay of Biscay. One of these two shearwaters is an 

 individual of some interest to us, for it has returned to its burrow 

 on Skokholm for five consecutive summers. It had already returned 

 safely from Frensham. Now it returned from Venice in 14 days. 

 It is impossible to say whether it homed over the Alps in a beeline 

 for Skokholm, or whether it found its way out through the Straits 

 of Gibraltar, or whether it crossed the backbone of Italy and then 

 over the Pyrenees to the Bay of Biscay. In any case it was a won- 

 derful performance. You can imagine our anxiety as night after 

 night we waited at Skokholm, and I must say that I did not expect 

 it to return. Meanwhile its mate had carried on very nobly, after 

 a w'eek hatching the egg, and then carefully tending the chick alone. 

 I can assure you that there was a great to-do in the burrow on the 

 fourteenth night when I went out on my regular inspection round 

 and discovered the parents together with the chick. Even before I 

 opened the nest I could hear their crooning conversation. I have no 

 idea what this may have been about, but an imaginative person might 

 have concluded that there was expostulation as well as congratulation 

 going on, and even the chick was chiming in with an odd squeak 

 here and there. 



The other shearwater may have returned from Venice in that 

 summer, but we did not catch it until the next spring, when it was 

 back at its usual nest. 



Similar experiments with sea birds have been made by workers 

 in America (7) and with similar results. Yet while these experi- 

 ments have proved a remarkable homing ability, we still have nothing 

 but theories to explain it, and the physiological mechanism remains 

 obscure. 



