NAVIGATION BY SEA-BIRDS I59 



By airline Venice is only 930 miles from Skokholm; and one bird 

 got back in 14 days. At the time of this experiment this instantaneous 

 correct orientation on release in fine weather was regarded as remark- 

 able, but thought to be accidental; as were also the correct orientations 

 of some other shearwaters released in the Alps. However the latest 

 work by G. V. T. Matthews with shearwaters from Skokholm has 

 confirmed that there is an immediate initial orientation of this species 

 when released inland in fine weather; returns to Skokholm were at 

 high speed (from Cambridge, 230 land miles in 6|, 8, 8, and 8J hours, 

 from Birmingham, 156 miles and London, 225 miles, in 17J hours). 

 In heavily overcast weather birds released at Cambridge showed an 

 initial random scatter and none returned until the third night 

 (Matthews, 1952). Finally the latest shearwater test by Dr. Matthews, 

 arranged by one of the writers, has created a world record for a ringed 

 bird used in a homing experiment. A Skokholm shearwater, conveyed 

 by our friend Rosario Mazzeo to Boston by air and released on 3 

 June 1952 at the edge of the airport which fringes the sea there, 

 returned to its nest burrow at Skokholm on 1 6 June. It covered the 

 3,200 (land) miles across the Atlantic in 12 J days, thus averaging 

 250 miles a day, or more than 10 miles an hour. Even swallows 

 (128 miles a day) and terns (139 miles a day) used in earlier tests have 

 not equalled this speed. For a reason which is discussed below it is 

 possible that this Boston-Skokholm shearwater may not have travelled 

 at night; in any case we must allow it at least four hours average a 

 day for feeding, preening and resting, and we must also allow for time 

 lost as a result of its normal swinging deviating flight which makes 

 its surface speed probably a third less than its flight-speed. It is clear 

 that this bird had not time to spare for random searching, and yet 

 the Manx shearwater does not visit the North American coast except 

 as a very rare straggler. It was a fine clear morning when it was released 

 at Boston and it immediatly flew eastwards in the direction of the open 

 Atlantic — and Skokholm. This initial correct orientation cannot be 

 explained satisfactorily by stating that it was accidental, or that a 

 sea-bird would naturally fly away from the land; our shearwater at 

 Venice turned inland towards high mountains, and Matthews' shear- 

 waters in London and Cambridge flew at first further inland (in order 

 to reach Skokholm quickly) rather than eastwards to the nearest sea. 

 Initial orientation almost (in some instances quite) on the right com- 

 pass bearing in fine weathei' and unknown territory can only be 

 explained by the possession by the shearwater of an orientation 



