124 | Chapter 6
Sea Lions like to rest in this terrain, and I know from experience how
easy it is to round a tussock on Kidney Island and meet a surprised
200 kg sea lion bull with bad breath and a grumpy demeanour.
Fortunately Hedd survived and was able to report the geolocator
tracks of 19 shearwaters recorded over one or two years.^17 (See Map 8.)
These tracks perfectly show figure- of- 8 return journeys between the
Falklands and the principal non- breeding area, the continental shelf wa-
ters brimming with Capelin off the eastern Canadian Grand Bank. Most
starkly, there was virtually no overlap between northbound and south-
bound tracks in the North Atlantic, respectively west and east of the
Mid- Atlantic Ridge. That, of course, helps explain why European bird-
watchers are far more likely to see Sooty Shearwaters in the northern
autumn when the birds are heading back to their Southern Hemisphere
colonies, mostly along a surprisingly narrow corridor.
The shearwaters’ S- shaped sigmoid northward route is remarkably sim-
ilar to the northward journey described in Chapter 4 made by Arctic
Terns heading to breed in Iceland and Greenland.^18 Both species are ex-
ploiting the same winds at roughly the same time of year. Perhaps what
still requires explanation is why a minority of species, such as Sabine’s
Gull, apparently ignore the potential advantages of a following wind.
The figure- of- 8 trans- equatorial journeys in the Atlantic are repeated
with quite remarkable fidelity in the Pacific, for example by Short- tailed
Shearwaters.^19 After breeding on islands off Tasmania, most tracked
birds venture well into the Tasman Sea before heading north to two
critical non- breeding areas of high productivity in the North Pacific,
one off Hokkaido, Japan, the other surrounding the Aleutian Islands
stretching outwards from mainland Alaska. All the tracked shearwaters
begin their return migration to the breeding colony between mid-
September and early October. Birds travel in a south- westerly direction
through the central Pacific, skirting west of the Hawaiian Islands. After
crossing the Equator, the shearwaters continue south- west until reach-
ing the east coast of Australia. They then follow that coast southwards,
passing the subtropical surfing hotspots of the Gold Coast before mak-
ing landfall on the bleaker Tasmanian nesting islands.
One potential obstacle to these figure- of- 8 routes is the Equator. Here-
abouts there may be an absence of wind, doubtless a significant expla-