adUlt migrations | 53the urge to wish it well ahead of the imminent life- and- death combat in
the dark under immense pressures that would crush the housing of an
everyday underwater camera. Even without photographic or observa-
tional back- up, we are ready to believe such battles take place because
how else would the whale’s stomach come to be filled with squid bits.
Similar deduction has improved knowledge of the extremes of bird
migration. As the autumn equinox approaches western Alaska, Bar-
tailed Godwits, wading birds standing 30 cm tall on spindly legs, are
becoming restless. One night, often when a tail wind from the north is
blowing, they leave Alaska for the south. Across the vast swathe of the
Pacific Ocean south from Alaska, islands are desperately far apart. More-
over, few Godwits are ever seen on the scattered atolls at this season.
Nor are the Alaskan birds, some of which carry leg tags, seen on the
continental rim of the Pacific. Yet, late September and early October
witness the arrival of the Godwits at New Zealand’s estuaries. Is it possi-
ble that the birds fly from Alaska to New Zealand in a single 10,000 km
flight, losing at least half their take- off weight* en route? Such seemed
very likely but it was only when satellite transmitters were attached to
the birds in 2006 and 2007 that the non- stop week- long journey was
confirmed.^1
Deduction has also pointed to the likelihood of other remarkable
migratory feats. Blackpoll Warblers winter in northern South America
and breed across North America from Newfoundland to Alaska. Check
an atlas and the obvious southbound route from New England to Co-
lombia or Venezuela is a direct flight across the Gulf of Mexico. Such
a feat had long been suspected of these 12 g birds because of radar evi-
dence (echoes from small birds heading seawards at the appropriate sea-
son) and because of the scarcity of these warblers along the United
States’ eastern seaboard anywhere south- west of North Carolina in au-
tumn. Only the fitting of 0.45 g geolocators to 37 Blackpoll Warblers in
Vermont and Nova Scotia in the summer of 2013 clinched the issue. Five
Warblers were recaptured the following spring and the downloaded
- (^) The birds set forth from Alaska at a mass of 325– 400g. About 55 percent of that mass is fat
which is probably almost entirely used by landfall.