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It's the case with many species of waders that
the juveniles remain in Australia for the first year or two of their lives. Upon
reaching maturity, they join their older peers on the Flyway. I recently heard
that Sharp-tailed Sandpipers are of breeding maturity from their first year and
so join the adult population from the first migratory departure. Therefore, the
only birds which remain would be sick or injured individuals.
We have noted up here at Broome that, with
the migration now dwindling, some birds are eager to depart but appear to
have left it too late. There are not enough fellow species to join them and thus
share the load in Vee formation which is required for them to complete the
mostly non-stop journey to the Yellow Sea. Each evening we see these birds
begin to head north repeatedly but return to the bay after a short while.
None are specifically colour banded, so I can't state for certainty that
individuals are failing to depart due to lack of fellow travellers, but it
certainly appears to be the case that late starters are non-starters and thus
doomed to remain with the sick, injured or juveniles and snack on good old
aussie inverterbrates all winter here at Roebuck Bay.
Ricki
Broome WA
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