Friday, 28 March 2014

Striated Pardalotes - juveniles

A juvenile Striated Pardalote - nominate Pardalotus striatus striatus
When we caught two young Striated Pardalotes Pardalotus striatus on the last trip to Charcoal Tank (see previous posts), I noticed that they were of different subspecies. The one above is of the nominate type striatus, which only breeds in Tasmania and spends autumn and winter on mainland Australia, where it overlaps the range of two subspecies, ornatus and substriatus. The nominate has yellow wing-spots, colouring on the tips of the greater primary coverts, while the subspecies have red wing-spots - see below.

The yellow wing-spot on the primary coverts of a  Pardalotus striatus striatus

The red wing-spot  on the primary coverts of a Pardalotus striatus substriatus
(The wide band of white on primaries differentiates this subspecies from the similar subspecies ornatus, which has narrow white edges to the primaries. See post of  17th September 2012)

A juvenile Pardalotus striatus substriatus
Then I noticed that the striatus juvenile's moult into adult type plumage was less advanced than that of the substriatus bird. In particular, its crown was still spotted rather than streaked like that of the substriatus (see below). This is only a sample of one from each subspecies, but I wonder whether the young Tasmanian striatus birds deliberately delay their moult until they have migrated across the Bass strait and settled in their winter range on the mainland. Meanwhile the resident subspecies of South-west New South wales, substriatus, begin their moult as soon as possible. Both birds were caught on the 15th March 2014. If the Tasmanian birds migrate from March-April (HANZAB), this bird would have been one of the earlier to leave. Would it have been one of the earlier to hatch too? If so the delay in its moult would be more likely a strategy to moult post migration. I would be grateful if anyone has more information on the plumages or migration strategy of juvenile Tasmanian Pardalotus striatus striatus.

Juvenile Pardalotus striatus striatus,
with a spotted crown

Juvenile Pardalotus striatus substriatus,
with a partially streaked crown


No comments:

Post a Comment