|
Hi,
Peter Madvig is right, there's a mistake in HANZAB.
The measurements of wing, bill, tarsus and so on in the back of the HANZAB texts
were taken from museum skins, specifically for HANZAB, and they are a good guide
to the size of the birds. However, the total length measurements given at the
start of the HANZAB texts were a perennial headache. Total length is a
measurement that can't be taken reliably on museum skins (as the length of a
skin depends on how much the preparator stretched it). We did get some data from
labels (some preparators measured total length of a specimen before they
began to to take the skin off), but those measurements were often wildly
inaccurate. We did our best, but sometimes we had to resort to published
literature as a source. The literature wasn't great, as other book authors have
had the same problems and have often copied one another.
I'd guess that's the problem with the godwit total
length measurements in HANZAB, though the more specialised measurements in the
back should be fine. The size difference between the two in the field is
interesting. Both Bar-tailed and Black-tailed Godwits vary geographically.
Europe has the smallest Barwit race, Eastern Australia and NZ has the biggest.
In contrast Black-tailed Godwits are biggest in Europe, and we get the smallest
subspecies (melanuroides) in Australia. As a result, in Australia Black-tailed
Godwits are clearly smaller than Bar-tailed; in Europe it's the other way
around, with Black-taileds being larger than Bar-taileds. It has in fact been
suggested that east Asian Black-tailed Godwits should be split off as a full
species, but I don't think any DNA investigations of this idea have been carried
out yet.
Danny Rogers
|
