Thanks to everyone who replied to my 'Curlews, godwits and canals' message -
I've already answered several queries directly.
Nobody really offered an answer to the question as to why curlews are first
at my local roost site and godwits are last, although there were one or two
interesting suggestions. Perhaps Danny Rogers provided the most relevant
comments (relating to digestion pauses) although, as he indicated - why the
godwits choose to loaf and digest on their preferred high-tide roost for as
long as possible - instead of doing so on the flats like the curlews - is a
mystery to me." Incidentally, I've not observed that the curlews stop
foraging before the other waders, including the godwits.
Danny is absolutely right when he suggests that the missing preferred roost
of the Barwits and Great Knots is a relatively exposed and open site. In
fact, it's not 'missing' - it's well known and observed. Curlews leave
there early whilst godwits retreat from the incoming tide and compact, only
to leave if really necessary (i.e. high tide). Both curlews and godwits are
back there feeding an hour or so after the tide starts falling.
How about this for a (simplistic) answer. Curlews need much more space
between them when roosting. This is certainly true when they are feeding,
when there's perhaps one curlew per two hectares (tell me if I'm wrong). At
the roost site I'm watching I'd guess that the average distance between
curlews is several metres (taking the base of bill as a point source, for
e.g.). When the godwits compact at their preferred roost site there's
hardly any space between them, and even when they've flown in to the roost
site I'm watching there's considerably less than a metre between them.
So, is this fair comment. Have any studies been made on the area that
different species of wader need at roost sites? Has anyone observations
that support this theory - or otherwise? It could be an interesting factor
when trying to decide whether some species of wader could adapt to another
roost site (i.e. an alternative or artificial site) when their original
roosting area is being wilfully destroyed. Sorry, I'll stop before I get
emotional !!
Feedback please.
Trevor.
PS. Danny - were you run over by a hovercraft?
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