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Hi Russell and all
Thanks for the enthusiastic response.
Calidris canutus has had a hard run from the start. You may not know
that the Red Knot acquired that name because King Canute fancied the bird as
table fare! Genetic diversity indicates that there was a "bottleneck" event
around the beginning of the last interglacial period where their numbers fell to
around 500 birds. This was due to the effects of glacial movement and other
climate change events upon their breeding grounds. Things are not getting any
better for the embattled bird nowadays either, it appears.
You're not alone about not knowing much about
Calidrid foraging/feeding methods and adaptations, as practically nobody else
does either! Last I heard, it is suspected that Great Knots use a similar
battery of foraging tools to the Red Knot but probably in combination with
others too.
I'm not certain about other waders, but I can add
that the vast variety of bill structures are indicative of differing
culinary preferences and the requisite foraging tools and procedures which go
along with this. This goes hand in glove with a wonderful thing called "Resource
Partitioning". Evolving a different bill or foraging technique enables you to
sidestep the competition on the mudflats and thus increase your numbers (and
success as a species) significantly. This can even occur between males and
females of the same species and is quite common among waders (fans of Crested
Shrike-tits and some treecreepers will recognise this too). This "Intra-specific
Resource Partitioning" can also reflect different nutritional needs for the
sexes in waders as much as offering the opportunity for each sex to
sidestep competiton between each other. In a number of cases females must arrive
at breeding grounds practically ready to lay and at least several species
appear to have the capacity to carry the resources for this. There is even
research which indicates that Eastern Curlews increase their skeletal mass by as
much as a huge 30% pior to migration, so that they have the calcium on hand to
produce eggs in their north Asian breeding grounds! Talking about packing your
bags before you fly! You'll also note that among many species of waders the
females are considerably larger than the males.
As for the Bush Administration's
monetary/military excuses for pulling the plug on a raft of urgent convervation
programs in the US . . . GW Bush believes that when the last tree is
cut down Jesus will return. Unfortunately, Calidris canutus rufa
wont be around to care.
Ricki
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