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Re: feathers, poison, tree-climbing



At 12:24 04/11/96 -0500,  Nick Longrich wrote:
>       I was thinking about the feather thing again and I recall seeing
>an ostrich chick with a feathered neck. So it would seem that a feathered
>patch of skin must not necessarily stay so. I don't recall of any patches
>changing, however, to scales, but I wonder about ptarmigan feet- does
>anyone know if they lose those feathers in the summer?
>
>[Ostriches necks look "hairy" to casual inspection.  I presume those
> "hairs" are actually feathers.  Are you sure they lose follicles on
> their necks, Nick?  -- MR ]

Yes, Mickey, Ostrich feathers are definitely feathers.  Even bird
eyelashes are feathers, though they don't look it (and ostriches have dandy
ones).  There are quite a few birds that lose feathers from certain areas
as they mature, including many that develop bare ornamental patches (eg on
the heads of some birds of paradise and cotingas).

>        I was looking through my vertebrate bio text trying to find
>something on poisons, with little luck, although it occurs to me that all
>endothermic poisoners (those New Guinean birds with batrachotoxin, a
>different New Guinea bird with mildly poisonous flesh, platypi) are all
>using poisons defensively, rather than offensively, at least, all the ones
>I can think of.

We don't really know exactly what the male platypus does with its venom
spur, though it can be extremely painful to humans (echidnas, BTW, have the
spur but no venom gland).  However, one group of mammals that definitely
uses venom offensively is the Soricidae, or shrews.  Some shrews have
salivary glands that produce a poison that is used to immobilize small prey
such as insects; apparently humans can be affected too, painfully though
not, I think, fatally.  The best-known examples are the short-tailed shrews
of the genus Blarina.  So some mammals really do have a mouth-injected
offensive venom.