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RE: storing a food source

Dann speculated "...(and no doubt insects for newborn snakes)"

In old books on Australian snakes you will often find statements that small
or juvenile snakes eat insects, presumably because even though nobody has
ever seen it - well, why wouldn't they?

I think Rick Shine reported (not sure if it's published) an adult King Brown
chasing a grasshopper once. However, as far as I'm aware, all cases of
insects in Australian elapid snake stomachs are consistent with secondary
ingestion (as gut contents of lizard or frog prey). First prey items of
newborns are often quite large in my experience (e.g. their siblings, in
several species closely related to Tigers), which can be risky to subdue and
swallow and hard work to digest, but gives them a good start in life. The
importance of the very first meal is a reason why venomous snakes are
born/hatch with plenty of venom, which may be more concentrated or different
in composition to that of adults (not sure if composition difference is
documented, Bryan Fry probably has looked into it).

Another example of highly seasonal food availability in a diet-specialised
snake is the lizard-egg-eating species of _Brachyurophis_. In most of their
range, lizard nests are only available for a couple of months in the year
(Summer or Wet), but I see _B. incinctus_ in fine condition here at the end
of the Dry. Definitely fat storage going on.

Dr John D. Scanlon, FCD
Riversleigh Fossil Centre, Outback at Isa
"Get this $%#@* python off me!", said Tom laocoonically.

-----Original Message-----
From: Dann Pigdon [mailto:dannj@alphalink.com.au] 
Sent: 17 September, 2009 12:23 PM
To: dinosaur@usc.edu
Subject: Re: storing a food source

On Thu, Sep 17th, 2009 at 8:48 AM, Augusto Haro <augustoharo@gmail.com>

> Thanks for the data on snakes. May it be that these snakes lower their
> metabolism after the abundance season? 

I suspect they'd almost certainly have to lower their metabolism, since
they'd be waiting for at 
least eight months for their next major meal. That doesn't stop them gorging
themselves on 
hatchlings when they're available though. I doubt they'd simply let the food
hang around in their 
stomaches undigested for that long though, so they'd pretty much have to
store fat on themselves 
for the lean times. This is thought to be why these island snakes have
undergone gigantism rather 
than insular dwarfism - to enable them to pack on as much fat as possible
(and to have the gape 
necessary for swallowing chicks).

>... and/or cannibally eating smaller individuals?

I'd think that such a strategy would quickly wipe out juveniles and drive
the subspecies (Notechis 
ater serventyi) to extinction. Most of the islands in the Furneaux group are
fairly small. Then again, 
females typically have between 20 and 30 live young at a time, so the
survival rate to adulthood 
wouldn't need to be very high.

Apparently they also feed on frogs and small mammals (and no doubt insects
for newborn snakes), 
however fully adult animals seem to rely mainly on seasonal gorging of
mutton bird chicks. "Rats 
and mice and such small deer" (er... frogs) would seem to be poor fare for a
2m long tiger snake 
as thick as your arm. The larger adults are probably not all that good at
catching small agile 
creatures anyway.



Dann Pigdon
GIS / Archaeologist                Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj