Re: Re-emergence of lost features.

[John Bois <jbois@umd5.umd.edu>]

On Mon, 16 Mar 1998, Paul Willis wrote:
> Slow down a bit mate. While this makes a nice, Just-so story, I'ld like to
> see more information on egg predation in rattites. As I understand it, the
> main egg-predator on both Ostrich and Emu eggs is from varanid lizards, and
> they have a pathetic brain case compared to a marsupial.

Of 57 nests in a wild ostrich study, Brian Bertram found the following:
6 destroyed by jackals
8 by hyenas
9 by hyenas and/or jackals
6 by Egyptian vultures

I think you're probably right about emus though I haven't been able to
find anything on the subject.

Varanids are well known, as you know, for attacking croc eggs.  But these
eggs are in a somewhat predictable location, i.e., near the water (if
anyone is interested I have a paper which describes an extended game of
cat and mouse between nest guarding crocs and pesky varanids).  I don't
know what sort of olfactory ability they have--but there is that tongue!

In the tropics of some countries, the people talk about a parasite load or
a worm burden.  The deal is that many folk are carrying some infestation
but it is tolerable unless it becomes too severe. I imagine this is
similar for oviparous species: they can tolerate some basal level of nest
predation but an influx of novel speciation might tip them over the
edge.