Re: egg-sposure (was Re: egg laying rates)

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

On Thu, 21 Mar 1996, Rob Meyerson wrote:
 Few birds ever leave the eggs completely ungarded for any
> length of time.  The only reason that the egg-eating snake can get
> the time to devour a whole egg is because the snake is hard to spot
> in the grass, and because theparents are away hunting/feeding.  In
> fact, there are a few ecological studies that suggest an inverse
> relationship between the amount of parental observation and the
> amount of nest destruction.  Those species that have a higher degree
> of nest destruction tend to be able to lay a larger number of
> clutches per breeding season to compensate.
> 
> how all this relates to dinos is anyones guess.

Because it once did relate, now it doesn't.

Nearly all surviving egg layers are extremely surreptitious about the 
location of their eggs.  There are other studies that suggest parental 
investment has a high cost in egg-predation because more trips to the 
nest mean higher chance of discovery.  Also, birds choose nest sites on 
the basis of the quality of camouflage - there is competition for sites 
that have more leaves to cover them.
        Dinosaurs were extravagantly above any threshold of discovery.  
Also, isn't it true that large herbivorous dinosaurs at least, needing to 
feed constantly, would have to be constantly away from the nest.  This 
would be especially true in times of environmental stress, i.e., the 
dinosaur would have to range further for a meal leaving its nest 
untended.  How much better to be a mammal and take your babies along for 
the meal.