Why do female ball pythons (Python regius) coil so tightly around their eggs?

Question: What benefits does brooding confer to offspring viability that outweigh its costs to the nest-attending female? 

Organisms: Thirty captive Python regius females and their clutches. 

Site: Vicinity of Lomé, Togo. 

Background: It has previously been shown that brooding enhances ball python hatching success by reducing desiccation of eggs. 

Methods: We captured wild, gravid females just before the time of egg-laying. Then we varied maternal attendance, allowing it to last 0, 15 or 60 days. 

Conclusions: Brooding weakly influenced incubation temperature but markedly decreased egg mass loss owing to water loss and associated yolk coagulation. Brooded eggs produced larger, more active, faster swimming and more rapidly developing neonates than did non-brooded eggs.