Pigeon eggs

[knarew1]

How long will fertilised eggs take to die if they have been unattended?

[wildwood]

It very much depends on at what stage the incubation is and the ambient environment temperature. Presuming it is 20c. outside.....

Before incubation, a fertile egg will last for up to 7 days, but viability will drop each day. (putting them in the fridge will not lengthen their viability)
Once proper incubation has started they can not be left for more than 10 minutes or so.
The last few days, say after 15 days, the eggs can be left for up to 2 hours but this doesn't do the embryo any good. Repeated breaks like that will certainly result in an addled egg.