Blackbird query

A pair of blackbirds built a nest some time ago in our jasmine but instead of the female continually sitting on it as she has done in the past when incubating her eggs, it is left unattended for most of the time and she only sits on it for brief periods. Any ideas please as to what is going on – will eggs be laid or is she just going there for a rest from the hustle and bustle?!  thanks