Observed the male perched adjacent to the nest with the female hunkered down after the big snowfall.  Incubating eagles will sit on the nest almost continuously.  The eggs need to be maintained at a temperature close to 105 degrees Fahrenheit.  Adults share incubation duties. Nest exchanges may occur after only an hour but usually take several hours between exchanges. Frequently the incoming adult brings a new branch or fresh vegetation for the nest, then the incubating adult carefully stands and takes off while the other settles over the eggs and rakes nesting material up against its body.  During nest exchange adults may both be in nest or sometimes one adult may leave eggs unattended for a few minutes before the other adult arrives and resumes incubation.  The first nest exchange of the day often occurs at or before sunrise, with next exchanges following every 1-4 hours.