Experiments were performed always at the same time of the day, to avoid interference with diurnal rhythms.
Finally, group living often provides diurnal rodents with better predator defenses.
A feature shared by many clock gene transcripts is that their abundance is subject to circadian and diurnal oscillation.
Accipitrids are diurnal birds of prey with broad wings, hooked beaks, strong legs and feet and sharp talons.
They have their own diurnal cycles, pegged to alien time-frames.
They are diurnal herbivores, hiding in reef crevices during nighttime and browsing over reefs to feed during the day.
When I was first married I was practically nocturnal, and my wife was diurnal .
The sample traces (a, b) are representative of the diurnal pattern of leaf extension rate for each species.
I'll get maybe three, four good diurnal emissions off per day, I reckon.
Right ascension makes it easy to use the apparent diurnal rotation of the celestial sphere as a means to telling time.