Evidence 

Similarities between 79° and 70°, eg

• Feeding activity continuous / continues for 24 hours during polar day (summer months)
• feeding activity more intense in summer than in winter
• during times with a definite twilight period, (spring and autumn) feeding activity is

Predominantly diurnal

• during times with a definite twilight period, (spring and autumn) feeding activity is crepuscular (feeds at dawn and dusk).

Differences between temperatures:

At 79° 

• arrhythmic in summer and winter
• had less night-time feeding activity in spring and autumn
• less intense feeding in summer

At 70°,

• arrhythmic during summer only
• during the winter showed diurnal patterns / crepuscular activity (feeds at dawn and dusk)
• had more night-time feeding activity in spring and autumn
• more intense feeding in summer