Tern are not generally seen in large numbers at Skogsøy and are
outnumbered by Arctic tern. They turn up in early May, and are present
throughout the summer months until the second half of September.
The occurence pattern for this species seems very similar to that of Utsira.
The blue line shows number of visits, the orange one the number of
visits when Common Tern have been recorded and the green one
(numbers on right hand axis) shows the average
numbers I have recorded in any three day period.