Arctic marine mammals may be subject to human-induced disturbance from vari
ous air traffic, mostly in connection with exploration and exploitation of
non-renewable resources. The escape responses (i.e. leaving the ice) of hau
led out ringed seals (Phoca hispida) to a low-flying (150 m) fixed-wing twi
n-engine aircraft (Partenavia PN68 Observer) during strip censuses in easte
rn Greenland (June 1984) and to a low-flying (150 m) helicopter (Bell 206 I
II) during reconnaissance in northwestern Greenland (May 1992) were recorde
d. Overall, 6.0% of the seals (N-tot = 5040) escaped as a reaction to the f
ixed-wing aircraft. Seals escaped less than about 600 m in front of the air
craft. The overall probability of escaping was 0.21 within a 200-m-wide cen
tre zone, 0.06 on the side of the aircraft (100-300 m from the flight track
), and 0.02 between 300 and 500 m from the track. The probability of escapi
ng was found to be influenced by the time of day, relative wind direction a
nd wind chill. Overall, about 49% of all seals (N-tot = 227 cases) escaped
as a response to the helicopter. Seals entered the water a maximum of about
1250 m in front of the aircraft. At wind chill values below 1100 kcal/m(2)
h, the probability of escaping was 0.79 in the 200-m-wide centre zone. On
the sides the probability of escaping decreased up to about 500 m from the
flight track whereafter it remained constant at about 0.30 up to about 1450
m. During the helicopter surveys wind chill was the only environmental fac
tor found to have an additional effect on the probability of escaping. The
study indicated that the risk of scaring ringed seals into the water can be
substantially reduced if small-type helicopters do not approach them close
r than about 1500 m, and small fixed-winged aircraft not closer than about
500 m.