Scotland's internationally important seabird colonies are continuing to have poor breeding seasons, RSPB Scotland has warned
The biggest population declines were in the northern isles.
Reserves in Orkney showed "significant" drops in populations of sensitive species such as Arctic terns and kittiwakes.
The RSPB called for areas where birds forage for food to be included in proposed marine protected areas.
The organisation said a full colony count at Marwick Head reserve on Orkney showed a "staggering" 53% decline in numbers since the last full census of the UK's seabird populations in 2000, and a 22% decline since the last colony count in 2006.
Guillemots and kittiwakes failed to produce a single chick at Noup Head on Orkney, while on the North Hill reserve breeding pairs of Arctic skuas were down by nearly half.
The single remaining pair of kittiwakes failed to raise any young at a colony which once had more than 150 pairs.
In the Western Isles and Inner Hebrides numbers were low, with nesting also hampered by gale force winds in May, which particularly affected terns.
On Shetland there was some success with 15 occupied burrows of Leach's storm petrel, the only RSPB site where the birds are found, but the picture was "bleak" elsewhere on the islands.
The east coast generally showed an improvement from the previous year, but overall numbers of guillemots and kittiwakes fell significantly over a 10-year period.
Arctic skua numbers on one reserve dropped by nearly half
Troup Head on the Moray coast reported the biggest drop in guillemot numbers, experiencing a massive 66% decline at the reserve since 2001.
Source: BBC News