 A study of an area of the Great Barrier Reef where the number of breeding great crested terns has grown ten @-@ fold , probably due to extra food from trawl by @-@ catch , suggested that lesser crested and sooty terns have moved away and now breed on a part of the reef where fishing is banned . It is possible that the large increase in the number of greater crested terns may have affected other species through competition for food and nesting sites . 
