Wildlife surveys have also found birds that have become tangled up in balloon ribbon and string restricting their movement and ability to feed.
Hefyd mae arolygon bywyd gwyllt wedi dod o hyd i adar sydd wedi cael eu dal yn y rhuban a'r llinyn sydd ynghlwm wrth falwnau, gan gyfyngu ar eu gallu i symud a bwydo.