Bettie Beech, of Palmerston North, asks :-
Why do most land birds have a tuneful song, whereas most sea birds seem to have a raucous call?
Dianne Brunton, an ecologist at Massey University's Institute of Natural Sciences, Albany, responded.
Bird songs or calls are a fundamental aspect of their communication with one another and are used to attract a mate and establish territories, communicate with offspring, and warn mates/chicks about approaching predators or danger.
Birds inhabit most of the different environments found in the world and birds range in size from tiny hummingbirds to large albatross. Birds can be divided into passerines and non-passerines. Passerines are songbirds and along with hummingbirds and parrots are able to learn songs. Non-passerines generally have stereotypical simple songs or calls. However, sound is a wave and waves are altered by the physical environment: where they are reflected, refracted, and absorbed. Different wavelengths or frequencies are altered by the environment in different ways.
For example, in forest ecosystems, the best 'sound window (the optimum frequencies for clear sound propagation) occurs between 1.5 kHz and 2.5 kHz. This will be very different for marine habitats which also have extensive background noise due to wind and surf. Nonetheless, song divergence is also related to a species morphology and phylogeny. Seabirds tend to be large birds and from non-passerines ancestry. Forest birds tend to be small and from passerine (songbird) ancestry. In the case you outlined, morphology and phylogenies provide a more general explanation for acoustic differences between seabirds and forest birds.