One of the most eerily enchanting sounds in nature is undoubtedly the mesmerizing song of the blue whale. The song of the blue whale, the largest animal on Earth, can travel several miles away and while the exact nature, content, and purpose of these calls are not yet completely understood by the scientists that study them, researchers have recently discovered a trend in the pitch emitted by the singing whales.

A group of researchers have noticed a consistent trend in the songs of the blue whales which show a world wide change in the pitch of the sounds that are emitted by the whales. Scientists have been closely studying the songs emitted by blue whales which include at least 10 known songs, of which, this study covers seven. All of the songs for which data has been recorded have shown that the over all the pitch of the songs themselves have been steadily dropping in frequency with a change of 31% percent in pitch since the levels found in the 1960's. Scientists are yet uncertain about what is causing this change.

Among the possible theories that are being examined include possible changes due to global warming, the high levels of anthropogenic noise pollution in the oceans, changes in numbers among the population of blue whales, and changes in the physical size of the blue whales themselves in the years since the decline of whaling which had nearly driven many species of whales to extinction.

Global warming over the past few decades has raised the temperature of the sea which can also affect the properties of the saltwater itself, slightly altering its ability to conduct sound and effecting the ways in which sound waves behave in the water. This is one possible reason, or perhaps one of many variables, which has been discussed in the study that could possibly account for the change in the whale songs.

Another possibility is that with the rapid increase of anthropogenic noise pollution bombarding the oceans from ships, military endeavors, drilling, oil rigs, fisheries, and other sources the whales may need to change the frequencies of their signals in order to compete with all of noise that is present.

These a but a few of the possibilities that the research team has looked at; however, there has yet to be any concrete conclusion on the actual cause or purpose of the shift in the frequencies of the songs from the blue whales around the world. Whatever the cause, there is a clear indication that our activities are dramatically, and frighteningly, changing the dynamics of the ocean which in turn is effecting the entire planetary ecosystem.

The team of researchers behind this new study included Mark McDonald from Whale Acoustics in Bellvue, Colorado, John Hildebrand from the Scripps Institution of Oceanography at the University of California in San Diego, and Sara Mesnick with NOAA's Southwest Fisheries Science and the Center for Marine Biodiversity and Conservation for Scripps Institution of Oceanography, at University of California San Diego. The findings of their study was recently published in the scientific journal, Endangered Species Research and is available online.