Off shore wind farms act as hunting grounds for seals, a new study shows.

Researchers at the University of St Andrews used GPS tracking to monitor seals' movements. The team found that the animals regularly visited offshore wind farms and looked for food. Scientists believe that the artificial structures are acting as man-made reefs and altering animals' behavior.

The study was conducted by Dr Deborah Russell and is published in the journal Current Biology.

Movement of seals around wind farms and water pipes surprised Russell and colleagues.

For the study, scientists tagged harbor and gray seals on the British and Dutch coasts of the North Sea. They found that 11 harbor seals near two active wind farms - Alpha Ventus in Germany and Sheringham Shoal in the southeast UK. Researchers found that the seals moved in a grid-like pattern near the farms.

"I was shocked when I first saw the stunning grid pattern of a seal track around Sheringham Shoal" - an offshore wind farm in Norfolk," Russell said in a news release "You could see that the seal appeared to travel in straight lines between turbines, as if he was checking them out for potential prey and then stopping to forage at certain ones."

The team has found that man-made structures in oceans affect marine animals, but hasn't really shown the extent of this change in behavior.

"Only a small proportion of our study seals utilized wind farms or pipelines," Russell said in a news release. "At present these structures cover a small proportion of the extent of the at-sea distribution of seals. As wind farms become more extensive, many more seals will likely be affected."

Researchers hope to carry out further research to understand how massive developmental projects affect animal populations.