THOUSANDS of migratory birds have been found dead on south-west beaches with wildlife experts believing a fish shortage has led them to starve to death. Walkers and horse-riders were puzzled to find nearly 50 short-tailed shearwaters lying dead between the Breakwater and the Warrnambool Surf Life Saving Club early yesterday.Police were also called to investigate what appeared to be blood in the water, but most observers later concluded that it was a type of algae. Warrnambool horse trainer Tammy Good said she first noticed the algae on Thursday morning but it had become much darker by yesterday. One of her horse riders counted 47 dead shearwaters at Lady Bay, as well as a number of sick birds on the sand or struggling in the shallows, and more at Killarney beach. Department of Sustain­ability and Environment (DSE) senior biodiversity officer Mandy Watson said the deaths were first reported two weeks ago at Nunns Beach and Bridgewater beach near Portland.They have since been found east of Warrnambool along the Great Ocean Road, prompting several calls from concerned members of the public, she said. Ms Watson doubted that the water discolouration and the bird deaths were related. Yesterday’s death toll in Warrnambool, along with reports of up to 100 more dead shearwaters on Port Fairy’s East Beach, was a concern.The DSE last night sent 10 birds from Killarney, Levys Point, Port Fairy and Warrnambool to Werribee for a post-mortem, and a cause-of-death was expected today. “The shearwaters have not long ago finished their migration from Russia down here for breeding,” she said.“They’re very hungry, they’re on the edge. “And if there’s no fish you can get a die-off occurring but I’ve never seen anything like this go on for so long. “We have also had reports of dead fish, dead starfish,” she said.An autopsy of the birds found at Portland two weeks ago found they had starved to death.Tests found no clear evidence of any toxic substances, she said. Up to 70 shearwaters, commonly known as “mutton birds”, were found dead on the NSW south coast two weeks ago. The unseasonally high temperatures may have contributed to less fish in the area, which in turn could have led to the mass starvation, Ms Watson suggested. South-west councils are working to collect the dead shearwaters and Ms Watson urged the public not to touch them.Those who find large numbers of other species of dead birds or fish are asked to contact the DSE.An Environment Protection Authority spokeswoman advised swimmers to avoid the red algae in the water.