Lots washed up on the beach this weekend and probably this week as well. As it states below, it is natural mortality – the gruelling migration is perhaps nature’s way of sorting the weak from the strong to ensure a healthy breeding population. The lifeguards begin the task today of cleaning them up off the beaches.
The birds, mainly short-tailed shearwaters or Tasmanian mutton birds as they are sometimes known, are on their annual migration – one of the longest of any bird.
People are finding them on the beaches dying from exhaustion from Coffs Harbour to Bulli.
Short-tailed shearwaters are amongst the worlds’ most populous bird species. It is estimated there are 23 million breeding pairs in Bass Strait. However mortality rates during migration can be very high in some years – up to 1600 per kilometre in particularly bad years.
The shearwater’s chances of surviving their first migration can be slim. Short-tailed shearwaters leave Bass Straight in late April-early May, fly north east across the Pacific Ocean and on to the Bering Sea between Russia and Alaska to the Australian winter in the northern hemisphere. They live almost constantly on the wing returning to their islands via the east coast of Australia, to breed in late Spring and Summer.
Many are exhausted from the long migration and “crash” onto suburban and city beaches before they reach home. In some years, many hundreds of birds can be found dead or dying on beaches right along the coast of NSW.
A shearwater can lose almost half its body weight during the long migration so the chances of survival once washed ashore are very slim.
In some years very large numbers of short-tailed shearwaters are found dead or dying on NSW beaches. As alarming as this may appear, it is natural mortality – the gruelling migration is perhaps nature’s way of sorting the weak from the strong to ensure a healthy breeding population.