Plastic pollution responsible for shearwater deaths
A contribution by Dan Burgin of Wildlife Management International Limited
Sitting on Buffalo Beach in Whitianga, if you look out towards the ocean past Devil’s Point, you can see a large rocky outcrop in the distance. Your eyes are looking at Ohinau Island, a small predator free island that sits just below the Mercury Island Group. Co-managed by Ngāti Hei and the Department of Conservation, the island is bursting with life, day and night.
My colleagues at Wildlife Management International Limited and I have had the privilege of visiting the island several times over the past six years for research. We monitor the toanui/flesh footed shearwater who call the island home. A medium sized seabird, you may have seen the species out on the ocean. With their characteristic pink feet tucked up to their tail feathers, they effortlessly ride the updrift of the surging waves as seabirds do, searching for food.
Their keen sense of smell often brings them around the back of any boat that is fishing. This intrigue has been their downfall with one of the key threats to the species being caught as bycatch in both commercial and recreational fishing activities.
However, another pervasive threat for this species of seabird is plastic pollution. You may well have heard of the stories of flesh-footed shearwaters on Lord Howe Island over in Australia, where the chicks are reported to have been fed large quantities of plastics by their parents. This hasn’t ever been reported in Aotearoa New Zealand, until now.
My colleague, Simon Lamb, and I were on Ohinau Island in May this year, undertaking a regular eight-day trip to check all of our study burrows and see which burrows have produced a chick. The chicks are all given a uniquely numbered metal band on their leg before they fledge and leave the island for the first time to move north into the Pacific Ocean for the winter.
They receive no guidance from their parents, just an innate instinct and inner compass that give them the drive to fly thousands of kilometres away.
The chicks are fed a mixture of squid and fish by their parents who tirelessly forage in and around the Bay of Islands and even as far out as the Louisville Ridge. For over 50 days, the chicks are wholly dependent on their parents to bring them food so that they can grow as big and strong as possible before leaving the breeding colonies.
Despite their best efforts to raise a healthy chick, the parents are unknowingly picking up plastics as they forage, either by mistaking the plastic itself as prey or because the plastic is already within their prey. Parents with a belly full of plastic come back to their underground burrow and unwittingly feed their chicks a deadly concoction.
During our trip in May, we unfortunately found 11 dead chicks within the breeding colonies that are monitored. When we looked closer, we found that within all the chicks’ remains, their guts were riddled with plastic fragments. In one instance, we pulled 113 individual plastic pieces from a single chick. In another instance, the plastic fragments came to a total weight of 35g. To put this into perspective, that is roughly the equivalent of five percent of the chick’s expected fledging weight (600g to 700g). For myself, weighing 68kg, that would be the equivalent of 3.4kg of plastic in my gut. It’s a lot.
The pieces of plastic ranged in size from less than 1cm to over 5cm with some having sharp edges and others smoothed round by the action of the ocean and possibly the digestive system of other animals.
When chicks are fed plastic fragments, the effects can be insidious. Sharp plastics can pierce the inner organs causing injury, block up the passages for food items and can lead to starvation as chicks are being fed a non-nutritious substance. Additionally, the chemicals that the plastics are made of can leach into the blood stream leading to a range of issues for the birds.
Looking at the chicks that were still alive, we couldn’t help but wonder if they had plastic inside them. In one moment of horror, a chick confirmed our suspicions by throwing up a thumbnail-sized piece of plastic while we were banding it.
This was of course deeply troubling for Simon and I. We care a lot about the fleshfooted shearwater and are immensely grateful for the opportunity to visit Ohinau and conduct research on the birds. However, we are increasingly worried. The solutions are not necessarily simple as plastics seems to be everywhere. Plastic waste has been found as far as the Arctic and Antarctic in our water, soil and even the air. When plastics are so ingrained in our daily lives, it is no wonder. Look around you now and you’ll be able to see a myriad of items that are made of plastic. There is no one silver bullet, but many tough challenges ahead for us all - on a personal level and right up to central government.
We need collective action. Of course, reducing the number of things you buy that contain or are wrapped in plastic is a great thing to do, and we recommend that, but we also need to be putting pressure on businesses, local councils and government officials to be doing more to better regulate plastic production, and develop and adopt alternative compostable packaging alternatives. Supporting shops and businesses that let us bring our own containers and talking about what we can all do among our friends, family, colleagues and community are of paramount importance.
If those flesh-footed shearwater chicks have shown us anything, it’s that we are in desperate need of change, not just for them but for ourselves.
The flesh-footed shearwater won’t be the only species dealing with the detrimental effects of plastic pollution. Aotearoa New Zealand is the seabird capital of the world. Nowhere else is there more seabird diversity in one place. This also means the risk is so much higher. Seabirds play an important biological role in our ecosystems - they are the intermediary between the ocean and the land, transferring valuable nutrients from the marine environment to the terrestrial environment.
Flesh-footed shearwaters are the sentinels of our oceans, they hold up a mirror to what is happening out at sea. What they are revealing to us is that our marine environment is full of plastic waste and our seabirds are suffering for it.
Pictured is Dan Burgin of Wildlife Management International Limited with a toanui/flesh-footed shearwater chick.