The secrets of seabird feathers: a new indicator of climate change?

A single seabird feather, like a strand of hair, hides myriad secrets.

It can tell us about the challenges and hardships a seabird has faced for a whole year, and it can tell us how climate change is affecting the environment. Like forensic work, feathers can be evidence that the ocean was abnormally hot that year or predict that a seabird population is in trouble.

Climate change significantly impacts the ocean and, consequently, food availability for seabirds and their chicks. These mighty flyers can travel incredible distances from land to find food. They can glide above the water for tens to thousands of kilometres, looking to spot squid, crustaceans, and sometimes fish, ready to dive for the hunt. But warmer waters are not ideal for their prey, and challenges in finding quality meals can cause them a great deal of stress.

It might sound strange but studying the stress response of seabirds easily compares to our own stress response as humans. Imagine that everyday shopping for food is uncertain, with regular items on your list either unavailable or in poor shape. You then seek an alternative supermarket further away, spending more fuel and time going to buy food every week.

Eventually, shortages in food supply will become widespread if the crisis continues. We know from research that when you are chronically stressed, you might notice you are catching more colds than usual or getting sick more often. In the long term, it can cause all sorts of health problems and limitations. In seabirds, a very stressed population may become unhealthy and struggle to raise their young.

But what happens when a whole generation of people grow up in an environment where scarcity is the norm? It’s likely we would see adults in poor physical condition as soon as a decade in. They would be physically weak and far from reaching their cognitive potential.

This is how climate change directly affects seabirds. Stressed animals are more likely to raise malnourished chicks who then become poor adults and mature into inefficient breeders. A population of birds that struggle to breed will likely suffer population declines in the future.

In Auckland, the seabird capital of the world, losing seabird populations is a serious issue. The highest biodiversity of these birds in the world occurs right here, in our own Auckland backyard. They play a vital ecological role as what scientists call ’ecosystems engineers’.

Seabirds bring nutrients deposited in their faeces, eggs, and feathers ashore. Their burrowing habits turn the soil and help incorporate marine-sourced nutrients into our coast. Islands and entire coastal forests depend on their presence to thrive, and they can be critical to the restoration of degraded terrestrial ecosystems. Yet, most seabird species are endangered and quickly declining. We need to act fast to get these birds - and our coast - out of trouble.

This is where the seabird feathers come in.

Stress hormones are deposited in the birds’ developing feathers as they grow up. Just like humans, seabirds increase the production of stress hormones when their environment is challenging. Variation in hormone levels can reveal changes in the environment and can become early signals of a population trouble.

As we can easily collect seabird feathers and measure the level of stress hormones in laboratories, we can use that information to make crucial decisions before the impacts of climate change become apparent to us when it's too late.

To make the most of this new tool, we need to test it thoroughly.

In our research on seabird feathers, and specifically the feathers of grey-faced petrels I study at the University of Auckland, our aim is to quantify the pattern of stress hormone deposits in the birds’ feathers. We then compare what we find to the birds’ overall population stability and what we have already measured as effects of climate change.

The feathers and their findings help us complete a big puzzle in the world of seabird ecophysiology, while also having promising potential for how we might use this new information to monitor the effects of climate change on our oceans and biodiversity. With environmental impacts quickly developing and seabird populations reaching critical levels, monitoring ocean health is urgent, but incredibly difficult and expensive.

Low-cost, non-invasive tools such as stress signs in feathers can reveal the state of our environment, and how that may affect our lives. My research helps validate this new monitoring technology, so it can be used with precision and confidence. It engages some of New Zealand’s most underestimated birds as a promising solution to complex problems.

Innovative applied science can help us protect our taonga species, their habitats and all of the critically important it plays roles in nature. A humble seabird feather might hold the secret to a better and healthier Auckland for us all.

*I use feathers of stressed grey-faced petrels, a seabird native to Aotearoa New Zealand.