NZ prepares: Warmer seas leads to higher divorce rates

Not everyone’s happy with rising water temperatures

After hearing that sea temperatures around New Zealand at the end of 2021 were 1.5C above average many Kiwis have arrived at the beach this summer with a smile on their face. However, the reality of a warmer ocean is not a happy one for all…
 
While albatross couples have traditionally stuck together year after year, a new study has linked a rise in water warmth is far higher rates of ‘divorce’ amongst these seabirds. 

While albatross couples have traditionally stuck together year after year, a new study has linked a rise in water warmth is far higher rates of ‘divorce’ amongst these seabirds. Yes, bird divorce is a thing.

A research team recorded nearly 2,900 breeding attempts in 424 females and also tracked bird breakups. They noted that when water was warmer the divorce rate rose from an average of 4 percent to nearly 8 percent. This may seem like a small number. It is not. This is because of the impact these divorces have on the breeding rates at important colonies.

The study has shown that warmer water can contain fewer nutrients and fewer opportunities for birds to eat well at sea. As a result, birds are arriving back in time for breeding with less energy and more stress. Partners are leaving each other, and less breeding is occurring.  

Researchers speculate that this stress is leading to relationship break-ups even when hatching is successful, causing further damage to the community of each colony and the raising of young birds.

Now in New Zealand we are experiencing first-hand the type of conditions that could spell disaster for our incredible albatross colonies.

When the sea temperature is above the 90th percentile for at least five days the classification of ‘marine heatwave’ is used. Such conditions have been found in all offshore regions around the country in November, and these heatwaves are on the rise year after year.

With news that many international albatross populations are under threat this latest study shows the previously unforeseen consequences of climate change. Just as increased flooding on land affect the kororā being able to source food, so to do other climate conditions have often hidden effects on our birdlife.

“It’s pretty obvious they love each other,” said Graeme Elliott, an albatross expert at New Zealand’s Department of Conservation who was not involved in the New Island study. “After you’ve been watching albatrosses for 30, 40 years, you can kind of spot it. They do all this stuff that we think’s important — human emotion stuff, you know — greeting the long-lost mate, and they love each other, and they’re going to have a baby. It’s wonderful.”

Climate Change Is Driving Some Albatrosses to ‘Divorce,’ Study Finds. Natasha Frost. New York Times, Nov. 29, 2021