Albatross mating has taken some heat from global warming, according to a recent study published in the Proceedings of the Royal Society. Researchers studying black-browed albatrosses (Thalassarche melanophris) noticed that climate change was affecting relationship stability. As the seas got warmer, albatross divorce rose, and previously bonded pairs split up and went looking for new partners. If you’re reading this and wondering, “Are all birds monogamous?” the answer is mostly yes, but it seems climate change is affecting bird relationships.
Are All Birds Monogamous?
A lot of bird species are monogamous — more than 90% according to Science News. Pairing for life confers huge advantages, with a stable pair bond increasing breeding success. There’s a shared familiarity with territory and food resources, leading to more effective nesting and food gathering. Hatching eggs is hard work, and sharing nest duties helps spread the load for incubating and then feeding the hungry chicks.
Albatross mating is often held up as a prime example of monogamous bird bonding. Adults spend most of the year at sea hunting for food before returning to the nest site to breed. Having a strong pair bond not only ensures this synchrony, but once the egg is laid, it also reassures the partner left sitting on the nest while the other feeds, often spending weeks away. However, strong pair bonds are becoming less common as the climate changes.
Albatross Divorce Doubles as Oceans Warm
Climate change is affecting ecosystems and species all over the world. For example, warmer temperatures are pushing pests further north, melting Arctic glaciers and bringing spring earlier. All of these factors can seriously impact food abundance and have already altered animal behavior.
Researchers wondered if climate was affecting albatross mating, so they checked back through research data gathered between 2004 and 2019 from an albatross colony in the South Atlantic Ocean situated on the Falkland Islands. The scientists found that climate change was indeed impacting the birds.
Normally, albatrosses mate for life. They return to the land after years at sea searching for food to breed and raise a single egg. Divorce among albatross pairs is rare, running at around 4% annually. A certain amount of albatross divorce is quite normal; usually it’s the female that leaves if the egg fails to hatch. She moves on to find another male and perhaps improve her breeding success.
However, when the researchers examined the population data, they found that divorce rates fluctuated in correlation with the temperature of the sea around the colony. As the ocean got warmer, not only did divorce rates almost double, but divorces were happening even in cases where chick rearing was successful.
Why Divorce Matters to Albatross Mating
Divorce increasing among normally stable and monogamous albatrosses impacts breeding success. A stable, longstanding relationship is vital for the shared duties of minding the nest and hatching the egg, and divorce takes each bird out of the action for a season.
For albatrosses and many other bird species, the breeding season requires careful timing and synchrony. Birds need to hit peak food abundance and optimal weather when there’s an egg in the nest. Moving on to another mate takes courtship, and as The Atlantic notes, putting additional effort into this behavior can often mean missing the breeding season.
Nature Canada reports that climate change is forcing birds to relocate to more hospitable environments as adverse weather changes conditions. Alterations in weather patterns and the onset of seasons have advanced breeding cycles, affected nesting and interfered with migration. Shifts in the timing of the breeding season due to climate change have also increased swallow chick mortality. Science Daily describes how albatrosses no longer choose to mate purely when food is widely available.
How Warmer Oceans Cool Albatross Mating
Although the study did not determine the exact reason for higher albatross divorce rates, warmer oceans mean less food, such as fish or squid. The Smithsonian Magazine suggests that, with decreased abundance, albatrosses have needed to spend more time out at sea looking for food. This would disrupt both the timing of their return to land for the breeding season and their physical condition. Prolonged hunting excursions also keep one parent away from the nest for longer, disrupting the egg hatching partnership.
Global warming doesn’t just affect albatross populations. For instance, the Yale Environment 360 magazine notes that warming also affects grassland species. Little bustards don’t take part in as many mating displays simply because it’s too hot, and they need to shelter from the heat. Scientific American even describes how climate change is driving bird promiscuity, leading to greater numbers of mate swaps. When environmental conditions get tough, it may be more than albatross mating that suffers.
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