Posted: Nov 26, 2021 01:07 GMT
A study found factors that promote the separation of couples of this type of bird, considered by scientists as the most constant in their relationships.
Climate change and ocean warming negatively affect the life of albatrosses and possibly is at the origin of the breakup of many pairs of these large seabirds, according to a study published Wednesday in the journal Proceedings of The Royal Society B.
The increase in water temperature results in a decline in fish population, which forces the birds to spend more time away from the coast to obtain food. These more severe conditions can affect hormone levels and reduce the chance of survival of the offspring, the authors estimate.
Although albatrosses are monogamous birds with very stable pairs, warming appears to “indirectly affect their separation through changes in population rates.” In particular, the tendency to ‘divorce’ may be linked to “higher reproductive costs, changes in phenology (the relationship between climatic factors and life cycles) and physiological stress,” the study details.
The team of ornithologists led by Francesco Ventura has been the first to document “disruptive effects of challenging environmental conditions” that have allowed them to conclude that these birds separate more often in years with temperature abnormalities on the surface of the sea.
The birds of the Falklands in figures
“The environmentally driven breakdown may, therefore, be an inadvertent consequence of global change”, synthesizes the scientific article. To reach this conclusion, the researchers looked at a wild population of 15,500 pairs black-browed albatross (Thalassarche melanophris) that nested in the Falkland Islands for 15 years. Although a stress phenomenon or an environmental event such as a storm can cause deaths, the study excluded cases of separation in which a member of the couple died.
The team determined that the annual average of separations was 3.7%, which could range between 0.8% and 7.7% depending on different external factors. Something that was already known is that pairs were statistically more likely to separate after failed reproduction (loss of the egg or chick). Even taking these individual failures and fish shortages into account, the likelihood of divorce grew those years in which the sea surface warmed more. Thus, in 2017, when water surface temperatures were unusually high, the ‘divorce’ rate skyrocketed by almost 8%.
Stress and ‘guilt’ of them and of them
As Ventura pointed out in statements to The Guardian newspaper, the increase in the separation rate of these birds could be due to the fact that climate change increases stress in relationships between albatrosses. “We propose the hypothesis of guilt in the couple” in reference to a situation in which the female could feel “higher levels of stress” and attribute them to “poor performance” of the male.
The researchers also concluded that males are less likely to initiate separation than females, because they were more likely to procreate with a new partner than they, which is a characteristic trait for this family of birds.
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