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I'm tired and don't love anymore.
Written by |Huang Yujia.
Proofreading |Wang Yibo.
In addition to humans, many animals also opt for "monogamy", i.e., monogamy. For example, this is true for 90% of birds, who will only mate with one mate in their lifetime or during a breeding season.
For long-lived seabirds, there are many benefits to being loyal to one mate. On the one hand, it will be easier to breed with a familiar partner, because based on previous experience, the "couple" can raise babies more tacitly;On the other hand, these seabirds have a higher natural survival rate, they are less likely to suddenly become "widows", and attracting new mates means additional time and effort costs, but not necessarily higher returns.
However, although they are all "monogamous", different species have different levels of fidelity to their mates. Even in species that are usually loyal to their partners, some of them are more likely to be "divorced". And even individuals who are not easily "divorced" may suddenly "divorce" under some special circumstances.
It's all for the kids.
Scientists generally believe that if a seabird that rarely "divorces" ends up breaking down, the main cause is breeding failure. "Divorce" allows them to get rid of unsuitable partners and increase the probability of successful reproduction.
Fran Ois Guerraz, CC BY-SA 30, via wikimedia commons）
In the case of the Black-browed Albatross (), in the Malvinas Islands, female black-browed albatross who have not even hatched their eggs are most likely to be "divorced", with only an 11% chance of maintaining their original mate. Females that successfully hatch eggs but fail to raise chicks have an 87% chance of maintaining their mates. As for the mothers who have successfully bred their offspring, they are the happiest and most enviable, and they are the most likely to continue to maintain their original mate – 97%.
The researchers found that for the black-browed albatross group, the "divorce" and "remarriage" of the female birds does seem to make raising a baby easier, but only a little easier. The success rate of these females before the "divorce" was only 65%, but after the "remarriage" the probability of breeding reached 69%. It can be seen that "divorce" is a decision made by female birds after breeding failure, and they want to find a more suitable partner.
But for the black-browed albatross individual, the happy birds are all similar, and the unfortunate birds have their own misfortunes. This is the case with male black-browed albatross that have experienced a "divorce" after a failed rearing, and even if they have a new mate, they still struggle to successfully reproduce. The data shows that the male birds "remarried" and successfully raised offspring only 26 percent of the time, while the female birds who experienced the same experience had a 47 percent success rate. Male black-browed albatross is less likely to find a new partner after "divorce", and as a result, he has not been able to increase the fertility rate through "remarriage", which is very lonely.
The fertility success rate of black-browed albatross with or without changing partners (**original**) of previously successful (s), failed (f), nonb, or widowed (wid).
Don't be for the faint of heart.
There are many factors that affect the reproductive success of seabirds, and the characteristics of seabirds themselves are one of them.
The three-toed gull () is a long-lived monogamous seabird that usually lives to be over 25 years old. Once the male and female three-toed gulls are "husband and wife", they begin to raise their offspring together. In Svalbard, Norway, the beginning of June is the incubation period for the three-toed gull. Each couple will take care of 1 or 2 chicks, and this co-breeding process will continue until late July or even early August. After the breeding season is over, they separate and live separately at sea until the next breeding season arrives, when they meet again and reproduce.
Different three-toed gulls have different personalities. In general, bold individuals have a stronger risk tolerance, while shy individuals tend to make more conservative choices due to their fear of risk. So when you see something new, such as a blue plastic toy penguin, those bold three-toed gulls seem to be casual and very calm. On the contrary, the timid three-toed gull will be frightened and flutter away.
The bold three-toed gull (**original**).
Researchers have found that personality influences the preference of three-toed gulls when looking for a mate. In two locations in Svalbard, the preference of the three-toed gull varies depending on the population. The male three-toed gull in one place is more inclined to seek out a mate who is close to his guts, while the male three-toed gull in the other area prefers the timid female.
The results showed that the greater the personality differences between the three-toed gull mates, the more likely they were to have reproductive failure, which increased the likelihood that they would choose to "divorce" and find a new mate in the following year. At this time, these "divorced" single birds will also be more inclined to choose a partner with a similar personality to themselves, and will no longer be as impulsive as before.
Researchers believe that the proximity of personalities may make the three-toed gull mate more compatible, make similar decisions when faced with a choice, understand each other better, and be better able to nurse their offspring. Therefore, those three-toed gulls after the "divorce" will correct the mistakes made in the last mate selection. However, unlike the male black-browed albatross, which is very injured after the "divorce", the "divorce" and "remarriage" do not seem to affect the breeding of the three-toed gull.
It's hot, it's tired.
In addition to the factors of the seabirds themselves, such as personality and reproductive ability, the external environment will also affect their "divorce" rate. The researchers found that between 2004 and 2019, the annual "divorce" rate of black-browed albatross fluctuated widely, from 08% to 77% ranged. After comparing with the sea surface temperature data, the results showed that the annual "divorce" rate of the black-browed albatross was significantly positively correlated with the abnormal increase of sea surface temperature.
In years when the sea surface temperature is abnormally high, the "divorce" rate and "divorce" probability will increase for both black-browed albatross groups and individuals. Even when reproductive failure is taken into account, a 1 increase in the standard deviation of sea surface temperature anomalies is associated with a further 1% increase in the rate of "divorce".
Researchers believe that the anomalously high sea surface temperature has had a negative impact on ocean productivity. Phytoplankton, benthic plants, and the various animals that feed on these autotrophs have all been affected. Such a bottom-up process results in less food for black-browed albatrosses, making it more costly and harder to breed.
a) the "divorce" rate of black-browed albatross between 2004 and 2019;(b) Effect of SSTA on the "divorce" rate of black-browed albatrosses. (*original**).
Under such difficult conditions, seabirds may delay their breeding period, or they may be in a reproductive period but not in a good physiological state;For migratory species, environmental changes can also lead to seabird "couples" not being able to reach their breeding sites at the same time, and a good "marriage" eventually has to end in "divorce";In more severe cases, environmental changes may directly lead to the death of individual seabirds.
Under the influence of many aspects, even if the female black-browed albatross fails to reproduce due to her own reasons, physiological pressure may still cause them to "dump" the pot to the male bird, and then ask for "divorce". Studies have shown that females who have poor relationships and unhappy mates do have higher levels of corticosterone, a stress-related hormone. The harsh environment and food shortages do lead to increased corticosterone concentrations in seabirds, so they are likely to find a partner due to stress during periods of abnormally high sea surface temperatures.
Reference Links: *The content represents the author's views only.
It does not represent the position of the Institute of Physics of the Chinese Academy of Sciences.
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*: Global Science.
Editor: Lan Duoduo.