Bird divorce a bad news, here’s why

Birds separating is not new, but it can also mean the environment around them is changing, writes Aisiri Amin.

While social monogamy has come under scrutiny for humans in recent times, about 90% of bird species live in monogamous pairs. But over the last few years, several studies have reported “bird divorces.” From the Seychelles warblers to the Great Tits, researchers have documented social behaviours that indicate pair separations.

Behavioural ecologist, specialising in the study of pair-bonding in birds, Dr Frigg Speelman, says divorce among birds refers to a disruption of the pair bond, in which two previously pair-bonded birds are no longer together but are both still alive.

"A pair bond is an exclusive social bond between two birds that reproduce together; they are 'socially monogamous'. Importantly, this is different from strict sexual monogamy since socially monogamous birds can still seek copulations with others, even when they are pair-bonded," she explains.

Over the years, rapid environmental changes and climate-change-driven global biodiversity loss have led to significant imbalances in the ecosystem. While the impact on bird populations has been studied, mating systems have not been widely explored. 

As reports of bird divorces are making headlines, a question has become unmissable: are these simply a matter of compatibility, or do environmental disruptions play a role?

Why are birds breaking up

Defining pair bonds and divorce among birds can be tricky. So researchers usually observe pairs over long periods, recording behaviours that signal a pair bond, Speelman elaborates. These include joint parental care, courtship behaviour, affiliative displays such as partner feeding and grooming, consistent physical proximity, and shared territories.

Bird divorce is not new. What has changed, and what is beginning to concern some experts, is why it is happening. 

In 2021, a study claimed to report the first evidence of how challenging environmental conditions disrupts breeding processes of a monogamous bird species. While breeding failure was a top reason for breakups among the albatrosses, which are among the world's most monogamous creatures, the researchers found that more albatrosses broke up when the sea was warmer than usual. The study also showed that females in a previously successful relationship are mostly affected by the environmental harshness. 

A more recent study, published in 2025, showed that environmental conditions prior to the breeding season appeared to affect mate faithfulness. The researchers found that wind speeds had the strongest impact on whether wild seabird couples stayed together.

The 2024 study, co-authored by Speelman, showed that divorce likelihood among the Seychelles warbler increased when there was either very little or too much rain.

Weather patterns may exacerbate factors linked to failed reproduction and to partners' perceived stress, Speelman says. For instance, it could lead to lower food availability and harsher ambient conditions. "In turn, this may misinform birds, leading them to divorce their partner in times of bad environmental conditions," she explains.

Climate change also exerts various local impacts on different habitats. It is changing local environmental conditions in ways that benefit certain species while harming others. "For instance, it is helping certain generalist bird species like Indian peafowl to colonise, while the specialist group of birds are going extinct," says Dr Jaydev Mandal, Assistant Professor, Department of Zoology, Madhab Choudhury College, Barpeta.

Mandal, involved in citizen science projects to understand the behaviour, distribution, and ecology of birds, explains that environmental changes are bound to affect how birds migrate, nest, and reproduce.

He gives the example of habitat specialist birds, such as those in the bustard family, the Great Indian Bustard, Bengal Florican, and Lesser Florican, which are all grassland species.

Grasslands are under tremendous pressure from succession (a slow process of change in the species composition in an area), invasion, and various other factors, Mandal explains. ”So these species are at risk of extinction, or they will shift to some other suitable environment. Within three to five decades, many of these species will go locally extinct from grassland patches that have degraded and can no longer be used for nesting or foraging," he says.

However, currently, studies do not explicitly confirm that climate change is directly linked to bird divorces. 

Bird divorces and ecosystem health

The State of the World's Birds 2022 report states that birds are "an excellent barometer for planetary health". Mandal calls them "very good bioindicators". By identifying the diversity of birds in a particular habitat, we can easily assess the condition of that environment, he adds.

"The change in pair-bonds also indicates a change in habitats and possibly how environmental changes are impacting biodiversity," Mandal explains.

At present, many factors contribute to environmental degradation and habitat loss, but Mandal highlights anthropogenic impacts as the primary driver. "Continuous changes in habitat caused by pollution, invasion, and many other human activities cannot be ignored. Beyond these, there are also natural factors such as ecological succession," he explains.

Research on animals' behavioural responses to climate change clearly shows that they can respond very strongly and quickly to climate disruptions. "This is a useful indicator but also a very alarming effect, as changes in reproductive behaviour such as increased divorce can have detrimental effects on entire populations and species over longer periods of time,” Speelman says. 

She points to a study on little penguins, in which divorce was a better indicator of population-level reproductive success than large-scale oceanographic indices, which are more typically used to predict the effects of climate change on seabird population dynamics.

Divorce is a double-edged sword. While it can help some birds escape poor-quality pair bonds and get a new partner, it can be detrimental if it happens after being misled by extreme weather patterns. “Probably species that are more vulnerable to climate change in general will be more at risk of climate-induced divorce, but for now, we do not know yet,” Speelman notes.

Mandal says more collaborative researches are needed, as current studies are sporadic and fragmented, conducted independently across the Western Ghats, Eastern Himalayas, and Eastern Ghats. "These efforts need to be scaled up and carried out in a more coordinated, collaborative manner," he says.