Is climate change happening too fast for birds to keep up?

Since evolution is usually a slow process, many animal species have significant problems adapting to a rapidly changing climate. 

To estimate the possible impacts of climate change on birds, a team of scientists led by the Netherlands Institute of Ecology (NIOO-KNAW) has recently conducted a genomic selection experiment on great tits (Parus major), a model species frequently used in scientific studies. The research is published in the journal Science Advances. 

Studying how birds change by examining the future

“It’s important to know [how fast species can adapt to climate change] because climate change and evolution need to keep a relatively even pace for species to keep up,” said senior author Marcel Visser, a biologist at NIOO-KNAW.

“That’s why we set out to study great tits from the future. In the coming decades, natural selection will produce birds with a particular genetic make-up. To predict the extent to which these birds can respond to natural selection, we sped up evolution through artificial selection of genetically early and late birds in aviaries. We then took the eggs to our long-term population in De Hoge Veluwe national park, to see how their offspring did compared to wild great tits.”

“In the forest, the earliest birds did in fact lay their eggs earlier than great tits selected for laying eggs late,” reported lead author Melania Lindner, a doctoral student in Ornithology at the same institution. 

“So we were able to successfully select them for laying eggs early or late in spring. But the earliest birds didn’t lay their eggs significantly earlier than the wild great tits breeding in the forest, while the ones we selected for laying their eggs late, did have a significantly later lay date.”

Thus, the early birds did not seem to breed more successfully than their wild counterparts, suggesting that genetic adaptation towards early lay dates is an extremely slow process.

Climate change is happening too fast for animal evolution

Moreover, climate change will likely cause significant ecological relationship problems to insectivorous songbirds such as the great tit.

According to the experts, their timing no longer matches that of the insects their offspring need to feed on, such as caterpillars, making the young miss out sources of nutrients that usually play a major role in their growth. 

While changing their timing could be a possible solution, it is not yet clear how much earlier the birds could actually lay their eggs.

“What we’re seeing now is that climate change is simply going too fast for them,” Visser said. “They won’t be able to adapt sufficiently. In the bleakest climate scenarios, in particular, the birds will fall behind more and more.”

Climate impacts on animal evolution are camouflaged

However, for the moment, the real impact of climate change on great tits is “camouflaged” by density-dependent processes.

For instance, since out of every ten chicks, eight or nine would usually die in their first year due to factors such as predation, food shortages, or competition, if three of them die before fledging due to climate change, the chances of the remaining seven may improve. 

Moreover, there is also significant annual weather variation, which makes it more difficult to measure the impact of climate on the birds in the field.

Although the mismatch between wild great tits and their food was surprisingly small during the study period, this situation is likely to change as the climate continues to warm.

 “Now that we have looked at the impact of climate change on the relatively straightforward food chain of oak tree, winter moth, and great tit, it’s time to see if we can include a larger number of the species that together make up a food network,” Visser concluded.

More about birds and climate change

Birds are greatly affected by climate change, which has been primarily driven by human activities such as the burning of fossil fuels, deforestation, and industrial processes. Here are some of the key ways in which climate change affects bird populations:

Habitat shifts

As temperatures rise, the habitats of many bird species are shifting. For instance, birds that typically live in cooler climates may move further north or to higher elevations. This can cause displacement, and in some cases, the birds might not find suitable new habitats, leading to population declines.

Birds change migration patterns

Many birds rely on specific cues for migration, such as temperature and the availability of food. Climate change can cause these cues to change, which can, in turn, affect the timing and patterns of bird migration. This might lead to mismatches between the time when birds migrate and the availability of food and nesting sites.

Changes in food availability

Climate change can affect the abundance and distribution of prey and plant species that birds rely on for food. For example, if insects emerge earlier in the year due to warmer temperatures but birds do not adjust their migration patterns accordingly, there may be less food available for the birds when they arrive at their breeding grounds.

Extreme weather events

An increase in the frequency and severity of storms, droughts, and other extreme weather events can have devastating effects on bird populations. For example, intense hurricanes can destroy nesting sites, while droughts can reduce the availability of water and food.

Sea level rise

Many bird species live in coastal areas, and rising sea levels due to the melting of polar ice caps can result in the loss of critical habitats for these birds. Species that nest on beaches or in marshes are particularly vulnerable.

Altered breeding seasons

Warmer temperatures may cause birds to begin their breeding seasons earlier. This can sometimes be beneficial if it allows them to take advantage of more abundant food resources, but it can also lead to problems if, for instance, the young birds are not yet strong enough to survive when it is time for them to migrate.

Increased disease and parasites

Warmer temperatures can also lead to the spread of diseases and parasites that affect bird populations. For example, as temperatures rise, mosquitoes, which are vectors for diseases like West Nile Virus, can expand their range, potentially affecting bird populations not previously exposed to these diseases.

Species interactions and competition

As bird species move and adapt to new areas, they may come into contact and compete with other species they didn’t encounter before. This can have unpredictable consequences on community structures and the survival of some species.

Conservation efforts aimed at mitigating the effects of climate change on bird populations are important. These can include protecting and restoring habitats, creating corridors for species migration, and taking measures to reduce greenhouse gas emissions that contribute to climate change. 

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By Andrei Ionescu, Earth.com Staff Writer

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