Nav: Home

Climate change intensifies war of the birds

January 10, 2019

University of Groningen (UG) biologists have discovered that climate change has an effect on the regular clashes between great tits and pied flycatchers during the breeding season. In some years, great tits killed 10% of the male pied flycatchers. UG researchers have published an analysis of this behaviour on 10 January in the journal Current Biology.

Great tits are not just the funny, fluffy birds feeding off the fat balls in your winter garden. 'During the breeding season, they can become very aggressive indeed', says biologist Jelmer Samplonius. He studied great tits and pied flycatchers for his Ph.D. thesis at the University of Groningen.

Aggression

While checking the nest boxes used in his field studies, Samplonius would regularly find the results of this aggression: a dead flycatcher in a nest box occupied by great tits. 'When a flycatcher enters a box with a great tit inside, it doesn't stand a chance', Samplonius explains. 'The great tit is heavier, as the flycatchers are built for a long migration from Europe to Western Africa and back. Also, great tits have very strong claws.' In this case, the dead flycatchers usually have fatal head wounds. 'And it appears that the great tits then eat the brains.'

There has always been competition between the two species for nesting locations. 'Pied flycatchers try to steal nesting facilities from the tits. They may be no match when fighting inside the nesting boxes, but they are more agile flyers', says Samplonius. Flycatchers fly around the great tits while they are building their nests, thus driving them away.

Adaptation

The question that Samplonius and his Ph.D. supervisor Christiaan Both tackled in the Current Biology paper is whether climate change has any effect on this behaviour. 'Both species need to time the birth of their young with a peak in the availability of caterpillars', says Samplonius. This peak is linked to the appearance of the first leaves on trees, and higher average temperatures mean that this period has shifted to earlier in the year.

Great tits are non-migratory birds, and they respond to higher temperatures by laying their eggs earlier. 'Pied flycatchers now migrate to Europe earlier, but their adaptation is not as good as that of the great tits. Their earlier arrival is not linked to the actual temperature at their breeding grounds.' Samplonius knows this because, over a period of 10 years, he and his colleagues have recorded the arrival of pied flycatchers and the start of egg laying of both great tits and flycatchers in two national parks.

Mortality

Milder winters are one result of climate change. 'This increases the survival of great tits, so the number of breeding birds will be higher.' More great tits mean more competition for the flycatchers - and more conflict. It should be noted, however, that climate change is not the only factor in this: mast years - years in which there are more beechnuts - also increase great tit survival.

A second reason for the increased competition is that great tits and pied flycatchers have adapted to climate change differently. The biggest problems occur in colder springs, when tits start building their nests relatively late but the flycatchers still arrive early. 'In this situation, the overlap in breeding time is greatest, and so is the number of conflicts.' Great tits killed up to 10% of territorial male flycatchers inside a nesting box in just two weeks of competition. As the mortality for flycatchers across the entire year is about 55%, this is quite a lot.

Climate change

Interestingly, we didn't see an effect on the overall flycatcher population of about 300 breeding pairs in our study', remarks Samplonius. 'We noted that the males killed were usually those who arrived late in the season. These late birds quite often don't find a female to breed with, so that may explain why this behaviour has no impact on the population.'

Overall, the study shows that climate change affects the behaviour of both bird species, as well as the interaction between them. A group led by Christiaan Both, Professor of Ecology at the Groningen Institute for Evolutionary Life Sciences (GELIFES), will continue to study tits and flycatchers to discover if there are any long-term effects of this behaviour. Samplonius, meanwhile, has moved to the University of Edinburgh, where he is now studying blue tits. 'I'm looking at similar questions here, along a 220-kilometer transect in Scotland. It's really interesting to witness all these changes caused by climate change.'
-end-
Reference: J.M. Samplonius and C. Both: Climate Change May Affect Fatal Competition between Two Bird Species. Current Biology 10 January 2019.

University of Groningen

Related Climate Change Articles:

The black forest and climate change
Silver and Douglas firs could replace Norway spruce in the long run due to their greater resistance to droughts.
For some US counties, climate change will be particularly costly
A highly granular assessment of the impacts of climate change on the US economy suggests that each 1°Celsius increase in temperature will cost 1.2 percent of the country's gross domestic product, on average.
Climate change label leads to climate science acceptance
A new Cornell University study finds that labels matter when it comes to acceptance of climate science.
Was that climate change?
A new four-step 'framework' aims to test the contribution of climate change to record-setting extreme weather events.
It's more than just climate change
Accurately modeling climate change and interactive human factors -- including inequality, consumption, and population -- is essential for the effective science-based policies and measures needed to benefit and sustain current and future generations.
Climate change scientists should think more about sex
Climate change can have a different impact on male and female fish, shellfish and other marine animals, with widespread implications for the future of marine life and the production of seafood.
Climate change prompts Alaska fish to change breeding behavior
A new University of Washington study finds that one of Alaska's most abundant freshwater fish species is altering its breeding patterns in response to climate change, which could impact the ecology of northern lakes that already acutely feel the effects of a changing climate.
Uncertainties related to climate engineering limit its use in curbing climate change
Climate engineering refers to the systematic, large-scale modification of the environment using various climate intervention techniques.
Public holds polarized views about climate change and trust in climate scientists
There are gaping divisions in Americans' views across every dimension of the climate debate, including causes and cures for climate change and trust in climate scientists and their research, according to a new Pew Research Center survey.
The psychology behind climate change denial
In a new thesis in psychology, Kirsti Jylhä at Uppsala University has studied the psychology behind climate change denial.

Related Climate Change Reading:

Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming
by Paul Hawken (Editor), Tom Steyer (Editor)

The Thinking Person's Guide to Climate Change
by Robert Henson (Author)

The Sixth Extinction: An Unnatural History
by Elizabeth Kolbert (Author)

Climate Change: What Everyone Needs to Know®
by Joseph Romm (Author)

Introduction to Modern Climate Change
by Andrew Dessler (Author)

This Changes Everything: Capitalism vs. The Climate
by Naomi Klein (Author)

Global Climate Change: Turning Knowledge Into Action
by David E. Kitchen (Author)

Climate Change: What Everyone Needs to Know®
by Joseph Romm (Author)

Climate Change: The Facts 2017
by Jennifer Marohasy (Editor)

Global Warming: Understanding the Forecast
by David Archer (Author)

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Approaching With Kindness
We often forget to say the words "thank you." But can those two words change how you — and those around you — look at the world? This hour, TED speakers on the power of gratitude and appreciation. Guests include author AJ Jacobs, author and former baseball player Mike Robbins, Dr. Laura Trice, Professor of Management Christine Porath, and former Danish politician Özlem Cekic.
Now Playing: Science for the People

#509 Anisogamy: The Beginning of Male and Female
This week we discuss how the sperm and egg came to be, and how a difference of reproductive interest has led to sexual conflict in bed bugs. We'll be speaking with Dr. Geoff Parker, an evolutionary biologist credited with developing a theory to explain the evolution of two sexes, about anisogamy, sexual reproduction through the fusion of two different gametes: the egg and the sperm. Then we'll speak with Dr. Roberto Pereira, research scientist in urban entomology at the University of Florida, about traumatic insemination in bed bugs.