By Marlene Cimons
Most Europeans know the great tit as an adorable, likeable yellow-and-black songbird that shows up to their feeders in the winter. But there may be one thing they don't know. That cute, fluffy bird can be a relentless killer.
The great tit's aggression can emerge in gruesome ways when it feels threatened by the pied flycatcher, a bird that spends most of the year in Africa, but migrates to Europe in the spring to breed. When flycatchers arrive at their European breeding grounds, they head for great tit territory, knowing that great tits—being year-round European residents—know the best nesting sites.
"They want to breed at a high-quality site, so taking over a great tit nest is an ideal shortcut to a high-quality breeding site," said biologist Jelmer Samplonius, a researcher at the University of Edinburgh who studied their interactions for his doctoral thesis at the University of Groningen. "However, this can go horribly wrong, because if the great tit is home, or comes home while the pied flycatcher tries to take over, the pied flycatcher will pay dearly—with its life in some cases."
Usually, flycatchers breed a couple of weeks after great tits, but lately, nasty clashes between these natural enemies are accelerating, because of an overlap in their breeding periods due to climate change.
Jelmer Samplonius holds a pied flycatcher. Rob Buiter / Current Biology
Pied flycatchers produce offspring when there is an abundance of caterpillars, their preferred food. Caterpillars are most bountiful when the first leaves appear on trees, and trees are leafing sooner because climate change is causing spring to arrive earlier. This, in turn, has led flycatchers to migrate sooner, arriving while the great tits are hanging around. At the same time, climate change has produced milder winters, allowing more tits to survive until spring. The greater number of tits is giving rise to more potential murders, as "more great tits means more competition for the flycatchers," Samplonius said.
Scientists saw "huge differences" in the number of victims over the years. In some years, nearly 10 percent of the flycatcher males died in great tit nests, while, in other years, there were none. "We found that, in areas and years with high tit densities, after warmer winters there were more flycatcher victims," he said.
Across the board, climate change has been causing shifts in the migratory patterns of many species, threatening their ability to feed and nurture their offspring. Rising temperatures are also limiting the growth and development of young birds, with some species shrinking in size. Samplonius's study, published recently in the journal Current Biology, suggests it also is causing more competition for resources—and a higher body count.
While checking the great tit nest boxes used in his field studies, Samplonius found numerous dead flycatchers, suggesting they were trying to take over the territory. Although flycatchers—built for long distance travel—are more agile flyers, "when a flycatcher enters a box with a great tit inside, it doesn't stand a chance, as great tits are heavier [and] have very strong claws," he said.
The interaction can be quite ugly, as the tits also occasionally inflict grisly head wounds and then eat their victims' brains. But like flycatchers, they'd rather eat caterpillars. "We consider the brain-eating more a by-product of the aggressive interactions," Samplonius said. "In general, great tits are insectivorous."
During the breeding season specifically, most of their food consists of caterpillars, although they are only available for a short period during spring. When insects become scarce, great tits switch to beech nuts. "However, this does not mean great tits do not eat other, bigger animals," Samplonius said. "They are known to hunt bats occasionally, and also smaller birds in winter. However, we still consider this to be relatively rare behavior."
A great tit preys on a pied flycatcher. Maurice van Laar / Current Biology
Notably, scientists found that conflicts with great tits had no effect on the overall flycatcher population. "We noted that the males killed were usually those who arrived late in the season," he said. "These late birds quite often don't find a female to breed with, so that may explain why this behavior has no impact on the population."
Michael McGrann, a bird researcher who chairs William Jessup University's institute for biodiversity—who was not involved in the study—said the findings didn't surprise him. Scientists, he said, have been worried that changing weather patterns "will cause residents and long-distance migrants to differ in how they shift their geographic ranges, and in how they adjust the seasonal timing of the onset of breeding behaviors," resulting in potential conflicts between species.
Wildlife ecologist Brett Furnas, senior environmental scientist in the California Department of Fish and Wildlife's wildlife investigations laboratory, who was also not involved in the study, agreed. The study is "a great example of how the impacts of climate change will be complex and sometimes difficult to predict, because not all species will be affected the same way or at the same rate," he said. "It demonstrates how species are changing their behavior and interactions with each other in response to a changing climate. A better understanding of how some species benefit and others suffer can help us plan effective conservation efforts."
Simon Griffith, an avian scientist in Macquarie University's department of biologist sciences in Sydney, who also not involved in the study, lamented the death of migrating flycatchers. "It's both amazing and sad to think that these tiny flycatchers have migrated all the way [from] Africa back to Europe, ready to breed, to then succumb to the challenge of a great tit that has spent the winter in Europe, enduring the cold conditions there," he said.
Samplonius pointed out that the tit and the flycatcher likely are susceptible to the same instincts that drive other forces in nature, including people. "We know that in humans, climate change is considered a catalyst of conflict," he said. "Our study shows this may also be the case in birds."
40% of the world's 11,000 bird species are in decline: "One in Eight Bird Species Threatened With Extinction, Study… https://t.co/CpVepHzDET— Enviro. Media Assoc. (@Enviro. Media Assoc.)1524515238.0
Reposted with permission from our media associate Nexus Media.
- 52 Percent of World's Birds of Prey Populations in Decline - EcoWatch ›
- 'Fish Fights' Could Erupt as Climate Change Drives Species Across ... ›
Yet another former Trump administration staffer has come out with an endorsement for former Vice President Joe Biden, this time in response to President Donald Trump's handling of the coronavirus pandemic.
- Trump Denies CDC Director's 2021 Timeline for Coronavirus Vaccine ›
- Trump Orders Hospitals to Stop Sending COVID-19 Data to CDC ... ›
- Two White House Staffers Test Positive for Coronavirus - EcoWatch ›
- Trump Admin to Disband Coronavirus Task Force - EcoWatch ›
- Pence Offers 'Prayers' as Hurricane Laura Hits Gulf Coast While ›
EcoWatch Daily Newsletter
Every September for the past 11 years, non-profit the Climate Group has hosted Climate Week NYC, a chance for business, government, activist and community leaders to come together and discuss solutions to the climate crisis.
- Covering the 2020 Elections as a Climate Story - EcoWatch ›
- Coronavirus Delays 2020 Earth Overshoot Day by Three Weeks ... ›
By Elliot Douglas
The coronavirus pandemic has altered economic priorities for governments around the world. But as wildfires tear up the west coast of the United States and Europe reels after one of its hottest summers on record, tackling climate change remains at the forefront of economic policy.
- German Business Leaders Call for Climate Action With COVID-19 ... ›
- Climate Activists Protest Germany's New Datteln 4 Coal Power Plant ... ›
By D. André Green II
One of nature's epic events is underway: Monarch butterflies' fall migration. Departing from all across the United States and Canada, the butterflies travel up to 2,500 miles to cluster at the same locations in Mexico or along the Pacific Coast where their great-grandparents spent the previous winter.
Millions of People Care About Monarchs<p>I will never forget the sights and sounds the first time I visited monarchs' overwintering sites in Mexico. Our guide pointed in the distance to what looked like hanging branches covered with dead leaves. But then I saw the leaves flash orange every so often, revealing what were actually thousands of tightly packed butterflies. The monarchs made their most striking sounds in the Sun, when they burst from the trees in massive fluttering plumes or landed on the ground in the tussle of mating.</p><p>Decades of educational outreach by teachers, researchers and hobbyists has cultivated a generation of monarch admirers who want to help preserve this phenomenon. This global network has helped restore not only monarchs' summer breeding habitat by planting milkweed, but also general pollinator habitat by planting nectaring flowers across North America.</p><p>Scientists have calculated that restoring the monarch population to a stable level of about 120 million butterflies will require <a href="https://doi.org/10.1111/icad.12198" target="_blank">planting 1.6 billion new milkweed stems</a>. And they need them fast. This is too large a target to achieve through grassroots efforts alone. A <a href="https://www.fws.gov/savethemonarch/CCAA.html" target="_blank" rel="noopener noreferrer">new plan</a>, announced in the spring of 2020, is designed to help fill the gap.</p>
Pros and Cons of Regulation<p>The top-down strategy for saving monarchs gained energy in 2014, when the U.S. Fish and Wildlife Service <a href="https://www.fws.gov/southeast/pdf/petition/monarch.pdf" target="_blank">proposed</a> listing them as threatened under the Endangered Species Act. A decision is expected in December 2020.</p><p>Listing a species as endangered or threatened <a href="https://www.fws.gov/endangered/esa-library/pdf/listing.pdf" target="_blank">triggers restrictions</a> on "taking" (hunting, collecting or killing), transporting or selling it, and on activities that negatively affect its habitat. Listing monarchs would impose restrictions on landowners in areas where monarchs are found, over vast swaths of land in the U.S.</p><p>In my opinion, this is not a reason to avoid a listing. However, a "threatened" listing might inadvertently threaten one of the best conservation tools that we have: public education.</p><p>It would severely restrict common practices, such as rearing monarchs in classrooms and back yards, as well as scientific research. Anyone who wants to take monarchs and milkweed for these purposes would have to apply for special permits. But these efforts have had a multigenerational educational impact, and they should be protected. Few public campaigns have been more successful at raising awareness of conservation issues.</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="91165203d4ec0efc30e4632a00fdf57d"><iframe lazy-loadable="true" src="https://www.youtube.com/embed/KilPRvjbMrA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
The Rescue Attempt<p>To preempt the need for this kind of regulation, the U.S. Fish and Wildlife Service approved a <a href="https://www.fws.gov/savethemonarch/pdfs/Monarch%20CCAA-CCA%20Public%20Comment%20Documents/Monarch-Nationwide_CCAA-CCA_Draft.pdf" target="_blank">Nationwide Candidate Conservation Agreement for Monarch Butterflies</a>. Under this plan, "rights-of-way" landowners – energy and transportation companies and private owners – commit to restoring and creating millions of acres of pollinator habitat that have been decimated by land development and herbicide use in the past half-century.</p><p>The agreement was spearheaded by the <a href="http://rightofway.erc.uic.edu/" target="_blank">Rights-of-Way Habitat Working Group</a>, a collaboration between the University of Illinois Chicago's <a href="https://erc.uic.edu/" target="_blank" rel="noopener noreferrer">Energy Resources Center</a>, the Fish and Wildlife Service and over 40 organizations from the energy and transportation sectors. These sectors control "rights-of-way" corridors such as lands near power lines, oil pipelines, railroad tracks and interstates, all valuable to monarch habitat restoration.</p><p>Under the plan, partners voluntarily agree to commit a percentage of their land to host protected monarch habitat. In exchange, general operations on their land that might directly harm monarchs or destroy milkweed will not be subject to the enhanced regulation of the Endangered Species Act – protection that would last for 25 years if monarchs are listed as threatened. The agreement is expected to create up to 2.3 million acres of new protected habitat, which ideally would avoid the need for a "threatened" listing.</p>
A Model for Collaboration<p>This agreement could be one of the few specific interventions that is big enough to allow researchers to quantify its impact on the size of the monarch population. Even if the agreement produces only 20% of its 2.3 million acre goal, this would still yield nearly half a million acres of new protected habitat. This would provide a powerful test of the role of declining breeding and nectaring habitat compared to other challenges to monarchs, such as climate change or pollution.</p><p>Scientists hope that data from this agreement will be made publicly available, like projects in the <a href="https://www.fws.gov/savethemonarch/MCD.html" target="_blank">Monarch Conservation Database</a>, which has tracked smaller on-the-ground conservation efforts since 2014. With this information we can continue to develop powerful new models with better accuracy for determining how different habitat factors, such as the number of milkweed stems or nectaring flowers on a landscape scale, affect the monarch population.</p><p>North America's monarch butterfly migration is one of the most awe-inspiring feats in the natural world. If this rescue plan succeeds, it could become a model for bridging different interests to achieve a common conservation goal.</p>
The annual Ig Nobel prizes were awarded Thursday by the science humor magazine Annals of Improbable Research for scientific experiments that seem somewhat absurd, but are also thought-provoking. This was the 30th year the awards have been presented, but the first time they were not presented at Harvard University. Instead, they were delivered in a 75-minute pre-recorded ceremony.