No More Road Kill - Evolution Helped Swallows Avoid Car Crashes

Cliff swallows (not European or African swallows...) nesting under a bridge in New Jersey, USA
Cliff swallows (not European or African swallows...) nesting under a bridge in New Jersey, USA
Pia Heinemann

BERLIN - How fast is evolution? Pretty fast, according to a recent study by researchers at the University of Tulsa published in the scientific journal Current Biology.

An estimated 80 million birds are killed by cars each year. In Europe too, millions of birds die the same way.

But over the past 30 years, the number of cliff swallows (Petrochelidon pyrrhonota) killed by cars in southwestern Nebraska has shrunk significantly, according to Charles R. Brown and Mary Bomberger Brown. The two researchers have been studying the birds since the 1980s and published their findings in a paper entitled “Where has all the road kill gone?”

In southwestern Nebraska, cliff swallows nest in large colonies under highway bridges and overpasses. In the past that meant that they often flew into cars. During their observations, the researchers noted that this was happening less and less frequently and looked into possible reasons behind the phenomenon.

Nests of South African swallows under a bridge - Photo: NJR ZA

They couldn’t substantiate the most obvious causes. During the time frame, traffic had not decreased. In fact the Browns recorded an increase in larger vehicles such as SUVs, so that – because of the larger surfaces of such vehicles – the danger for the birds actually went up. They thus excluded more favorable traffic conditions as a cause for the lower road kill rates.

The global number of birds did not decrease either – on the contrary, the birds apparently enjoyed developing their highway nesting area.

Examinations of swallows that had been killed by cars showed that they generally had a larger wingspan than other swallows in the colony. According to the researchers, birds with the wider wingspan have a tougher time avoiding oncoming cars than those with a shorter wingspan, which allows the bird to turn more quickly.

Not keeping all the eggs in one basket

“One possible explanation is that selection has favored individuals whose wing morphology allows for better escape,” says the paper: “Longer wings have lower wing loading and do not allow as vertical a takeoff as shorter, more rounded wings. Thus, individuals sitting on a road, as cliff swallows often do, who are able to fly upward more vertically may be better able to avoid or more effectively pivot away from an oncoming vehicle.”

Photo: HarmonyonPlanetEarth

Over the decades, natural selection has favored birds with shorter wings. Since they don’t die as frequently in collisions they have more reproductive success than longer-winged swallows.

“Other explanations for the reduction in road kill are that swallows may learn to avoid collisions as they encounter a vehicle themselves or observe other birds flying away from vehicles or getting hit, or that risk-taking individuals have been selectively removed," says the study.

"Regardless of mechanism, the drop in traffic-related mortality over 30 years suggests that researchers should consider the possibility that road mortality in other species may change temporally and exert selection,” the researchers write. Good news for researchers whose research subjects are often the victims of traffic accidents.

Cliff swallows are also interesting to scientists for other reasons – they have a relatively novel way to insure the survival of their offspring. Female cliff swallows initially lay all their eggs in one nest. After some time has elapsed they take one of the eggs and transport it to the nest of another female. This egg is a form of “insurance” so that if their own nest is destroyed, chances are great that their genes live on in at least one chick.

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Migrant Lives

The Other Scandal At The Poland-Belarus Border: Where's The UN?

The United Nations, UNICEF, Red Cross and other international humanitarian organizations seems to be trying to reach the Polish-Belarusian border, where Belarus leader Alexander Lukashenko is creating a refugee crisis on purpose.

Migrants in Michalowo, Belarus, next to the border with Poland.

Wojciech Czuchnowski

WARSAW — There is no doubt that the refugees crossing the Belarusian border with Poland — and by extension reaching the European Union — were shepherded through by the regime of Alexander Lukashenko. There is more than enough evidence that this is an organized action of the dictator using a network of intermediaries stretching from Africa and the Middle East. But that is not all.

The Belarusian regime has made no secret that its services are guiding refugees to the Polish border, literally pushing them onto (and often, through) the wires.

It can be seen in films made available to the media by... Belarusian border guards and Lukashenko's official information agencies.

Tactics of a strongman

Refugees are not led to the border by "pretend soldiers" in uniforms from a military collectibles store. These are regular formations commanded by state authorities. Their actions violate all rules of peaceful coexistence and humanitarianism to which Belarus has committed itself as a state.

Belarus is dismissed by the "rest of the world" as a hopeless case of a bizarre (although, in the last year, increasingly brutal) dictatorship. But it still formally belongs to a whole range of organizations whose principles it violates every day on the border with Poland.

Indeed, Belarus is a part of the United Nations (it is even listed as a founding state in its declaration), it belongs to the UNICEF, to the International Committee of the Red Cross, and even to the Organization for Security and Cooperation in Europe (OSCE).

Photo of Polish soldiers setting up a barbed wire fence in the Border Zone near Krynki, Belarus

Polish soldiers set up a barbed wire fence in the Border Zone near Krynki, Belarus

Maciej Luczniewski/ZUMA

Lukashenko would never challenge the Red Cross

Each of these entities has specialized bureaus whose task is to intervene wherever conventions and human rights are violated. Each of these organizations should have sent their observers and representatives to the conflict area long ago — and without asking Belarus for permission. They should be operating on both sides of the border, as their presence would certainly make it more difficult to break the law.

An incomprehensible absence

Neither the leader of Poland's ruling party Jaroslaw Kaczyński nor even Lukashenko would dare to keep the UN, UNICEF, OSCE or the Red Cross out of their countries.

In recent weeks, the services of one UN state (Belarus) have been regularly violating the border of another UN state (Poland). In the nearby forests, children are being pushed around and people are dying. Despite all of this, none of the international organizations seems to be trying to reach the border nor taking any kind of action required by their responsibilities.

Their absence in such a critical time and place is completely incomprehensible, and their lack of action raises questions about the use of international treaties and organizations created to protect them.

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