— I'd like to start our discussion about birds with folk sayings. Before talking to you, I stepped onto the balcony and gazed at the Moscow sky. Today, it's clear. A few birds I spotted were soaring high above. Is it true that if birds fly high, the weather will be good, and if they fly low, there will be rain? Is there a scientific basis for such superstitions?
— Yes, there is. These superstitions are typically rooted in human observations, which often hold some truth. While studying at the Faculty of Biology of Moscow State University, I helped organize a biology contest for school students, and we loved to pose questions with no single answer. Students would propose various solutions, and the one who suggested the clever ones won and advanced to the next round. In the case of swallows flying low before rain, there are several plausible biological explanations. For instance, a change in pressure could cause the insects that swallows feed on to fly lower, and in turn, the swallows hunting them would also fly lower. I could propose several other hypotheses, but it's essential to understand that they would be specific and not applicable to all bird species. For example, in Africa, a change in pressure might not lead to a change in weather conditions and insect behavior, and not all our birds are insectivorous.

— So, can we trust the swallows?
— If they live near a village in the central part of Russia, then yes.

— In late August, flocks of birds were twirling in the Moscow sky. But now, after half an hour of observing from the 24th-floor balcony, I've only seen a handful of birds. Is this related to bird migration, which you are studying? What routes do our Central Russian birds prefer? What prompts them to migrate?
— Yes, it is, in fact, due to migration. All migratory birds depart roughly at the same time, and by October, the skies are empty. Numerous factors trigger migration. The most apparent ones are the lack or inaccessibility of food during winter and low temperatures that not all birds can withstand.
There are also other, less obvious reasons for migration. One such reason is the length of daylight hours. In winter, days become shorter, and birds, except owls and a few other species, feed during daylight hours. So, they have plenty of time to find food in the summer but very little time in the winter.
This difference in daylight hours is most pronounced in the Arctic, where it's bright 24/7 in the summer and dark 24/7 in the winter. That makes it clear why Arctic birds fly south for the winter. They can't search for food in complete darkness. It also explains why they return to the Arctic in spring. At first glance, it seems that once the birds have flown south, they should stay there. But they return to the Arctic, where conditions are far from ideal:  it's cold, food is scarce, and the breeding season is short. But there is a reason why birds make this journey.
I hypothesized that they return because in the Arctic during summer, it's daylight 24/7, which allows them to forage for themselves and their offspring all day and night. Therefore, it's a highly advantageous environment. But then one could argue, “What about sleep?” After all, they still need to sleep at night, whether it's dark or light. But it turns out that birds don't necessarily need to do that.
Here is how it was discovered. There was a study in the Arctic during summer when it's light 24/7. Scientists caught pectoral sandpipers, attached special loggers to them to measure brain activity, and tracked their sleep patterns. It turns out they are awake 95% of the time and can go without sleep for three weeks. Then, there was another study on  great frigatebirds during migration. Their non-stop flight across the ocean takes ten days, and it turns out they only sleep about 45 minutes a day during that time. During these minutes, they ascend and begin to glide slowly. The rest of the time, they're awake.

— Does that mean sleep isn't essential for birds?
— These studies have challenged the idea that sleep is absolutely necessary and that birds need to regularly become completely inactive, like mammals and, consequently, humans. Birds seem to sleep at night simply because they have nothing else to do. And since there is nothing to do, they can conserve energy and sleep, but it's not a requirement.
When I learned about these studies, they certainly struck me. At the time, I was studying other things like food chains and bird feeding behavior, focusing more on predatory birds nesting in the Arctic. To understand what they feed their chicks, I set up camera traps in their nests. Looking through the photos, I found that the bird regularly sleeps in the nest only when the chicks are small and it is shielding them from bad weather. But when the chicks grow up and no longer need protection from the rain, the mother bird no longer spends the night in the nest. I had two possible explanations. Either the bird doesn't sleep or sleeps somewhere outside the nest, which is strange because it would leave the chicks unprotected. I started investigating whether a bird could stay awake for such a long time. I found out that it could, and then I thought that maybe that's why they fly to the Arctic to breed.
Then I started thinking that even though a bird may be awake 24 hours a day, it doesn't necessarily mean it can gather more food than if it had 16 hours a day. I know from personal experience that you can come to work for eight hours without getting much done. Sometimes, all you do is scroll through your Facebook feed, drink coffee, chat with colleagues, and pick your nose, so to say. On the contrary, you can work for two hours and accomplish much more than on some full workdays. I'm sure many people can relate to this. Birds have 24 potential hours in a day, but perhaps they have an energy cap, a certain calorie expenditure limit that they physically cannot exceed. So, I started thinking about how to measure this energy in birds.

— Did you keep a food diary and record all their physical activity? I understand how health enthusiasts do it, but “counting profit and loss” in birds is another story...
— Indeed, it's more complicated in birds, but there are lab ways to do that. You place the bird in a cage, feed it a specific amount of food, and then determine the number of calories it consumed. Next, you collect its feces, incinerate them in a calorimeter, and calculate how much energy is expended and what remains. But obviously, this can't be done in the wilderness, so I began exploring alternative methods.

— Is it possible to attach a bird-friendly fitness tracker to a bird?
— Yes, that's precisely what I'll be talking about. Pedometers, fitness trackers, and calorie calculators all use an accelerometer, and indeed, you can attach one to a bird. An accelerometer is a sensor that determines an object's position in space. Nowadays, it's found in every mobile phone, serving to rotate the screen when you turn the phone and also to count steps and calories when you exercise. In cars, the accelerometer helps distinguish between sudden braking and an emergency, triggering the airbags in a flash.
These sensors on birds measure their position in space across three axes, and it turns out they are a veritable Holy Grail for studying bird behavior and energy consumption. First and foremost, they allow us to understand what the bird is doing at any specific moment — whether it's standing, running, flying, perched on a branch, or incubating eggs in a nest. If it's flying, is it hovering or flapping its wings? And how frequently does it flap its wings? Most importantly, just as the accelerometer in your phone calculates how much energy you've burned during your morning jog to the store, the same accelerometer in the logger on a bird calculates how much energy it has expended during its morning search for food.
Secondly, all of this can be monitored remotely. You catch a bird, equip it with a logger that transmits all this information via cellular communication to a database, and then you can sit at work, sip your coffee, and receive the data. Of course, scientists also studied bird energetics in the wild in the past. They would sit in hides, observing. But they could only observe part of the behavior. After all, a bird doesn't always stay in one place. And if you chase it all day, you might end up with a bird that has spent the entire day simply trying to escape from you. And, of course, many would love to follow a bird to warmer climates for the winter, but for obvious reasons, this is extremely challenging. Now, however, you can gather data on what the bird has been doing throughout the day, every day of the week, all year round.
I began attaching these "fitness tracker" transmitters to birds and observed how much energy they expended. It turns out the birds that migrate to the Arctic not only have more time and opportunities to gather food but also expend more energy in the Arctic and can, therefore, feed more offspring. So, it really is a brilliant idea to fly to the Arctic for the breeding season despite the cold and summer snowfalls.

— Does that mean migratory birds have a higher energy limit than non-migratory birds, and they can't realize their physiological potential in short daylight hours?
— It seems that way. But there is another factor to consider. Perhaps a hypothetical bird living in the tropics or mid-latitudes could gather the food it needs to feed, say, three chicks, but it would have to work very intensively to do so. In the Arctic, there is more time to gather the same amount of food, allowing for a more relaxed, snail's pace.
This opens a new chapter in research on the so-called pace-of-life syndrome hypothesis. In short, it's an extension of the r/K selection theory, which is popular in ecology. According to this theory, there is a gradient between species, populations, or even individuals who live fast and vibrantly and die young and those who live slowly and leisurely. Studies of bird energetics and migration in the Arctic show that staying put and living in the middle latitudes is possible, following the principle "bloom where you're planted". In that case, you'd have to live very intensely and might even die early. Or you could migrate to a place where it's always light with no dark periods and live a slow and leisurely life. As they say, to each their own.

— So, if birds want to lead a measured life or if the duration of daylight doesn't allow them to fulfill their full potential, will the time of migration coincide with the equinoxes?
— Yes, that's what I talked about earlier — birds migrate around the same time. They all depart around the end of September, on the day of the autumn equinox. So, if you're in the Arctic, your days are longer than in the mid-latitudes until September 22–23, after which they become shorter. And if you want to experience all the longest days, you need to be in the Arctic until September 22–23 and then fly south. Similarly, in spring, you need to fly north on March 20.
But this is ground level, a foundation. Many other factors and limitations come into play. For example, there is still snow in the Arctic in March, and there isn't much for herbivorous or insectivorous birds to do there. Yes, the day is longer, but you can't gather more food because that food isn't available yet. Therefore, many birds return not on March 20 but much later, in late April or even May. It turns out that there are many factors influencing migration timing, but the length of the day remains a fundamental factor.

— There is also a theory that birds return north because the tropics are full of their birds, and Arctic birds have to compete with them, not always winning the competition. Does that mean this and other theories are now taking a back seat?
— The theory I told you about is receding to form an underlying layer. It's like a background layer in a Photoshop image. What you're saying also holds true but as another constraint or layer. Most theories explaining the timing and reasons for migration are not mutually exclusive. Rather, they complement each other.
Competition in the south is certainly higher than in the Arctic. As you move north, predation pressure decreases, although this is a contentious issue. In years when there are many lemmings, predators hunt them, and birds like geese and waders thrive. And when there are no lemmings, predators switch to hunting birds. There is also a hypothesis about parasites, suggesting there are far fewer parasites in the north. All these numerous factors affect different species in different ways. Their influence can vary from year to year, and their significance varies from region to region. This is the life we're studying. And the answers to simple questions usually turn out to be complex and multifaceted, as is true in our case. However, the length of daylight hours is the baseline, the ground level that remains constant no matter what. Even if a region's climate warms up, the permafrost melts, and ecosystems change, the duration of daylight hours will stay the same. It's always been dark in the Arctic during winter and will continue to be so. And birds will continue to migrate from there, even if it becomes warm and comfortable in winter because almost none of them know how to search for food in the dark. Except if...

— Except if the Earth's orbit undergoes a fundamental change or the tilt of the Earth's axis shifts. That's clear. We've discussed birds in general, but are there any particularly interesting ones? I was, for instance, amazed by the studies on the Arctic tern, which migrates from the Arctic to the Antarctic or vice versa every six months.
— Indeed, the Arctic tern is an excellent example that validates our hypothesis as it travels from one pole to another. This raises the question of why it behaves this way. The distances are enormous. It's several tens of thousands of kilometers. Why does it need to do this? Why not just settle near the equator and spend the winter there?
A compelling explanation is the duration of daylight. When it's winter for us, the tern in Antarctica is experiencing summer, with daylight around the clock. The only time it's dark for it is during the brief periods when it’s in flight. Twice a year, it has to endure short periods when, for some reason, "the lights go out," but for the rest of its life, this anomaly doesn't exist. The rest of the time, it lives in constant daylight, where everything is visible and it can fly, search for food, or rest. There is no situation where “the lights go out,” and it has to wait for them to come back on, unsure if a predator is approaching. This behavior makes perfect sense from the tern's perspective.

— What about the tern's sleep patterns? Does she get at least 45 minutes of sleep every two weeks?
— As far as I know, no one has studied this yet. Such research is quite complex. Learning how to attach transmitters to birds is one thing, but implanting electrodes in their brains is another matter entirely. That requires surgical expertise. But I believe such research is on the horizon.  The tern is a fascinating research subject.

— Your bird migration research is published in top scientific journals. Even your fellow biologists probably imagine an ornithologist as a field worker in camouflage with binoculars around their neck, but you've told me that today's ornithologist sits in an office, sipping coffee while receiving real-time data from birds wearing something akin to Apple Watches. So, what does cutting-edge ornithology look like? I mean the kind that gets published in Science and Nature.
— The somewhat belittling towards field biology among many molecular biologists is mainly due to the accessibility of these fields to the general public. Anyone can buy a pair of binoculars on Avito for the price of an electric kettle and go birdwatching in the park. But to conduct PCR tests, you need quite expensive equipment and a lab. Although, I'm confident that in 40–50 years, you'll be able to buy not just binoculars but also a DNA sequencer on Avito for the price of an electric kettle. Many housewives will buy their equipment, conduct genome-wide association studies of their cats in their kitchens, and post Manhattan plots on Instagram. Meanwhile, Martian scientists will be writing proposals for Mars exploration and will be surprised that geneticists and other strange people in white coats, who spend all their time in labs and never go out, are also getting published in Nature and Science. "What have they discovered in their labs that my grandmother hasn't already posted on Facebook?"
But seriously, yes, that's how most people perceive ornithologists. This image is even more prevalent in Western countries than in Russia. That's because there are many people there who birdwatch as a hobby, the so-called birdwatchers. In Russia, it wasn't common to have birdwatching as a hobby. Now, thanks to many people's efforts, birdwatching is becoming more popular here as well.

— Yes, Nina Sadykova, who used to work at the Institute of Plant and Animal Ecology of the Ural Branch of the Russian Academy of Sciences, organizes birdwatching tours around Yekaterinburg. She shows the participants around and educates them about the local environment...
—Yes. There is a lot of this happening now. In Moscow, for example, an organization called Ptitsy I Lyudi [Birds and People – editor’s note] does this. There is Birdwatching Moscow, which offers training through the Norwegian BirdID program. Andб of course, the development of phones and apps helps. Someapps make bird identification easy. Competitions are held to see who can spot the most diverse range of birds in different locations, adding a competitive element to birdwatching. A lot of this is happening in Russia now, but it doesn't compare to the scale of it in the West.

— As far as I know, ornithologists often enlist birdwatchers to monitor populations, say, nightingales in the floodplain of the Moscow River, but this isn't exactly avant-garde ornithology...
— Yes, that's correct. This is what we call citizen ornithology. A lot of people are involved in Moscow. There is a large project called Ptitsy Moskvy [Birds of Moscow – editor’s note], led by Mikhail Kalyakin, director of the Zoological Museum of Moscow University. Anyone can participate in various studies conducted under this project. They have some intriguing and relevant initiatives.
If by avant-garde ornithology we mean studies published in Nature and Science, then it must involve a significant shift in the established scientific dogma. It could be studies that only use binoculars and wading boots as methods, but more often than not, they involve some new methods. Like in any field of science, the methods of ornithology are rapidly evolving. When a fundamentally new method emerges, it provides an opportunity to learn something new and expand our knowledge, often allowing us to construct new concepts and challenge established dogmas.
What we're doing now — studying migration using transmitters, or bio-logging — is currently experiencing its golden age. Although these methods and technologies were developed quite a while ago, there has been a surge in research in this area because of the miniaturization of these devices and the advent of GPS, cellular communication, IoT technologies, et.c. Miniaturization allows these technologies to be used to study the behavior of  many species.
We've also been engaging in methodological innovation. Before the special military operation started, we had a joint project with Roscosmos called ICARUS. It's not entirely closed and is still running, but separately in Germany and Russia. The project aimed to create a fundamentally new technology for tracking birds.

— Something more advanced than GPS, you mean? It seems to be quite accurate in pinpointing the location...
— Exactly. The bird's position is currently determined by GPS, and scientists receive the information via cellular or satellite networks. But not every place on Earth has cellular coverage. Satellite coverage is global, of course, but satellite transmitters are heavy. They weigh 15–50 grams. Most of their weight is the battery, which allows them to send a powerful signal to satellites in high orbit. You can still attach these devices to a large bird, but many bird species weigh less than 120 grams. These devices are not suitable for them, making studying these species difficult.
Creating a satellite constellation in low orbit, to which it would be possible to send a signal with a small battery, is very expensive. Although now, with the dramatic reduction in launch costs and the development of CubeSat technology, this has become much easier, and it seems that this is the future of animal tracking.
But when our project started, launches were expensive, and CubeSat was still in its relative infancy, so the German Aerospace Center (DLR) launched the ICARUS project with Roscosmos to create a new technology for tracking animals from space. The scientific organizations involved were our institute, then known as the Max Planck Institute for Ornithology [now Max Planck Institute of Animal Behavior], and the Institute of Geography of the Russian Academy of Sciences. The goal was to create compact transmitters for birds, the signals from which would be received on the International Space Station (ISS), located at a relatively low altitude of about 400 kilometers. The low altitude would enable the reception of a less powerful signal, thus allowing for the use of a relatively lightweight battery and, consequently, the production of a light transmitter.
The process was lengthy and complex, with constant disputes over nuances and time-consuming detail negotiations. Despite the pandemic, all receiving equipment was successfully delivered to the ISS in 2020, and astronauts installed an antenna on its exterior in open space. Once everything was ready, we began debugging the equipment and tagging the first animals. In Russia, twenty major projects utilized this technology.
Indeed, there were numerous challenges. The initial transmitter models didn't consistently perform well across all species. For instance, certain bird species would bite off the antennas transmitting signals to the ISS. However, despite these challenges, we had successfully fine-tuned everything, by the end of 2021, and developed a robust transmitter with sturdy antennas.
But with the commencement of the special military operation, Roscosmos declared that all collaborative projects with foreign entities were terminated. Currently, the Russian component is operational. The antenna is mounted on the ISS, and Russian scientistsreceive the data from the transmitters through the Institute of Geography of the Russian Academy of Sciences. However, there are no new transmitters available. This is because the German team was in charge of equipment development. The antenna remains affixed to the Russian segment of the ISS, as no one has removed it. The transmitters, however, were produced in Germany, and now the Russian team cannot acquire new ones.

— That's unfortunate.
— The current situation is such that while the technology exists and is functional, Russian ornithologists lack transmitters. On the other hand, the Germans have transmitters but lack space equipment. So, it seems that Russian engineers will attempt to manufacture theirtransmitters, while the Germans will strive to launch their equipment into space — most likely not on the ISS but on satellites. We'll have to wait and see how this unfolds.
Meanwhile, the number of companies specializing in satellite and GSM transmissions is increasing. These companies are beginning to compete, leading to improvements in transmitter quality, reductions in size, and the introduction of more features, such as built-in accelerometers in many transmitters. We're receiving an increasing amount of information, and the cost of obtaining this information is decreasing.

— Abundant information can often lead to fundamentally new knowledge as it gives rise to various meta-studies, and big data analysis can reveal something entirely new..
— Absolutely. For instance, there is a common belief that birds migrate from north to south. However, in reality, there are countless migration routes. Among our migratory birds, some fly to Africa, while others go to Southern Europe. Some travel only 200 kilometers, while others cover thousands of kilometers. Some migrate from the Arctic to mid-latitudes, while others move from mid-latitudes to southern latitudes. And all this variety can exist within a single species. This raises a multitude of questions related to the ecology of these species, and these questions can be explored.
We now have access to a vast amount of previously unavailable, unseen, and unknown information. This changes our understanding of fundamental concepts that are worthy of being written about in articles, including those published in top-tier journals.

— Could you please provide an example of a study that has challenged, expanded, or shifted a dogma?
— When studying the migration of peregrine falcons across their entire Russian range, from the Kola Peninsula to Chukotka, ornithologists discovered that some migrate short distances while others migrate long distances. Using genetic methods, they found that there might be specific genes responsible for long-term memory, and if these genes are present, birds can migrate over long distances. There are also those who lack this gene, and they migrate shorter distances. This suggests that the extent of migrations and wintering locations could be genetically determined. These studies were published in Nature. Also, earlier, we discussed research on bird sleep. These studies were published in Science in 2012. There, scientists used new methods and technologies, implanting electrodes in the brains of animals, and they realized that not all animals require sleep as we understand it. This, too, represents a paradigm shift.
However, it's worth noting that not all influential articles on ornithology have been published in top-tier journals. There are many foundational studies with a high number of citations published in reputable journals with a lower impact factor. This might sound cliché, but I believe scientists should primarily pursue what interests them, not what is likely to be published in top journals. And at some point, they might discover something that challenges our understanding of how the world works. And, of course, it's important to remember that if you don't submit your article to Nature or Science, it definitely won't be published there.