Czech scientist: animal migration threatened by climate changes


A large number of wild animals, especially birds, travel across the Czech Republic each year to breeding grounds in the north in search of more food and smaller predation risks. However, a new study co-authored by Czech scientist Vojtěch Kubelka shows that many of these animals no longer profit from migrating to the northern latitudes due to environmental changes associated with climate change.

What kind of impact do these changes have on migrating animals? And are they threatened with extinction? These are just some of the questions I discussed with Mr Kubelka, and I first asked him what exactly forces the animals to travel such long distances every year:

“There are many migrating species all over the world, usually from the tropics, migrating towards the north temperate and Arctic regions and there have been various theories why they do so. There are three main advantages for them.

“One is that they encounter here in the north and further in the north, in the Arctic, a seasonally high peak in food supply, which is not available in the same amounts for example in the equatorial regions. So this is one big advantage.

“There are also fewer parasites when you go further up north and a lower predation rate. So those are three main advantages which lots of migration species benefit from when travelling to the north for reproduction.”

Is the Czech Republic a target country for some of these species?

“It’s obvious that many populations are struggling to keep up with those changes and inevitably many of them will lose.”

“We are, actually. We are in the middle, which means that some species from the tropics or the Mediterranean region come here to breed, and on the other hand we have several species that come here just for the winter and then they travel to the Arctic to breed there.

“And of course we are a stopover for many birds and some kinds of insects that winter in the south, pass through our country and then continue towards the north.”

Your recent study has shown that some of these species no longer profit from migrating to the breeding grounds in the north temperate and Artic regions due to environmental changes associated with climate change. What kind of changes are we talking about?

“In this case, we really covered those three expected advantages and investigated them in more detail. We have some 25 studies describing the disruption to the former benefits for migratory birds, including food supply, parasites and predation.

“Unfortunately for migrating animals it is indeed true that for many populations and species the migration is not as beneficial as it used to be.

“The disruptions to food supply may account for example for tropical mismatch, which means that the migratory animal arrives later or is not well synchronised with the peak of the abundance in the north.

Vojtěch Kubelka | Photo: Jan Bendl,  Charles University

“Due to the warming climate, the phenology of the leaves or insect emergence can be quicker in the Arctic, and the birds that migrate from tropical regions arrive late for those changes. Their chicks can have a lower survival rate, they can starve or not be feed enough to travel back South.

“This is the disruption to the food supply. Similarly, following warmer temperatures, many parasite and pathogens enter the north temperate and Arctic regions and we have also encountered increasing predation pressures in these areas.”

So what impact do these changes have on some of the migratory species? You have already mentioned starvation…

“Definitely, if the chicks are more likely to die, then population numbers will fall and it could inevitably lead to extinction. Of course we want to prevent this, but this is the population dynamics.

“Small changes, such as increased predation on nests, leads to less chicks joining the population and less migrating animals.

“Unfortunately, many migrating species already have declining populations and the disruptions to the earlier advantages can definitely contribute to this trend.”

How exactly do the species react to these changes? Can they develop some survival strategies?

“They are definitely trying. It’s obvious that some species can speed up their arrival to the Arctic and synchronize with the changing climate, but those are usually species that winter nearby. That means they can foresee the changes and arrive there in time.

“Unfortunately, this doesn’t apply to the species from the equatorial region, because they don’t know that the Arctic is already warm. They have been used for millions years travelling according to some schedule that worked really well, but right now it doesn’t.

“So the species are trying. They can for example avoid places with higher predation but if we have lots of places where these changes are happening than it is more difficult for them.

“What is also really important as well is to cooperate across whole nations, because migratory animals have no boundaries.”

“Unfortunately the current changes are really quick. There is not much time for ecological adaptation. It’s obvious that many populations are struggling to keep up with those changes and inevitably many of them will lose.”

Can this ultimately affect the whole ecosystem?

“That’s absolutely right, because we are not losing only the migrating animals, we are also losing the interactions, which is really important for the functioning of the whole ecosystems.

“We know that in the Arctic, the food supply has been altered both for migratory and local predators, such as lemmings and voles, small rodents that create the baseline for the Arctic food-web, which have disappeared in many places.

“This results in higher predatory rates for migratory birds, it affects the predators which don’t have enough food supply and inevitably they also perish, so it is cascading through the whole ecosystem.

“So it’s obvious that we humans are affecting all the interactions in the ecosystem which can have unknown and quite serious consequences for the whole ecosystem.”

Photo: Vojtěch Kubelka

What species has your research focused on and where there any species that we encounter here in the Czech Republic?

“Definitely, the species that we encounter are passerines, or singing, birds, like flycatchers. We also have a lot of shore birds here in the Czech Republic, birds that usually migrate through our regions, breeding far in the north or even here and wintering in the south.

“We don’t have large migrating mammals in the Czech Republic, such as elks, but we have some bats, that migrate across Central Europe.

“There are several dragon flies, migrating to our regions too, one butterfly species regions from the Mediterranean, called Painted Lady, but again, with warming climate, this may change in the future.”

Your current study is a comparative perspective of already published research. Did you work directly in the field in some cases and what exactly did this research look like?

“We did work on various case studies involved in this overview. We have worked with nest predation of shore birds, where we used already published data.

“But for several other data sets we really worked directly in the field, for example in the Caspian Lake area, or in Chukotka in Russia, but also in South Bohemia with the northern lapwings, who unfortunately have increasing predation rates.

“In the field we work mostly with shore birds, which means we arrive at the breeding ground and carefully observe their behaviour, we try to locate the nest and with minimal disturbance we observe the nest and follow the outcome.”

Painted Lady | Photo: JirkaSv,  Wikimedia Commons,  public domain

Finally, what exactly can be done to mitigate the changes?

“Our article is important from the perspective that we really set up approaches to how we can really help migrating species. We can start from direct nest protection against predators and local management to improve habitats and from there move to large scale conservation from there.

“Migratory species are really fragile and susceptible to changes in that they are dependent on staging areas, on wintering areas and on breeding areas and whatever you take out of the chain can really impact the whole population.

“We really need to target our conservation perspectives across the whole life cycle of those birds.

“What is also really important as well is to cooperate across whole nations, because migratory animals have no boundaries. So if we want to save them, we have to cooperate and I am sure these animals are worth it.”