The fidelity of a partner is not a natural thing for a swallow, it is just the opposite. According to long-term research by the Institute of Vertebrate Biology of the Academy of Sciences, young people of the same age in the same nest often have different fathers. This is also confirmed by recent analyzes of swallow DNA that Czech scientists are following in the Třeboň region.
Cow pens are an ideal place for swallows to nest. “This is the eco-farm of the albatross family. Here in their buildings for farm animals, dozens of swallows live for us. There, if you look at nest number 15, there are probably four young ones sitting,” Michael Schulke of the Institute of Vertebrate Biology of the Academy of Sciences told RadioWornal.
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Now he gets to the nest where the baby swallows and puts them one by one into the white cups. “I take one cub in my hand. The first thing I do is weigh it.”
Laboratory tech Lisa is already preparing all the necessary properties for taking blood from cubs that are several days old.
This cub weighs 14.38 grams. We will measure the length of the runners. This is that bird’s leg bone. 10.88 mm,” explains Schulke. He gives the ring to the swallow to show that it was already in his hand and already knows about it.
“You have to hold the babies tightly, but not too tightly. They are fragile creatures,” says the scientist.
Now he takes a needle in his hand and draws blood from the child’s swallow. “We do this for the simple reason of knowing who the fathers of this swallow are, because the males are often unfaithful to the female. So the male feeding the young in the nest may not be the actual father of these young at all.”
Drop of blood
Experienced, he takes the cub between his fingers and the needle, a centimeter compared to a five-centimeter cub, draws blood. “I suck a small drop, a few microliters of blood from the already so-called jugular vein, or jugular vein.”
So it takes good eyes and steady hands. “This was very simple. We now pass the blood from the needle into a small tube filled with alcohol. It preserves the blood sample taken.
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All data measured by Michel Schulke were carefully recorded by his colleague from the Institute of Vertebrate Biology Lisa from Corsica. “We’ll take the samples to the lab, where we’ll get DNA from them. Annually, we take the blood of about one thousand chicks and four hundred adult swallows, and we can identify the fathers of up to 97 percent of the chicks based on the genetic codes. We’re really successful this way.”
When asked if it was likely that each of the four swallows examined had a different father, Šulc replied:
“Here, it is very likely that the young are not 100% related, and that they have a different father, because approximately one in three nests contains a young man born to a different father than the one who actually takes care of him. Of course, it is interesting to study the infidelity of birds, because they can It could tell us some questions about the reproductive biology of these animals, i.e. sexual selection. It could also tell us how many young each individual is able to produce in each season. This is really not possible without genetic analyses.”
Of course, swallows fly far to warm countries. Will the scientists know before they come back again in the spring? “We will certainly be able to analyze our blood samples before the swallows return.”
