Annonse
10 things you didn't know about house sparrows
In the past, people made soup from house sparrows.
Published
Here are ten facts showing there’s more to the house sparrow than you might think.
1. Has lived alongside humans for thousands of years
Most wild animals avoid humans. That's not the case with house sparrows.
"It's natural for house sparrows to live alongside humans. They've done so for almost as long as we have practiced agriculture," says Henrik Jensen, who researches house sparrows.
He is a professor at NTNU.
Annonse
More than 10,000 years ago, people in the Middle East began farming the land. That provided food for humans and house sparrows. Since then, they have adapted to living alongside us.
"A large part of the house sparrow's diet comes from leftover food connected to what we grow and produce, especially grain-based products," says Glenn-Peter Sætre.
He is a professor at the University of Oslo's Department of Biosciences and has written a book about the house sparrow.
They eat seeds in our gardens and grain in fields and in barns. The small birds also happily pick up crumbs that fall from café tables.
"You’re unlikely to see a house sparrow in forests or remote wilderness. It prefers to live near us," says Sætre.
2. The house sparrow can be found all over the world
Most animals and birds adapt to one particular climate or environment. The house sparrow is an exception.
"The house sparrow is the wild bird species with the widest geographical distribution in the world. It's found on every continent except Antarctica," says Sætre.
House sparrows were brought to certain countries and continents by humans.
175 years ago, there were no house sparrows in North America.
Back then, people in New York were struggling with caterpillars that were eating the leaves on trees in city parks. To solve the problem, some brought house sparrows over from England.
But they had misunderstood the bird's diet: Only the chicks eat insects, and only during the first two weeks after they hatch.
By then, it didn't matter. House sparrows thrived and spread quickly.
This started the war on sparrows. Some wanted the birds eliminated, arguing they were aggressive, dirty, harmful to the ecosystem, and that they pushed out local birds.
Annonse
Others wanted to protect them. They pointed out that they had been brought there by humans, and that they deserved to live undisturbed.
The sparrows won. Today, they are found all across the United States.
3. The house sparrow lives in all kinds of places
House sparrows usually build their nests close to people, often under the roofs of houses and barns. They also nest in trees and bushes.
The small birds are highly adaptable. Simple nests made of dry grass and feathers have also been found on traffic lights and road signs.
Nests and house sparrows have even been found in mines, many hundreds of metres underground. They have been observed on the 80th floor of the Empire State Building in New York.
House sparrows fly in and out of factories and shopping centres. Some move in permanently.
"In some places, local house sparrows have learned to open electronic doors to shopping centres by fluttering in front of the sensor," says Sætre.
4. Norway has a completely unique research project on house sparrows
Studying wild animals and birds is difficult. How can researchers be sure that the animals they catch and examine are representative of the entire species?
When it comes to house sparrows, the researchers at NTNU have gexcellent control. They have studied all the house sparrows on 18 islands off the coast of Nordland.
"We've been working on this for more than 30 years. Because the house sparrow doesn’t migrate, we’ve been able to follow more than 38,000 birds from the moment they hatch until they die," says Henrik Jensen.
The goal is to learn about the birds' genetics and ecology: What happens when habitats become fragmented and shrink, and how birds are affected by changes in climate and environment. This provides knowledge about how inherited traits affect a species' ability to adapt to environmental change.
Every summer, Henrik Jensen travels out to the islands. His daughter Våga has joined him since she was six years old.
"It's great to be part of something this exciting," says Våga, who is now 13.
She has learned how to catch sparrows, take blood samples, and put rings on their legs.
"We learn who's still alive, who's died, and which birds have flown to a different island," says Jensen.
The research has also revealed just how dependent house sparrows are on humans.
"On some of the islands, farms closed down and people moved away. When that happened, the house sparrows disappeared too," says Jensen.
5. House sparrows are notoriously unfaithful
House sparrows live in pairs and share the work of raising their chicks.
But the females are unfaithful. Studies have shown that around ten per cent of the chicks have a different father.
Researchers still aren't sure why females choose more than one father for their young. It may increase the chance that more eggs are fertilised. Or perhaps because they want males with good genes that make the chicks strong.
Males keep a close watch on their partners to prevent infidelity. And when they suspect that the chicks are not theirs, they provide less care and food.
6. They love to bathe
House sparrows enjoy bathing – in sand.
"They lie on their bellies in the sand and flap their wings around. That way, sand and dust particles cling to the oils that coat their feathers," says Glenn-Petter Sætre.
After bathing, they preen themselves. They use their beaks to remove dust, dirt, and small parasites such as feather lice.
"The dust basically helps keep the plumage clean, nice, and free of parasites," he says.
7. The house sparrow is smart
To survive on human food, a bird has to understand human habits.
"In some countries where people use milk bottles with lids made of metal foil, sparrows have learned to peck holes in the foil to get to the milk," says Sætre.
They have also learned the colour codes.
"Different types of milk have different-coloured lids, and the sparrows prefer cream and whole milk over skimmed and low-fat milk," he says.
8. Norwegians used to eat sparrows
Small birds were once caught and eaten in Norway, most recently during World War II when food was scarce.
Most viewed
It was usually thrushes, but sparrows also ended up in the pot.
In Christopher Hammer's Norsk Kogebog (Norwegian Cookbook) from 1793, there are recipes for stuffed sparrows and sparrow soup.
The birds were plucked and stuffed with forcemeat made from other birds, then tied up and roasted, ideally on a rack or spit.
Afterwards, stock was made from the carcasses, and it was seasoned to taste. Hammer recommended adding both something sweet and sour, and finishing the dish with appleas as garnish.
9. Most die
"The oldest house sparrow we followed lived to be 11 years old," says Jensen.
But that's far from normal.
House sparrows have chicks two or three times a year. Five eggs usually hatch each time.
Out of those five sparrow chicks, it's usually only one that survives the first winter.
"The chicks are taken by sparrowhawks or cats. And it's also tough for them in autumn and winter when it gets cold and there's less food," says Jensen.
Chicks do better when people provide food, and when the birds can stay in barns where there is both food and warmth.
Jensen's research also shows huge differences between individual birds: about half of adult sparrows never raise any offspring to adulthood, while others manage to produce as many as 20 chicks that survive to become adults.
10. The house sparrow is Near Threatened
Since 2000, house sparrow numbers have dropped significantly, according to BirdLife.no. This is happening across Europe, including Norway.
Possible reasons include fewer insects, fewer farms with livestock, and less grain left in fields during winter.
In 2015, estimates suggested there could be up to half a million house sparrows in Norway. Today, the Norwegian Biodiversity Information Center suggests the population may be 30 to 50 per cent lower.
Henrik Jensen has studied house sparrows for 30 years.
"I never get tired of the house sparrow. We discover so many important and interesting things," says Jensen. "And the research on the islands along the Nordland coast is a very good model system for many other threatened species."
———
Translated by Alette Bjordal Gjellesvik
Read the Norwegian version of this article on forskning.no
Related content:
Subscribe to our newsletter
The latest news from Science Norway, sent twice a week and completely free.
