Hi and welcome to Corvid Cleaning, an enterprise that is investigating the possibility to work together with crows to clean up litter. We get help cleaning up the trash, they get some yummy food. During the last week of January 2022 this idea got picked up in the media and got reported in a lot of outlets. This was a bit unexpected; the idea was to avoid media until the project got further. The coverage has generated a lot of questions and friendly comments, so I’ve quickly put together this simple website to answer the most common ones in a FAQ.

Best wishes, and throw your trash in the bin
Christian Günther-Hanssen

See the birds at work

Hooded crows picking training sticks and getting peanuts as a reward.

Can be used by media outlets with attribution to Christian Günther-Hanssen.


Q: I’m from the media, can I do an interview with you?
A: Sorry, there’s no time to talk to all of your right now. So no more interviews, but you can use this information and the clip above, with attribution to Christian Günther-Hanssen. Try again in August though.

Also check out these press photos from the Södertälje Science Week seminar on 4th February:

Q: So how does this work?
A: The idea is to train the birds to pick litter and throw it in a special vending machine, or bird bin. When they do that they are rewarded with food. The bin will tell litter apart from other items such as stones and leaves and only reward litter. The birds take part as much or as little as they wish, and the only human involvement is to empty the bin and refill the food. Even during the training the birds only interact with the bin.

Q: What has been done so far?
A: The hardest part of the project is done, which is to find the teaching method for the birds to proove they can indeed learn the exchange principle. This was tricky especially since the birds are wild and won’t take part if they’re bored or find better food elsewhere. During the past year a functional teaching method was however found, together with participating birds at Hagby Recycling Center in Täby, Sweden.

Q: How does the training work?
A: Step by step. The bin will have a training mode where it gives food differently. The birds are rewarded for each step they get closer to the final behaviour. The first step for example is just to get them to even take free food from the bird bin, since they don’t know that it’s harmless and avoid it. The final step is to get them to transfer between items placed onto the bin and start picking from the ground.

Q: What birds are taking part?
A: The focus is corvids (crow like birds) in urban enviorments. So far it has been Hooded Crows, but Magpies and Jackdaws are also expected to soon be part of the project. In other parts of the world other corvids would be equally possible. The reason these birds are used is first and foremost that they are among the most intelligent of all animals, and have no issue understanding the trade of litter for food. The second reason is that they already live in human enviorments, so they don’t have to move and you don’t interup their ‘natural’ behaviour since their lifes are already shaped by humans. Birds living in a natural enviorment are not part of the project.

Q: What litter will they pick?
A: The first focus of the project is cigarette butts, since they make up more than 60% of all litter items and are simple for the bird bin to identify as trash. The ambition is of course that all harmful litter should be cleaned when possible, as long as it does not pose a threat to the birds.

Q: What is left to do?
A: While the project already demonstrated that the birds can learn the principle, some question marks remain. How far will the bird go to bring something, how often will they pick, what other effects does this have on bird health and behaviour? Corvid Cleaning is now preparing a pilot project where, for the first time, this would be tested with birds picking real litter thrown by the public (rather than items someone put out for them). During this pilot the remaining questions will hopefully be answered. This pilot is likely to take place in Södertälje, although talks are still ongoing and more financing is required.

Q: Is this really new? I’ve seen stories about this before.
A: There are in total 4 independent projects, Corvid Cleaning included, that have managed to train wild birds to pick items in return for food. There are additional projects who have had this idea, some who got significant media coverage, but who never showed they could train the birds. There is no one who have tried to let wild birds pick real litter thrown by the public, so the pilot currently being prepared might be the first to accomplish that.

Timeline of Corvid Cleaning and other similar projects.

Q: Can I do this at home?
A: Depends on how good you are at building things. The easiest way to get a machine is to buy The CrowBox, which is a product you can buy (from someone else) and build yourself. Note however that no bird has completed the last step in the training using the CrowBox. The Corvid Cleaning design is not available to the public, and is ongoing redesign anyway.

Q: How does this effect bird health?
A: No one knows, but we intend to find out. What we do know so far is that cigarette butts contain a lot of nicotine and other compound that are dangerous if inhaled or ingested. Since the birds will do neither it’s unknown if they will get anything in them at all. It is also known that birds in urban environments often eat human junk food and get nutrition deficit as a result. Chances are pretty good that it’s possible to put the birds on a better diet and improve their overall health with this solution.

An important part of the upcoming pilot test is to monitor the levels of compounds in the birds, in order to remove the unknowns. Should any reach dangerous levels the project will be modified to exclude any items containing those compounds.

Q: How this effect bird behaviour?
A: This is another question that the pilot will give insight into. It will change their food searching behaviour obviously, but that might be it. These are wild birds taking part voluntarily, and birds that already are used to living in an environment shaped by humans. Their current behaviour is not “natural” as such, so it’s not necessarily a big change for them to just interact with the human world in a slightly different way.

Q: How do I keep up with any development?
A: We don’t have a newsletter yet, but if you just send an email to news@corvidcleaning.com you’ll be on the list once there is one.

Q: Is it possible to join the Corvid Cleaning team?
A: The idea was to finish the pilot, go public, then build a bigger team. Now this is already public, so send an email to crowquestions@corvidcleaning.com and we’ll talk I guess. Mechanical engineering, AI image recognition, bird health and behaviour are some of the the main areas involved in this project.

Q: My question is not listed, how do I get in touch?
A: Send an email to crowquestions@corvidcleaning.com