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Citizen science – or the involvement of the public into science research – has become an integral part of research work in many fields. There are thousands of projects anybody can join. In your free time you can record a bird song, classify photos of retina neurons, build a quantum computer in an app game or search for dusty debris disks in NASA’ photos. Another possibility is to make use of a huge amount of data people unconsciously collect – photos and videos of various plants and animals. Such pictures were analyzed by zoologists Peter Mikula, Jiří Hadrava and Tomáš Albrecht from the Faculty of Science of Charles University.

There can be positive, negative or neutral types of relationships between any two species. The best-known example of mutualism – a relationship beneficial for both parties – is plants and their pollinators. Commensalism stands for a relationship beneficial for one species and neutral for the other. Many intestinal bacteria, for examples, prosper from the remains of the food and neither help nor harm their human hosts. These two types of relationships can be found between African birds and large mammals as well. Especially in savannahs, birds are often found sitting on hippos, elephants or antelopes. For birds, the advantage is in saving energy, a better view of the surroundings and increased protection from predators. For large mammals, the bird is not a burden though usually it is not a gain either. Some birds, namely oxpeckers, on the other hand glean parasites like fleas or lice in the fur as well. In such cases, the relationship is mutually beneficial.

Caption: Red-billed oxpecker (Buphagus erythrorhynchus) sitting on the head of an impala (Aepyceros melampus) – the photo was searched via the Google Images platform in the same manner as photos for the analysis were. Source: mirror.co.uk.

Researchers used photos found by the Google Images platform. Pictures from sub-Saharan Africa showing a bird sitting on a mammal weighing more than 10 kg were collected, with domestic animals excluded from the analysis. An immense net of relationships depicting all cases of every association between a bird and a mammal was the result of the work. Oxpeckers – birds specialized in picking parasites from the fur of mammals – preferred impala, buffalo, giraffe and white rhinos as well. Hippos followed by zebra, buffalo and elephants were the favorite companion for all the other birds. Quite surprisingly, the network did not show signs of a “nested” structure. This means that birds do not prefer mammal species which are already visited by a large number of bird species – otherwise a very common phenomenon among the commensal and even more so among the mutualistic relationships.

Results based on photos searched in Google Images may be as reliable as the results of fieldwork, though the former costs less money and consumes less time. In this case, large amounts of data made it possible to create a complex net of relationships between bird and mammal species. Thanks to this, researchers found that birds choose to sit on larger mammal species than previously believed. Even ordinary pictures from holidays or trips can turn out to be a valuable source or information. Do you have some interesting photos like this, as well?

If you would like to know more about citizen science, see some of the links below.


  • Project of yellowhammers’ dialects – a recording of yellowhammer songs: http://www.yellowhammers.net/ (British version)
  • Project of classifications of neuros in retina: http://blog.eyewire.org/en/
  • Project of building a quantum computer: http://decodoku.com/
  • Project of NASA – search for dusty debris disks indicating the formation of new planets: https://www.diskdetective.org/#/
  • Projects of Institute of Botany of the Czech Academy of Science in general: http://www.ibot.cas.cz/en/public-relations/citizen-science/
  • Projects of the Czech Society for Ornithology in general: http://www.birdlife.cz/zapojte-se/pozorujte-ptaky/ (link in Czech language only)

Or just search for “citizen science” and the field you are interested in – there are literally thousands of links out there.

Large-scale assessment of commensalistic mutualistic associations between African birds and herbivorous mammals using internet photos; Peter Mikula, Jiří Hadrava, Tomáš Albrecht, and Piotr Tryjanowski; PeerJ; 2018


Iveta Štolhoferová

Published: Dec 17, 2018 06:50 AM

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