Tag Archives: animal culture

The Dying Melody: Habitat fragmentation is killing the songs of our birds

by Piter Kehoma Boll

Birds, especially passerine birds (those of the order Passeriformes) are known for their ability to produce complex and melodic calls, or songs, used for a variety of purposes. Who doesn’t love to hear the birds singing beautifully in the forest?

Passerine birds include two main groups: the Passeri (songbirds), also called Oscines, and the Tyranni (tyrants), also called Suboscines. Both groups are able to produce complex calls, but those of the Oscines are usually more smooth and melodic and sound less mechanic.

However, there is one more difference between the calls of both groups. The calls of the tyrants are genetically transmitted from the parents to the offspring, i.e., they do not need to learn how to sing with adult birds. Among the songbirds, on the other hand, the complexity of the call is largely culturally inherited, i.e., they learn how to sing with other birds of the same species.

400px-orange-billed_sparrow_-_rio_tigre_-_costa_rica_s4e9639_282658498835229

The orange-billed sparrow is a songbird found in the Neotropical region. Photo by Francesco Veronesi.*

A recent study published in the journal Animal Behavior (see reference) analyzed the complexity of the calls of two passerine birds found in the forests of Costa Rica: a songbird, the orange-billed sparrow Arremon aurantiirostris, and a tyrant, the scale-crested pygmy tyrant, Lophotriccus pileatus.

791px-scale-crested_pygmy-tirant

The scale-crested pygmy tyrant is a tyrant found in the Neotropical region. Photo by Chris Jimenez.*

The team compared the complexity of the calls in different populations of each species living in forest fragments of different sizes. The conclusion was that, while fragment size did not affect the complexity of the call in the tyrant bird, it significantly affected the call of the songbird.

Populations of the orange-billed sparrow that live in smaller fragments show a less complex song than those living in larger fragments. As the call in this species is culturally transmitted, this reduction in complexity is most likely a result of cultural erosion. As smaller fragments only support smaller populations, the birds do not interact that much with other individuals of the same species while they are growing up, and as a result their song becomes simpler and simpler.

We, humans, are the ones to blame for that, as you may already know. Our irresponsible practices are not only reducing population size in other species, but are destroying their culture as well.

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

Reference:

Hart, P. J.; Sebastián-González, E.; Tanimoto, A.; Thompson, A.; Speetjens, T.; Hopkins, M.; Atencio-Picado, M. (2018) Birdsong characteristics are related to fragment size in a neotropical forest. Animal Behavior 137: 45–52. https://doi.org/10.1016/j.anbehav.2017.12.020

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution 2.0 Generic License.

Advertisements

Leave a comment

Filed under Behavior, Conservation, Evolution, Ornithology, Zoology

The bat folk songs: cultural evolution in our winged relatives

by Piter Kehoma Boll

For a long time, culture was considered a human trait, but nowadays we recognize the existence of culture in many other species, such as other primates, whales and some birds too. Now there are some evidences of culture being found in bats too.

A group of researchers from China studied the calls of the Chinese rufous horseshoe bat (Rhinolophus sinicus) across different populations and compared them to genetic and environmental variables to determine whether the differences where linked to genetic differences between the populations or to different environments that would force the bats to change their calls in order to use them more successfully.

63992_web

The smile of a cult bat (Rhinolophus sinicus). Photo by Ecohealth Alliance, extracted from Eureka Alert.

The results indicate that none of those two factors were strongly linked to the acoustic differences in the calls. The most likely explanation is that the differences happen due to cultural drift. The bats are teaching a way to speak to their children that is slightly different from what their neighbors speak, even if the neighbors are genetically similar and live in a similar environment.

As an animal’s call is an important variable during mating, this may eventually lead to reproductive isolation even without genetic differences. Culture can also shape evolution!

– – –

Reference:

Xie, L.; Sun, K.; Jiang, T.; Liu, S.; Lu, G.; Jin, L.; Feng, J. (2017) The effects of cultural drift on geographic variation in echolocation calls of the Chinese rufous horseshoe bat (Rhinolophus sinicus)Ethology 123(8): 532-541.

Leave a comment

Filed under Behavior, Evolution, mammals, Uncategorized