• Julia RIley

City-living favours the bold toad

In our recent study published in Behavioural Ecology and Sociobology, myself and colleagues investigated the behaviour of Guttural Toads in urban and natural areas in Durban, South Africa (within their native range) and in their invasive range (in Mauritius and Reunion). We wanted to investigate whether toads in urban areas express different behaviour than toads from natural areas, and whether this may have aided in their invasion into these novel environments. In each location we recorded toad exploration and boldness in our field lab. The invasion pathway is known for these toads, so we were able to see if these behavioural traits change along their invasion route.


We found that differences in toad exploration were not directly related to their invasion pathway but was lower in toads from Mauritius. On the other hand, toad populations were bolder in urban areas in their native range and this increased boldness persisted in the other urban areas within their invasive ranges. Interestingly, toad boldness reverted back to natural-native levels in populations that spread into natural areas on both islands.


The differences we found in boldness across their invasion pathway support the growing idea that anthropogenic landscapes favour bolder individuals, as well as the assertion that urban-derived traits may bolster a species' ability to establish and spread in novel landscapes and promote their invasion success.


A Guttural Toad (Sclerophrys gutturalis) in an urban garden.


A great blog was written about this study by James Baxter-Gilbert and can be found on the Centre of Excellence for Invasion Biology's website here: https://blogs.sun.ac.za/cib/urban-toads-show-themselves-to-be-bolder-before-and-after-invasion/


Check out the article here and this is its citation:

Baxter-Gilbert J, Riley JL, Measey J (2021) Fortune favors the bold toad: urban-derived behavioral traits may provide advantages for invasive amphibian populations. Behavioural Ecology and Sociobiology 75: 130.