Many wild animals hold a private piece of land or territory that they rigorously defend against intruders. Having good neighbours that respect territory boundaries means less work and stress for territory owners – but some neighbours may be better than others, new research has revealed.
Scientists studied a population of Seychelles Warblers, a small island Acrocephalus warbler endemic to the Seychelles islands in the Indian Ocean, to test whether territory owners with more related or more familiar neighbours had the most peaceful territories and better health as a result. They found that while territory owners were sometimes observed fighting with their neighbours, this was never with family members or neighbours they had lived next to in previous years.
Researchers then measured the birds’ body condition and telomere length, these being sections of DNA that protect an individual’s genetic material but which erode faster during times of stress and poor health. Territory owners that had more relatives or familiar neighbours were in better condition and showed less telomere loss. If new or unrelated neighbours moved into the area, territory owners lost condition and suffered more telomere shortening.
Since telomere loss is a measure of how quickly an animal is ageing and may also predict how long that animal will live, the results show just how important good neighbours can be. The scientists also found that the effect of having related or familiar neighbours was more important in densely populated areas, where the number of neighbours (and hence the number of borders to maintain) is higher.
Lead author of the research, Kat Bebbington of UEA’s School of Biological Sciences, said: “Defending territory boundaries is crucial if animals are to hold onto valuable food and other resources. Territory owners [that] are constantly fighting with neighbours are stressed and have little time to do other important things such as finding food and producing offspring, and their health suffers as a result.
“Interestingly, we show that it’s not just relatives that can be trusted, but also neighbours you get to know well over time. Something similar probably occurs in human neighbourhoods: if you’ve lived next to your neighbour for years, you are much more likely to trust each other and help each other out now and then.”
In a world where wild animals are increasingly squeezed into small areas of natural habitat, understanding how relationships between neighbours affects the health and lifespan of individuals is crucial. The discovery that territory owners can benefit from living next to relatives or familiar neighbours provides new information about how conflict over space and resources can be resolved, the researchers said.
Bebbington, K, Kingma, S, Fairfield, E, Dugdale, H L, Komdeur, J, Spurgin, L, and Richardson, D S. 2017. Kinship and familiarity mitigate costs of social conflict between Seychelles warbler neighbour. Proceedings of the National Academy of Sciences of the United States of America (PNAS). In Press.