It’s one of the oldest questions in the book—fight or flight? A new study by a research fellow at the University of Cambridge suggests the answer is more complicated than previously thought for the iconic finches of the Galapagos Island. The answer also has human-induced roots.
In a surprising result, finches on some of the Galapagos Islands still showed anti-predator behavior (e.g. flight initiation distance, or FID) more than a decade after the eradication of human-induced predators.
The Galapagos Islands are a unique research bed for comparison studies as some islands have never had invasive predators, some currently have human-introduced predators like cats and rats, while still others had predators in the past that have since been eradicated. A single location with three different predator situations is a gold mine for a zoologist like Kiyoko Gotanda, who is the sole author of the paper recently published in the Journal of Animal Ecology.
“This, coupled with the different sizes of permanent human populations (urbanization) makes it an excellent place to study the effects of different human influences on anti-predator behavior,” Gotanda told Laboratory Equipment.
In the study, as expected, Gotanda found that finches on islands with predators were wary, and flew away from perceived danger (e.g. a researcher imitating a predator) at a much greater distance than the finches on pristine islands without predators. However, this increased anti-predator behavior was also seen on islands where invasive predators were successfully eradicated in 2003 and 2008—and that was shocking.
“The surprising results suggest that whatever influences this fearful behavior is more complicated than just the presence or absence or invasive predators,” said Gotanda.
This is one of the first studies to show that anti-predator behavior has been maintained on islands that have had invasive predators removed. In her paper, Gotanda proposes five possible explanations for the oddity:
- Increased anti-predator behavior has evolved on islands that have and used to have invasive predators. While the normal lifespan of finches ensure these birds are not the ones who encountered predators on the island, Darwin’s evolution theory may have come into play at the very place he first discovered it.
- The expected costs of increased anti-predator behavior are not high enough to cause a reversion to pre-predator levels. It could also be that not enough time has elapsed for reversion in anti-predator behavior.
- The previously published “multi-predator” hypothesis suggests increased anti-predator behavior lingers due to remaining local and endemic predators. Gotanda, however, believes this scenario is unlikely in her study, given that she has proven finches have lower anti-predator behavior on islands with no history of invasive predators. Therefore, it is a different mechanism that is maintaining the increase in anti-predator behavior.
- Increased FID could be passed from generation to generation as a learned behavior.
- The increase in FID could be due to something other than predation (e.g., parasitism, life history, or habitat) that could still be present on eradicated islands. Or, for unknown historical reasons, anti-predator behavior on the eradicated islands have been, unknowingly, historically high.
“Quantifying FID and understanding the mechanisms behind such anti-predator behavior can help us understand how organisms perceive potential threats and how they might adapt to different human influences. In this case, we know that finches can adapt to the presence of invasive predators by increasing their anti-predator behavior. This increase in FID could be energetically costly, so from a conservation management perspective, you could consider options to help mitigate the costs of increased anti-predator behavior,” Gotanda explained.
“The time and energy finches spend spooking themselves by fleeing when they are not in danger could be better spent looking for food, mating, laying eggs, and rearing their young.”
Gotanda is continuing her research by looking into the effects of urbanization on other behaviors, such as neophobia, in an attempt to better understand individual behavioral variation. Additionally, she plans to research the finches’ physiological responses to urbanization.