Abstract
In the Galapagos, humans have established a permanent presence and have altered selective pressures on local and endemic species through influences such as invasive predators and urbanization. I quantified flight initiation distance (FID), an antipredator behaviour in Darwin’s finches, across multiple islands in the Galapagos to address two questions: (i) does antipredator behaviour change in the presence of invasive predators and importantly, what happens once invasive predators have been eradicated and (ii) to what degree does urbanization affect antipredator behaviour? The Galapagos Islands offers a system of among island differences in invasive predator regime as well as degree of urbanization presenting an opportune place to answer these two questions. Furthermore, this is one of the first studies to look at behaviour in an endemic species after successful eradication of invasive predators. FID was higher on islands with invasive predators as compared to islands with no predators. On islands from which invasive predators were eradicated ∼11 years previously, FID was also higher than on islands with no invasive predators. Within islands that had both urban and non-urban populations of finches, FID was lower in urban finch populations, but only above a threshold human population size. FID in larger urban areas on islands with invasive predators was similar to or lower than FID on islands with no history of invasive predators. Overall, these results suggest that for antipredator behaviour, invasive predators can have a lasting effect on antipredator behaviour, even after eradication, and that the effect of urbanization can strongly oppose the effect of invasive predators, reducing antipredator behaviour to levels lower than found on pristine islands with no human influences. Together, we can begin to understand how human influences are affecting antipredator behaviour which could help inform future conservation and management efforts on islands.
“All of [the terrestrial birds] are often approached sufficiently near to be killed with a switch, and sometimes, as I myself tried, with a cap or a hat.” – Charles Darwin in “The Voyage of the Beagle”