Background/Question/Methods Previous research indicates that individuals in urban environments are bolder than their rural conspecifics and display strong within-individual consistency in this boldness. During initial contact with urban environments high diversity of behavior types within a population allows expansion and growth into novel habitat. Over time behavioral diversity will decline if some behavior types are more successful in this new environment, leading to a more homogenous distribution of behavior types within an urban population. Anolis lizards provide an ideal study system for understanding traits driving success of invasive species in urban habitats. In this study we assess 1. Whether a boldness syndrome exists in brown anole lizards (Anolis sagrei) on the island of Oʻahu and 2. Whether urban populations are, on average, bolder than rural populations. We performed behavioral assays on free-ranging animals in the field at eight sites throughout Honolulu, Oʻahu. We measured structural habitat characteristics, human activity, bird abundance, prey abundance, and lizard density to quantitatively characterize an urban-rural gradient. Across the eight sites we caught and marked over 650 lizards, allowing us to resight and perform assays on 279 individuals.
Results/Conclusions An intraclass correlation coefficient indicates that within-individual behavioral consistency exists but is weak (ICC = 0.14, 95%CI = (0.069, 0.22)), while a mixed model approach similarly found that lizard ID explained a modest 24% of the variance in behavior. We observed a weak, non-significant trend towards increased boldness in urban lizards. Whether large or small individuals were bolder depended on sex: for females the largest individuals were half a standard deviation bolder than small individuals, while for males the smallest individuals were a standard deviation bolder than large individuals. While this study demonstrates that a boldness syndrome exists in A. sagrei on Oʻahu, there does not appear to be a difference in behavioral responses in urban and rural populations. The introduction of A. sagrei to Oʻahu is relatively recent. Lizards are still activley spreading into new habitats potentially favoring mixed populations rather than monocultures of only bold or shy lizards. Additionally, as there is evidence for a link between genetics and behavioral syndromes, founder effects paired with migration between adjacent urban and rural sites could account for low variation in boldness across sites.
