Conditional syndromes: Effect of human disturbance and age on the correlation between flight initiation distance and vigilance in marmots

Abstract Behavioral syndromes—suites of correlated behaviors across different situations and contexts—are widespread and can have important ecological consequences because correlations between distinct behaviors shape how animals respond to changing environmental conditions and can limit behavioral plasticity. Behaviors such as vigilance, foraging, and exploration are correlated in many species and thus constitute a syndrome. Studying the structure of such syndromes is important to understand potential constraints on an animal’s behavioral response to the environment. Importantly, we know relatively little about antipredator behavioral syndromes and how their structure is associated with environmental conditions. Here, we estimated the correlation between two antipredator behaviors in yellow-bellied marmots ( Marmota flaviventer ): flight initiation distance (FID), which quantifies the flightiness of an animal in response to a potential predator and time allocation to vigilance while foraging, which represents an individual’s baseline level of wariness. We also examined the correlation between these traits under two different human disturbance levels by fitting a bivariate model on data collected over 18 years from 739 individuals. We found a modest positive among-individual correlation between FID and vigilance in adults, but no correlation between those variables in the much larger yearling cohort, nor when datasets for yearlings and adults were combined. We found no support for the hypothesis that human disturbance changed the structure of the syndrome (when present). Our study suggests that antipredator syndromes may be age-specific, and thus constraints on the independent expression of the behaviors underlying those are age-specific as well.