Sociality helps mitigate anthropogenic risks: evidence from elk crossing a major highway

Phenotypic variation among individuals scales up when they associate with
others, creating variation within and among groups that can shape
group-level outcomes such as when and where groups move. While sociality
is thought to be a fitness rewarding behavior, empirical evidence
supporting how it influences individual behavior and the resulting fitness
consequences (e.g., risk experienced) remains limited, especially in the
context of human-modified landscapes. Here, we use empirical observations
to test whether sociality helps animals cross busy roads. Our data came
from free-ranging elk in a population where > 75% of the adults
were tracked, and in which group size and composition were highly
variable. We combined field observations with GPS collar data to quantify
four social phenotypes of individuals and groups: dominance (initiation of
successful agonistic interactions), social connectedness (number and
connectedness of social associates), social familiarity (frequency of
association with group members in the past), and social stability (time
since fusion with group members). We then investigated how these four
social phenotypes influenced an individual's probability of crossing
a major highway, and tested if particular social phenotypes made better
road crossing decisions (i.e., crossed at lower traffic volume). We found
that who is in a group shapes the behavior of group members around
anthropogenic risks. Individuals in groups that were more dominant, more
connected, and to a lesser extent more familiar had a lower probability of
crossing the highway. Individuals that had spent more time with group
members had a higher probability of crossing the highway. Importantly, our
results suggest that sociality plays a role in safe movements around
anthropogenic risks. Individuals in highly connected and familiar groups
were less likely to cross the highway at high traffic volume. Our work
provides empirical evidence that sociality influences the movements of
group-living individuals through anthropogenic disturbances, and helps
individuals mitigate the risks associated with such disturbances.
Developing a comprehensive understanding of animal sociality in
human-modified landscapes is especially important as social behaviors are
simultaneously threatened by human disturbances, which could be
particularly detrimental for group-living species if those same behaviors
help individuals mitigate risks.