Yellow-bellied marmots, Marmota flaviventris, are adorable tubby rodents who live in burrows fortified by slopes and rock outcroppings in the western U.S. and Canada. When predators approach, the marmots that sound the alarm for their colony risk becoming a conspicuous target. However, they could also benefit from alerting others, if that increases their social status or if that kind deed is reciprocated later on. The costs and benefits of alarm calling among social rodents are well documented, but few studies have examined how social standing influences the tendency to emit these calls.
To see if an individual marmot’s social position affects how often it will loudly alert others, a team of researchers from the University of California, Los Angeles, led by Daniel Blumstein studied and tagged marmots from six colonies; examining their social attributes, such as how embedded and influential they are in their colony. The team jotted down each friendly encounter (from nose bops to playful scuffles), Science reports, in order to reconstruct the social network, linking 142 marmots living near the Rocky Mountain Biological Laboratory in Colorado. Then they rated the marmots by popularity and relationship strength and plugged those into a model to explain how the natural rate of alarm calling relates to social positioning.
The marmots who called out the most frequency were the least popular, and therefore not the highest standing marmots. These are the loner marmots who have fewer connections than others in their marmot social network. The team also looked at the rate of trap-induced calls -- that’s when a marmot is actually in a trap, facing what they might think is an imminent personal threat. Marmots with weaker relationships made trap-induced calls more often.
The findings, published in Behavioral Ecology this month, refutes the reciprocity hypothesis. Unpopular marmots could be trying to up their social status by calling, and trapped marmots with weaker relationships can’t rely on others to call.