Between May of 1997 and August of 1998, Hare and Atkins studied alarm-calling in juvenile Spermophilus richardsonii (also called Richardson’s Ground Squirrels), namely how they react and treat those squirrels which issue “false-alarm” calls. A False-alarm call is one that is given when there is no predator nearby, and studies in other organisms have shown that the animals that “cry wolf” in those populations tend to be ignored by the others (even when they may be issuing an “honest” alarm call) if they have issued false alarms several times in the past.
To conduct this research, Hare and Atkins trapped, tagged, and gave a mark to each squirrel they captured, so that they could monitor their behavior. They took the juvenile squirrels and introduced them to a predator (a tan Biltmore hat) which made an appearance nearby whenever a recorded alarm call was played. They recorded and labeled the different alarm calls made by the young squirrels, and played them for the other juveniles, deciding randomly if they would be issuing a “false alarm” (no predator present) or an honest alarm (the Biltmore hat or a stuffed badger present). Callers designated “reliable” for some recipients (giving honest alarm calls) were then chosen to be “unreliable” (issuing false alarm calls) towards others.
In order to do these tests, they covered the stuffed badger with a blanket, and placed a camera on a tripod at a reasonable distance from the call recipient. If the call was to be honest, the blanket would be removed from the badger. If it was a false alarm, the blanket would remain on. They then ranked the squirrels response to the alarm call based on their attentiveness level. The four positions the squirrel’s gave were SD4: all four paws on the ground with the head down. SDU: all four paws on the ground with the head up. Slouched: two paws on the ground and the head down, and Alert: two paws on the ground with the head up.
Over several playbacks by unreliable squirrels, the recipient squirrels gradually reacted less when their calls were played, and assumed postures that were less alert. This is an important discovery, as previous to this research the only animals known to display this understanding of and behavior towards animals who “cried wolf” were humans and other primates.
Source: Hare, J., & Brent A. Atkins. (2001). The Squirrel That Cried Wolf: Reliability Detection by Juvenile Richardson’s Ground Squirrels (Spermophilus richardsonii). Behavioral Ecology and Sociobiology, 51(1), 108-112. Retrieved from http://www.jstor.org/stable/4602023
Eman Khwaja
November 9, 2017 — 1:18 am
It would be interesting to look at how the squirrels would react if the individual who gave the false calls suddenly gave real ones? And how quickly the other squirrels began to take the individuals with false calls seriously again.