Impacts of predation risk on learning and memory of free-living mice
Abstract
In predator-prey interactions, responses to predation risk typically involve behavioural, morphological, or physiological changes. Laboratory-based studies have also shown changes in prey cognition (i.e., learning and memory), with individuals often showing impairment. However, an ecological perspective predicts that wild animals should conserve their cognitive ability, given that many risk responses require robust cognition. Here, we simulated predation risk and used a field-adapted version of the Morris Water Maze (MWM), to investigate how chronic predation risk affects cognition in wild white-footed mice. We found that 24d exposure to predation risk did not impair learning. However, those exposed to risk had a 25% reduction of short-term memory. Twelve days post risk exposure, we found no performance differences between risk-exposed and control mice. Additionally, risk-exposed mice displayed greater exploration with a higher probability of completing the MWM in their initial trial. Given that prey integrate multiple pieces of information to shape their behaviour, the lack of learning impairment and altered exploration strategies may help mice respond to predation risk. However, the tendency of memory impairment suggests there are consequences to cognition when experiencing increased predation risk.
README: Impacts of predation risk on learning and memory of free-living mice
Data for free-living white-footed mice (Peromyscus leucopus) under chronic predation risk simulation. This project was conducted in the Southeastern Massachusetts Bioreserve, USA. We used auditory playbacks to simulate predation risk (or no sound for controls) and a field-version of the Morris Water Maze (MWM) test to investigate how predation risk affects cognition (i.e., learning and memory) in free-living mice. Auditory playbacks were broadcast for 3 weeks, in a 4-day-on 4-day-off schedule. All methods in this study were approved by our Universities IACUC (IACUC 22-02) and followed guidelines of the American Mammalogy Society.
Contact Carolina Ganci (cganci@umassd.edu) with any questions. This manuscript has been accepted for publication (01/03/2025) at Proceedings of Royal Society B.
Ganci CC, McKay L, Hunninck L, Sheriff MJ. Impacts of predation risk on learning and memory of free-living mice. Proc. R. Soc. B (accepted). 10.1098/rspb.2024.1978
R script associated with this file can be found under the name "RScript.R" or through the link:
https://doi.org/10.5281/zenodo.14713127
The R script includes the data file "data.csv", code version, as well as all the instructions and necessary packages used to do the analysis.
Data files included:
data.csv
This file (data.csv) contains data on P. leucopus' performance on MWM, as well as additional data on individuals' ID, sex, weight, treatment and capture event. The data consists of 13 variables, all collected by the authors during the summer of 2020.
1. tagID: unique ID number per individual mouse
2. day: experiment stage; 3 levels; pre = trapping before the treatment was in effect, during = trapping while the treatment was in effect, post = trapping after the treatment was completed (see manuscript for more info)
3. date: date of mouse capture
4. grid: mice were trapped on 6 grids, each belonging to either control or predator treatment
5. trial: indicating the ID of each trial (from 1 through 6)
6. time: time in seconds spent during each trial to find the platform (see manuscript for more details on the Morris Water Maze) <!-- Note that when a trial failed, no time was recorded (variable "time" = NA), however we still recorded a distance traveled (variable "dist"). -->
7. dist: distance traveled in meter during each trial
8. weight: weight in grams of each mouse
9. sex: sex (male or female) of each individual mouse
10. trial_success: indicates whether the trial was successful (1) or not (0)
11. treatment: indicates whether mouse came from a grid with treatment (predator) or no treatment (control)
12. cap_event: indicates whether on this occasion, this was the first, second, or third capture of a single individual
13. day_since_last_cap: number of days since last capture (0 if 'cap_event' is 1)