A Food for All Seasons: Stability of Food Preferences in Gorillas across Testing Methods and Seasons

Abstract

Decisions about which foods to use during training and enrichment for captive animals may be based on invalid assumptions about individuals’ preferences. It is important to assess the stability of food preferences given that one-time preferences are often used to inform which items are offered over a longer period of time. Presenting preference assessments using images of food items allows control over factors such as size, scent, and inadvertent cueing but requires validation. We presented three male gorillas with choices between randomly selected pairs of actual food items from their morning meal using PVC feeders. We also presented the gorillas with two-alternative forced-choice tests between images of these foods on a touchscreen computer. Ranked preferences were correlated across method and seasons. Furthermore, gorillas selected images of preferred over less preferred foods in a validation task on the touchscreen. However, selections of some food items changed within sessions, suggesting that preference may be relative to other contextual factors. Researchers should assess how choices affect subsequent preferences to understand whether animals demonstrate absolute preferences for particular food items, or prefer variety.

Prosocial or photo preferences? Gorillas' prosocial choices using a touchscreen

“…Given the number of species that show evidence of picture object recognition (reviewed in Fagot, 2000), and our own previous research with gorillas, we find it unlikely that they are unable to perceived photographs as representing real objects. For instance, our study of food preferences (Vonk, Truax, et al, 2022) revealed consistency in these gorillas' preferences whether they were pointing to actual foods or selecting images of foods on the touchscreen. Other studies of food preferences corroborate the finding that gorillas' responses to images presented on a touchscreen reflect their food preferences (Huskisson et al, 2020, 2021).…”

“…For instance, our study of food preferences (Vonk, Truax, et al, 2022) revealed consistency in these gorillas' preferences VONK | 15 of 18 whether they were pointing to actual foods or selecting images of foods on the touchscreen. Other studies of food preferences corroborate the finding that gorillas' responses to images presented on a touchscreen reflect their food preferences (Huskisson et al, 2020(Huskisson et al, , 2021.…”

Potential Food Inclination of Crab-Eating Macaques in Laboratory Environments: Enhancing Positive Reinforcement Training and Health Optimization

“…Additionally, potential food inclination and the consistency of potential inclination were evaluated through multiple offerings, and the necessity for diverse food provision was assessed. Evaluating the stability of potential food inclinations is helpful for recognizing potential inaccuracies associated with preferences [37]. The findings of the present study could enhance our understanding and facilitate the improvement of experimental and husbandry practices for NHPs, in addition to the enhancement of the welfare of NHPs.…”

Applied behavior analysis and the zoo: Forthman and Ogden (1992) thirty years later

“…Preference assessments have also been used to investigate concepts such as preference for novelty (Addessi et al, 2005 ), variety (Addessi, 2008 ; Addessi et al, 2010 ), work/contrafreeloading (Sasson‐Yenor & Powell, 2019 ), or choice (Perdue et al, 2014 ). Preference stability across time has also been investigated (Addessi et al, 2010 ; Clay et al, 2009 ; Hopper et al, 2019 ; Martin et al, 2018 ; Vonk et al, 2022 ). All these findings can be used to guide animal management practices to optimize welfare (see Broom & Johnson, 2019 ).…”