Nutty for Colour

Hi, I’m Kira, and my family and I love squirrels—but have you ever dealt with them raiding your bird feeder?

Me too! That made me wonder…are squirrels influenced by COLOUR?

Eastern grey squirrels, native to eastern North America, can clearly see blue and yellow…but red and green appear more greyish or brownish.

Dogs have similar vision, and studies show they’re more attracted to colours they can see well (Video: Oshies World, 2020), which is why many dog toys are blue and yellow!

Thus… does this apply to squirrels?

To test this, I placed five identical pots - red, yellow, green, blue, and grey under controlled conditions in my backyard. Over 50 trials, I recorded the order in which squirrels approached each colour.

Interestingly, there were clear differences in colour preference, suggesting that colour does influence squirrel behaviour!

As a result, red and yellow forage toys could be used in wildlife rehabilitation to encourage squirrel engagement (Video: Brasch, 2016), or if you're wanting squirrels to raid your bird feeder less… get a grey one!

My family has loved squirrels ever since moving to Canada, and we enjoy watching them forage, chase, and be adorable in our backyard. Nonetheless, we still had to deal with them raiding our bird feeder.

This curiosity developed into my research question: Does changing the colour of an object make it more attractive to squirrels and cause them to approach it more based on their dichromatic vision?

Eastern grey squirrels (Sciurus carolinensis) have dichromatic vision, meaning they have two types of cones in the back of their eyes, which are specialized photoreceptor cells responsible for detecting colour (Wildlife Online, 2020) (Figure 1). This allows them to distinguish blue and yellow hues well, but makes it difficult for them to differentiate red and green, similar to red–green colour blindness in humans (Figure 2). In contrast, humans typically have trichromatic vision, with three types of cones that allow us to perceive a wider range of colours (Cleveland Clinic, 2024).

Other animals, such as dogs, also possess dichromatic vision (Fernandez & Morrison, 2026) (Figure 3). Research has shown that dogs are more attracted to blue and yellow objects, helping companies design and pet owners choose more visually engaging toys (Happy Staffy Co., 2025) (Figure 4).

Based on this, I hypothesized that squirrels would investigate blue and yellow objects more frequently, since their vision is similar to dogs, which respond more strongly to these colours. Overall, this project was inspired by personal curiosity and a real-world problem, exploring how colour may influence animal behaviour.

I conducted my experiment using five identical 2.5-inch terracotta pots, each painted a different colour: red, yellow, green, blue, and grey, with grey as the neutral control (Figure 5).

Research conducted at the University of Exeter by I. M. V. MacDonald (1997) found that squirrels could sometimes discriminate between red and green biscuits. However, later analysis suggested that this response may have been influenced by brightness and scent rather than true colour vision (Wildlife Online, 2020), highlighting the importance of carefully controlling these variables.

To control for brightness, a lux meter app was used indoors under consistent lighting conditions (Figure 6). Any pots showing outlying brightness values were repainted and re-measured until all colours were within 5–10% of each other, ensuring colour rather than brightness influenced behaviour.

To control for scent, each pot was coated with Mod Podge, a clear sealant allowing them to be cleaned between trials (Figure 7). This was important because squirrels have scent glands that produce markers for communication and recognition, which can influence how other squirrels interact with the same objects (Dowd, 2016). To further reduce contamination, hands were washed with unscented soap and disposable gloves worn when handling materials.

Pots were placed outdoors in a straight line in a location with frequent squirrel activity, spaced equally apart (Figure 8). Each pot contained one unsalted, unflavoured peanut to encourage interaction. To reduce positional bias, pot order was randomized for each trial. Each session was recorded for accurate observation. Two 60-minute trials were conducted daily at 7:30-8:30 a.m. and 3:30-4:30 p.m., without disturbance. After each trial, pots were cleaned and stored in a box in a low-scent area.

In total, the order squirrels approached the pots was recorded as a measure of colour preference over 64 trials.

According to the 50 valid trials out of 64 conducted, pot colour influenced the order in which squirrels approached the pots, with clear differences in approach behaviour observed across different colours. The remaining 14 trials were excluded from analysis because no squirrels appeared during the 60-minute observation period, and therefore no approach behaviour could be recorded. Across the experiment, seven individual squirrels repeatedly visited the setup (Figure 9).

First-choice selection proportions were used as the primary measure of squirrel colour preference (Figure 10), representing initial decision-making behaviour. Red (32%) had the highest proportion of first-choice selections, followed by Yellow (26%), while Grey (8%) had the lowest.

Mean preference scores were also calculated using a point-based ranking system (Figure 11), where the first pot chosen received 5 points, second 4, and so on. Red (3.54) and Yellow (3.48) received the highest average scores, while Blue (2.88), Green (2.86), and Grey (2.28) were lower overall.

A one-way ANOVA was conducted on the point-based data. The results showed a statistically significant difference between groups (p = 0.000012, p < 0.05), indicating that the observed variation in colour response is unlikely to be due to chance. ANOVA compares differences between groups (average scores for each colour) with the natural variation within each group (differences in squirrel behaviour across trials). In this case, differences between colours were larger than the variation within groups, suggesting the results were not random.

In conclusion, changing the colour of an object influenced squirrel interaction, shown by differences in mean first-choice selections and preference scores across the coloured pots. However, the original hypothesis that squirrels would prefer blue and yellow based on dichromatic vision alone was not supported, although colour clearly affected behaviour. Instead, red and yellow pots received the highest levels of interaction, while grey received the lowest.

Based on these results, practical applications may include red and yellow forage toys being used in wildlife rehabilitation centres to encourage activity and recovery in squirrels (Figure 12). Conversely, grey coloured objects may be less likely to attract attention and could potentially be used in contexts where reduced squirrel interaction is desired, such as for bird feeders to help keep squirrels away (Figure 13).

Further efforts could:

-Examine preference for warm over cool colours, as higher interaction with red and yellow compared to blue and green may indicate a broader colour-category preference rather than colour vision alone (Figure 14)

-Use different food types (e.g., seeds instead of peanuts) to better reflect bird feeder conditions (Figure 15)

-Repeat experiment across different seasons, as these trials were conducted from September–December, and seasonal behaviours (e.g., food caching in fall vs. retrieval in spring) may affect squirrel activity and preferences (Figure 16)

-Increase number of trials to improve reliability

Thank you to the dedicated Waterloo-Wellington Science & Engineering Fair delegates for their ongoing guidance, and to the WWSEF donors for generously supporting my trip to CWSF.

Special appreciation goes to my exceptional teacher, Ms. Bolliger, for inspiring my science fair journey, and to my phenomenal librarian, Ms. Harrison, for her insight, patience, and continuous support throughout this project.

I am grateful to my family for providing access to camera equipment and a backyard space to conduct my experiment.

Finally, thank you to the adorable squirrels who unknowingly participated in this study and were well fed in preparation for winter.

Research:

Chow, Pizza Ka Yee, et al. “Touch Screen Assays of Behavioural Flexibility and Error Characteristics in Eastern Grey Squirrels (Sciurus Carolinensis).” Animal Cognition, vol. 20, no. 3, Jan. 2017, pp. 459–71, https://doi.org/10.1007/s10071-017-1072-z.

Cleveland Clinic. “Color Blindness: Causes & Information.” Cleveland Clinic, Cleveland Clinic, 30 Dec. 2020, my.clevelandclinic.org/health/diseases/11604-color-blindness.

---. “Photoreceptors (Rods and Cones).” Cleveland Clinic, 5 June 2024, my.clevelandclinic.org/health/body/photoreceptors-rods-and-cones.

Coren, Stanley. “What’s Your Dog’s Favorite Color?” Psychology Today, 2025, www.psychologytoday.com/ca/blog/canine-corner/202504/which-colors-do-dogs-prefer.

Dowd, Bill. “How Squirrels Mark Their Territory.” Skedaddle Humane Wildlife Control, 26 Apr. 2016, www.skedaddlewildlife.com/blog/how-squirrels-mark-their-territory/.

Fernandez, Christina, and Barri Morrison. “What Colors Can Dogs See?” Petmd.com, PetMD, 2026, www.petmd.com/dog/general-health/what-colors-can-dogs-see.

Hamilton, Heather. “Eastern Grey Squirrel - Hinterland Who’s Who.” Hinterland Who’s Who, 2025, www.hww.ca/wildlife/mammals/eastern-grey-squirrel/.

Happy Stappy Co. “What Colour Toys Are Best for Dogs?” Happy Staffy Co., 2025, www.happystaffyco.com/blogs/news/what-color-toys-are-best-for-dogs.

MACDONALD, I. M. V. “Field Experiments on Duration and Precision of Grey and Red Squirrel Spatial Memory.” Animal Behaviour, vol. 54, no. 4, Oct. 1997, pp. 879–91, https://doi.org/10.1006/anbe.1996.0528. Accessed 2 Sept. 2019.

Mueller, Marcus. “Can Squirrels See Colors?” Skedaddle Humane Wildlife Control, 5 Mar. 2020, www.skedaddlewildlife.com/location/milwaukee/blog/can-squirrels-see-colors/.

University of Guelph. “Local Squirrel Study Invites Community Participation.” U of G News, 14 June 2016, news.uoguelph.ca/2016/06/local-squirrel-study-invites-community-participation/.

Wildlife Online. “Squirrel Behaviour - Scent-Marking .” Www.wildlifeonline.me.uk, 15 Aug. 2019, www.wildlifeonline.me.uk/animals/article/squirrel-behaviour-scent-marking.

---. “Squirrel Senses.” Wildlifeonline.me.uk, 2020, www.wildlifeonline.me.uk/animals/article/squirrel-senses.

Images/Videos:

Abrantes, Roger. “The Human’s View vs the Dog’s View.” Ethology Institute, 2014, ethology.eu/the-dogs-color-vision-and-what-it-means-for-our-training/.

Baldwin, Marc. “A Grey Squirrel (Sciurus Carolinensis) Caching a Nut in the Lawn.” Wildlife Online, 2021, www.wildlifeonline.me.uk/animals/article/squirrel-food-feeding-larders.

BC SPCA. “What You See. What Your Dog Sees.” BC SPCA, 2022, spca.bc.ca/news/how-dogs-see-colour/.

Colour Blind Awareness. “Normal Vision vs Protanopia.” Colour Blind Awareness, 2026, www.colourblindawareness.org/colour-blindness/causes-of-colour-blindness/.

Dreamstime. “Squirrel with Glasses Reading a Book in a Library Setting .” Dreamstime, 2026, www.dreamstime.com/squirrel-glasses-reading-book-library-setting-surrounded-bookshelves-charming-wearing-intently-reads-cozy-shelves-image383428040.

Egete, Kira. Personal photographs, 2025.

Feng, Xuping. “How Animal Vision Differs from Human Vision.” BRINTYE, 2025, brinytestore.com/blogs/brinyte/how-different-light-colors-affect-hunting-success.

Franke, Luke. “Clockwise from Top Right: Bird-Specific Seed Blend; High-Energy Blend; Anti-Squirrel Blend; Bird-Excluding Blend; No-Mess Blend.” Audubon, 2023, www.audubon.org/magazine/mixology-breaking-down-5-common-birdseed-blends.

Greenwood Wildlife. “Found a Squirrel.” Greenwood Wildlife, 2023, www.greenwoodwildlife.org/wildlife-emergency/i-found-an-animal/found-a-mammal/found-a-squirrel/.

Newman, Mark. “Arizona Gray Squirrel.” Birds&Blooms, 2026, www.birdsandblooms.com/birding/attracting-birds/feeding-birds/squirrel-proof-bird-feeders/.

Oshies World. “Golden Retriever Plays with Squeaky Toy | Oshies World.” Youtu.be, 7 Apr. 2020, youtu.be/M2eXaRFq7Wo. Accessed 29 Apr. 2026.

Sam Brasch. “Baby Squirrel Eating.” YouTube, 13 Oct. 2016, www.youtube.com/watch?v=PBeM2wYZOdw.

Umbra. “Umbra Bird Cafe Bird Feeder.” Amazon, 2026, www.amazon.ca/Umbra-Caf%C3%A9-Bird-House-Grey/dp/B09KV5TWXJ.

Webster, Katie. “Colour Wheel.” A Season for Home, 2025, aseasonforhome.com/warm-colors-vs-cool-colors-what-is-the-difference/.