Can wild animals tell days of the week?

Kind of a weird question, and I suspect the answer is “maybe some” or “it depends” but I’m wondering if wild animals are capable of recognizing the pattern of ebb and flow of human activity as it changes over the course of the week. For example, an animal living in a park might establish a habit of using a different hunting route on weekends when humans are present. But the question is, are they able to establish this as a pattern and anticipate the change, or just respond to waking up and seeing that the humans are out today. Certainly there are many temporal patterns that animals do respond to, such as seasons or phases of the moon. Are they capable of establishing new mental calendars, though?


Some animals do keep track of time and much more in various different ways, and it’s vital for them to perceive and respond to changes in season, weather, climate, local environment, etc. Re: calendar days, the concept is meaningful for animals too, although it might be thought of more in reference to a cycle of hours of sunlight and darkness or date in the season, etc. Sometimes animals don’t follow the exact calendar cycle, e.g. phenological dysregulation of some bees with their floral hosts due to climate change.


I think in general animals are able to exploit the everyday comings and goings of human activity to their advantage, but I don’t think they have an actual concept of “today is Monday, yesterday was Sunday” etc.

Urban activity in general seems to have some level of schedule to them, eg. market opens at 6am, shops close at 9pm etc, so it is possible that animals that are used to living in such habitats may exploit such cues to their advantage. But overall I feel that it is both, some may have some sort of schedule, others just take the chance (eg. gecko trying to catch something to eat under street light).

The final episode of Planet Earth II explores a few examples of how some species adapt to the urban habitat. It’s a fun watch.


That’s an interesting question. My daughter actually asked me something similar about deer. People like to feed the deer and it seems like on the weekend, when people tend to feed them the most, they’re all out, whereas during the week you’ll only see a few. I don’t know how they know or if they even do know but it’s definitely an interesting thing to think about.


Not days of the week no, but cycles of activity yes, in some animals, but not all.

This idea is called the "weekend effect hypothesis”, named after the 1998 Stalmaster & Kaiser paper titled Effects of Recreational Activity on Wintering Bald Eagles.

The study of this often falls under the heading of Behavioral Flexibility. Many of the studies of this deal more with long-term changes in behaviors (Gruber, et al 2019) or on changes like shifting the primary activity period from diurnal to nocturnal (Gaynor, et al 2019 - Smithsonian article here), but some studies have been done on the effects of weekly cycles and the results vary quite a bit by species.

Bautista, et al 2004 found that Spanish Imperial Eagles and vultures changed their behaviors during weekends, but other raptors did not, and similar changes are found across a wide range of species, although not uniformly within each genus. A study of bats in urban areas (Li, et al 2020) found changes in activity that appear to be linked to weekly cycles of human activity.

Other studies show that not all species are affected equally, and that some show no signs of change based on weekly human activity cycles, such as the Diniz, et al 2021 study on urban Rufous Hornero Furnarius rufus duets.

In short, it varies by species, with some being seemingly unaffected by weekly cycles of activity, and others being strongly affected by it. It appears that the reasons for the effects seen may be secondary ones, such as more nocturnal human activity on weekends meaning more areas lit up at night, which attracts insects in higher numbers, which bats then exploit, and similar chains of cause and effect.


Thank you for those links. It would be interesting to see a study that compares the activity on weekends vs. holidays (at least, the ones that generally have increased human activity) in species that exhibit a weekend effect. As it is, it seems equally possible that eg. bats are reacting and responding to the immediate presence of humans on weekends rather than forming a behavior pattern based on that weekly cycle. Since holidays break that pattern for humans, it would be telling to see the degree that wildlife follow. It looks like the only study that considered holidays was one that didn’t find evidence of a weekend effect in that species (Furnarius rufus)


In the park where I work there is a pair of ravens that hangs out in a big tree over the picnic tables on weekends. I see them there even when no one is at the picnic tables but I can’t swear they aren’t picking up on same-day human patterns rather than recognizing the seven day cycle.


I’d say it’s difficult to answer but could arguably be closer to yes for some animals. Although aside from that, the other details we each give may not be in any disagreement.

It depends on how days etc. are defined. All will be familiar with how many animals have an active period during each 24 hr cycle, mostly in day (daylight) aside from nocturnal/other species. In some ways that mere instinct to wake and behave affected by sunlight and darkness periods is like knowing days. Similarly, animals respond to environmental, weather, and climate cues which change over weeks, months, and seasons. Even the concept of human days, weeks, and months (for people) would probably be partly lost if a person were in an environment with no schedule or change in light and dark. Although, both people and many wildlife sleep during part of each 24 hr cycle too, which is also a concept of days (light-dark biological sleep cycle). Both humans and wildlife can be accidentally tricked/become deregulated if presented with sufficient misleading cues, or if they’re sick, etc. too.

Re: animal behavior/ethology, there are still some aspects being discovered, so I don’t consider ethology fully understood/complete yet. Each year, we learn some new “amazing” things animals (and even plants) can do. Somewhat analogous, I think of things like bird or bee foraging navigation or caching resources as requiring sophisticated temporal and spatial cognition. That said, I agree wildlife don’t know days “good enough,” and are at risk of being “tricked” by climate change-caused alterations to things like usual time of host plant bloom in a season.


A good bit of what you suggest is addressed in the papers I linked.

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Agreed! I have a habit of going to the park on holidays that people usually don’t spend at the park (Halloween, Thanksgiving, etc.) because I tend to see a lot of wildlife activity. But that’s far from a large scale quantitative study.


Could you ask this same question about people? Sometimes I think my body anticipates weekly patterns (say eating different on the weekends) but who knows if that’s because it’s a pattern or because there are other associated cues.


One of the things I find interesting about weeks is that unlike days, months, and years, they have no obvious astronomical basis. Why seven days? It is roughly a quarter of a month, but with no more basis than that I don’t imagine many things have natural seven day cycles.

I dunno, I’m not working and usually have no idea what day it is and see no difference between working days and weekends, even though I for sure lived in that cycle through bigger part of my life.


I’ve just found the book “The Seven Day Circle: The History and Meaning of the Week
By Eviatar Zerubave” on Google Books. I’ve only looked at the first several pages, but it reinforces the view that the seven day week is largely cultural and historical happenstance.

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My work is not centered around a weekend/weekday cycle and I generally have to check to see what day it is as well.

It’s just days, it’s not days of the week.


Because it is exactly one quarter of the 28-day lunar cycle. 28/4=7.

Some have proposed a 13-month calendar. If every month was exactly 28 days, there would be enough days left over for a 13th month, plus one extra day. One such proposed calendar is here: Law of Time Foundation

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In the introduction to the book I reference above, the author points out that the lunar cycle is close to 29.5 days, and that different cultures have divided this into three 10 day periods, three 9 day periods, four 7 day periods, five 6 day periods, or six 5 day periods. The fact that we prefer 28 is due to the 7 day week, not the other way around.


The fact remains, 13 months of 28 days each divides the year more evenly than any other configuration, having only the one extra day left over – called Day Out of Time.

I suppose you could divide the 365-day year into 73 weeks of 5 days each; but then you can’t have months of even length, because 73 is a prime number.

Three 10-day periods is a 30-day month, and that gives you 12 months, with 0.16 of a month left over, or 4.8 days. Same for six 5-day periods and five 6-day periods.

Three 9-day periods is a 27-day month. That gives you thirteen-and-a-half months in the year. What would you do with that extra half of a month?

Overall, I would say that a 28-day month made of exactly four 7-day weeks is the best attempt at coordinating the weeks and months into a coherent year.

and then we have leap years to tidy that bit that accumulates out of sync.

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