I’m often asked that question, particularly in regards to parrots that have been or are being re-homed….will they forget previous situations or will their behavior be a constant challenge to a new owner? The answer is not at all simple, and no controlled scientific experiments have actually studied long-term memory in parrots.
In the laboratory, few studies examine avian memory beyond that of a few days’ time, at the most; the majority examine delays of only seconds or minutes. Some research on ravens, however, suggest they can remember the calls of various individuals for at least three years (Boeckle & Bugnyar, 2012); pigeons have been tested foronly up to about six months on memory for objects (Cook et al., 2005)—but no one knows how long their memories might really last.
Certainly, there are plenty of reasons to believe that parrots’ memories are as good as ours. A number of research papers now demonstrate that these birds have brain areas that function in ways very similar to the human cortex (Chakroborty et al., 2015; Jarvis et al. 2005, 2013; Olkawiciz et al, 2016; Gutiérrez-Ibáñez et al., 2018), that they have extremely high neural densities that enable advanced cognitive processing (which requires good memory; Olkawicz et al., 2016), and that even genomic similarities exist between parrot and human brains (Wirthlin et al., 2018). An ongoing study in my lab suggests that a Grey parrot has a visual working memory that outperforms that of young children and is mostly equivalent to that of adult humans (Pepperberg & Pailian, 2017).
Furthermore, many anecdotes exist that claim that parrots can remember situations, other parrots, and people over the course of their long lives. If you do an internet search, you will find many such instances. These instances can, just as for humans, be positive or negative. Thus there are heart-warming stories of parrots that have been reunited with owners after long-term separations.
Why Parrots Need to Remember
In the wild, parrots need to remember the location and navigational paths to food sources that may be available only once a year; thus the need for some form of long-term memory is clear. We also know that parrots that have been abused suffer from PTSD-like symptoms, and respond negatively to whatever situations or objects remind them of the abusive instances. Like humans, these birds can be de-sensitized with appropriate training and care over time. In the wild, memories for triggers such as rare predators could be life-saving; thus the evolutionary reasons for this form of memory are obvious.
What Do Pepperberg’s Parrots Remember?
My own experiences are limited to anecdotes, but support the ideas raised above. For example, fresh organic cherries are available for only a short period once a year, but their appearance would elicit an extremely clear “CHERRY” from Alex. As I’ve noted in a previous blog, Griffin and Athena sometimes produce what we call “hidden labels”—ones we’ve thought they either didn’t have or had forgotten—in similar appropriate situations. Notably, although we rarely mention anything about avian doctors in the day-to-day chatter in the lab, the words “veterinarian,” “vet,” or even my veterinarian’s name triggers anxiety behavior in Griffin and Athena; we have to refer to her as “she who must not be named.”
Griffin, and Alex before him, also seem to remember previous students over decades. Alex, who didn’t like strangers, always made exceptions for tall, blond men; we always wondered if a tall blond male had been involved in his hand-feeding. Griffin makes exceptions only for strangers who somehow demonstrate to him that they have lots of animal experience…so although he happily climbed onto the hands of my colleagues Frans de Waal and Thomas Bugnyar, new students may wait many weeks before he’ll accept them—but he remembers returning students without fail. [Athena, in contrast, likes everyone, probably because she has learned that new people will let her get away with things like chewing on their glasses or jewelry—behaviors that would trigger an immediate time-out from lab regulars.]
What I find of particular interest is how Griffin—and, again, Alex before him—seem to distinguish between student absences that are short versus long—the break point seems to be about six months. Thus students who have left for a long summer vacation will definitely get the “cold wing” upon their return, as I noted in an earlier entry. However, a student who has graduated and then returned after a prolonged absence will immediately be heartily and happily greeted! Last year, a student returned after a five-year absence, and Griffin acted as though it had been about five minutes.
We don’t know any logical reasons for these differences but of course we can anthropomorphize—maybe the “anger” at being abandoned lessens over time, to be replaced with “relief” at the re-appearance of a long-lost friend. In any case, it seems that we should assume that parrot memories are similar to ours, and expect that they will remember people, events, and objects that play important roles in their lives.
Boeckle, M, & Bugnyar, T. (2012). Long-term memory for affiliates in ravens. Current Biology, doi: 10.1016/j.cub.2012.03.023
Chakraborty, M., Walløe, S., Nedergaard, S., Fridel, E.E., et al., (2015). Core and shell song systems unique to the parrot brain. PLoS ONE 10(6): e0118496. doi:10.1371/journal.pone.0118496
Cook, R.G., Levison, D.G., Gillett, S.R., & Blaisdell, A.P. (2005). Capacity and limits of associative memory in pigeons. Psychonomic Bulletin & Review, 12, 350-358.
Jarvis, E.D., Güntürkün, O., Bruce, L., Csillag, A., Karten, H., Kuenzel, W., Medina, L., et al. (2005). Avian brains and a new understanding of vertebrate evolution. Nature Reviews Neuroscience, 6, 151-159.
Jarvis, E.D., Yu, J., Rivas, M.V., Horita, H., Feenders, G., Whitney, O., Jarvis, S.C., Jarvis, E.R., et al. (2013). Global view of the functional molecular organization of the avian cerebrum: mirror images and functional columns. Journal of Comparative Neurology, 521, 3614–3665
Gutiérrez-Ibáñez, C., Iwaniuk, A.N., & Wylie, D.R. (2018). Parrots have evolved a primate-like telencephalic-midbrain-cerebellar circuit. Scientific Reports (2018) 8:9960. doi:10.1038/s41598-018-28301-4
Olkowicz, S., Kocourek, M., Lučan, R.K., Porteš, M., Fitch, W.T., Herculano-Houzel, S., Němec, P. et al. (2016). Birds have primate-like numbers of neurons in the forebrain. Proceeding of the National Academy of Sciences, USA, 113, 7255–7260.
Pepperberg, I.M., & Pailian, H. (May 24, 2017). Evolution of mechanisms underlying visual working memory manipulation: when “bird-brain” is a compliment. Vision Science Society, FL
Wirthlin, M., Lima, N.C.B., Guedes, R.L.M., Soares, A.E.R., et al. (2018). Parrot genomes and the evolution of heightened longevity and cognition. Current Biology, doi:10.1016/j.cub.2018.10.050.