Creature Feature: California Scrub Jay

Many a morning here in Davis, California begins with a loud “SKERAWK!” that pierces the ear drums and can disturb even the deepest of sleepers, followed by the rustling of branches and the quick scuttling of squirrel feet across roof panes. Such a hubbub wakes me up nearly daily, and I can assuredly open the window to find an inquisitive blue-headed and gray-breasted bird looking at me, threatening to screech once again. This natural alarm clock service is provided by the California scrub jay (Aphelecoma californica), which is, as its name suggests, a bird that is widespread across the state.  Throughout the day, I notice scrub jays hopping around the UC Davis campus, and think to myself that they would make an excellent mascot, second only to the campus cows.

If I had to make a case for nominating the scrub jay for Davis mascot, I would argue that like UC Davis’ students and researchers , scrub jays are smart. This will come as no surprise to avid readers of this blog and well-versed animal behaviorists, because we’ve long learned that “bird-brained” is an unfortunate and inaccurate insult to avian species. But even compared to other birds, scrub jays land in the top percentile.  Scrub jays belong to a family of birds called corvids, which includes crows, ravens, magpies and other jays, like blue jays. The corvids are infamous for their intelligence among birds.  Crows understand water displacement, can recognize human faces, and can use tools; magpies can mimic human voices in disturbingly eerie ways.  Among their peers, perhaps scrub jays don’t appear quite as impressive. But they do have some unique skills to bring to the corvid table.

scrub_jay_seeds
A California scrub jay stuffing its face with seeds, likely to cache them. [Source]
Many of the scrub jay’s skills originate from their particular caching behavior. As scrub jays spend their day foraging for seeds and acorns, they store their stash in little piles all over their territory in order to store up for when food is scarce. Rather than cooperating to build up one big pile, like the granaries of acorn woodpeckers, individual jays hide their bounty in many smaller piles. This strategy is called “scatter-hoarding” and leads to jays amassing counts of up to 200 caches within their home ranges, which average about 1/10 of a square mile.  Scrub jays must have excellent spatial memories just to remember where they stuck all these future snacks. This quickly becomes an impressive task; can you remember the last 200 places you ate out?!  Since the hippocampus is the part of the brain that is involved in memory formation and storage, researchers have wondered if scrub jays have particularly large hippocampi, given all this remembering that they must do. Turns out that, within the corvid family, scrub jays do have one of the largest hippocampus sizes compared to their body size (Pravosudov and deKort, 2006), providing hard evidence that having a bird brain isn’t necessarily a bad thing!

Hippocampus-Bird_brain (1)
A figure showing the hippocampus in a bird brain. On the left is the whole bird brain with the hippocampus in red, on the right are coronal slices through a bird brain showing the hippocampus in red.  [Source]
So, scrub jays must remember where they hide all their goodies for later snacking. This might be equivalent to you being able to remember all the locations of the last 200 or so restaurants that you ate out at. But let’s imagine that not only did you eat out 200 times, but you took leftovers home from each of those visits and all of them are still sitting in your fridge, unlabeled. Can you now remember what you ordered at each of those 200 restaurants, and when you went, to determine if those leftovers are still good? This “when” and “what” aspect is called episodic memory, which gives context to the past experiences that we remember. Dr. Nicola Clayton, a former UC Davis researcher, now at Cambridge University, was inspired by the scrub jays and wondered if they too had episodic memory.  To test this, Clayton and her team brought scrub jays into captivity and allowed them to cache peanuts (a long-lasting food) or mealworms (a perishable food) into little ice cube trays. The jays were then kept from recovering their snacks until after a certain amount of time had passed. Some scrub jays were allowed to return in a short period, while others had to wait a longer time. After the longer intervals, the jays returned to caches of peanuts first and faster than caches of worms compared to those jays held back for shorter time periods. This implies that the jays “understood” that the worms would have gone bad in the time they’d been gone, and weren’t worth revisiting first. Clayton and colleagues used this and further experimental evidence to argue for episodic memory in these birds (Clayton and Dickinson 1998).

scrub_jay_cache
A captive scrub jay caching food in an ice cube tray filled with sand. This was the experimental set up used in Clayton’s study investigating episodic memory in scrub jays. [Source]
Besides their prodigious memories, scrub jays also have a social awareness that they sometimes harness for more deceptive purposes. Despite their ability to cache and build up their own array of stockpiles, some scrub jays will watch where others cache and proceed to pilfer these piles when the original cache-makers aren’t looking. To protect themselves from this unwarranted thievery, scrub jays will cache in a secretive manner, hiding behind objects, or relying on shade to obscure them from other birds’ view.  Sometimes, though, these efforts are not enough. If jays “believe” another bird is watching them cache, they will return to the cache later and “re-cache” it to a new secret location so that their food cannot be stolen. This paranoia can be time- and energy-consuming, and isn’t commonly seen in the animal kingdom, because it requires a social skill called theory of mind. Theory of mind involves the ability to understand that other individuals know, or believe, different things than you might, and that they may have different information than you have.  The jays must “understand” in some way that the other birds are not only able to see what they are doing, but could also use that information to steal their hard-earned seeds.

scrub_jay_seeds2
Scrub jay collecting seeds, hopefully without anyone watching! [Source]
Interestingly, experimental work by Dr. Clayton and colleagues found that some birds act particularly paranoid, especially if they are guilty of stealing themselves. Birds that have pilfered other seed piles are more likely to go back and “re-cache” their own piles than birds that have minded their own business. Importantly, though, these scrub jays will only go back and re-cache if they are aware that another bird is watching them (Dally et al 2006). They won’t exert the energy when they are certain they are alone. While this may seem obvious enough to us as humans, it might come as a surprise that psychology studies show that it is only at age 4 that children start to recognize that others may not have the same information that they do, and thus can be tricked (Ashington and Edward, 2010). This implies that the lowly scrub jay may be more advanced in this regard than human toddlers!

With all this in mind (pun intended), I hope I’ve convinced you once and for all to retire that age-old bird-brained trope, and appreciate bird intelligence for all that it has to offer. And, if you were already convinced, I hope maybe you’ll have more appreciation for the intelligent being looking back at you the next time a scrub jay jolts you awake with its gut-wrenching screech.

For further reading: 

Hu, C. (2010) Who you callin’ “Bird-brain”? Discover Magazine.  Features work by Nicola Clayton while she was at Davis.

Ackerman, J. (2017) The Genius of Birds. Penguin Books.  Features the scrub jay and other intelligent birds.

scrub_jay_handsome
A handsome scrub jay sitting on a fence.  [Source]

References:

Astington JW, Edward MJ. (2010). The Development of Theory of Mind in Early Childhood.  In: Tremblay RE, Boivin M, Peters RDeV, eds. Zelazo PD, topic ed. Encyclopedia on Early Childhood Development [online]. http://www.child-encyclopedia.com/social-cognition/according-experts/development-theory-mind-early-childhood.

Clayton, N. S., Emery, N. J., Dickinson, A. (2006). “The rationality of animal memory: Complex caching strategies of western scrub jays”. In Hurley, Susan & Nudds, Matthew. Rational Animals? (PDF). Oxford University Press. pp. 197–216. ISBN 0198528264.

Clayton, N.S., Dickinson, A. (1998) Episodic-like memory during  cache recovery by scrub jays. Nature, (395): 272-274.

Dally, J.M.,  Emery, N. J. , Clayton, N.S. (2006). Food-caching western scrub jays keep track of who was watching them. Science, 312(5780): 1662-1665.

Pravosudov, V.V. ,  de Kort, S.R. (2006) Is the western scrub-jay (Aphelocoma californica) really an underdog among food-caching corvids when it comes to hippocampal volume and food caching propensity?  Brain Behavior and Evolution, 67(1): 1-9.

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