Tag Archives: cache

Crows and Shiny Objects

I got this question from csmithstudio on Tumblr:

Hi Jenn! A friend told me about your blog and I’m delighted and grateful to you for taking the time to post this! I am an artist focusing almost entirely on birds and I would like to do a painting of crows including the treasures they commonly collect. I’ve tried to research what they might be attracted to but so far have only found golf balls and angry golfers! Do they stash their hoard in a nest or somewhere else? Thank you! Christina

I’m super glad you asked me this!  I’ve been meaning to post about this topic.  The reason you can’t find anything is because crows don’t collect shiny things.  This is an extremely common myth, but it’s just that, a myth.  (And I’ve seen way too many “official” websites state this myth like it’s fact, so don’t feel bad for believing it!)  The thing is, stories about crows collecting shiny things are anecdotal, and not observed by people who watch crows constantly and study them.

There’s a couple of reasons why people might think crows like and collect shiny objects and continue to pass along the myth.  First, young crows are very curious about everything.  They play with all sorts of objects they find in nature, and chances are if something is glinting they may me more likely to explore that object (just like how you might notice something glinting in the grass and investigate it), than something that blends in to the background.  As I talked about in a previous post, juvenile crows are the same size and, to the untrained eye, look just like adult crows, therefore people may be attributing a juvenile play behavior to all age groups, accidentally.  Are they particularly attracted to shiny objects, or obsessed with them?  Highly unlikely, they may just be more likely to find them because they are easier to see/attract attention easier (welcome to why advertisers use shiny and bright things on other humans to attract their attention).  Honestly, adult crows are more likely to be terrified of brightly colored or shiny objects unless heavily associated with food on multiple occasions.

Second, a lot of observations about crows playing with shiny objects come from people who have had pet crows.  A hand-raised crow is going to have a lot of exposure to human objects, and will therefore play with those objects.  They may be attracted to what their “parents” (the humans) are attracted to, and therefore be more interested in rings, watches, silverware, etc. for the reason that they are of high value to their “family” not because they are shiny objects.

Third, it is likely that the shiny or bright objects simply remind the crows of food, or the crows are investigating them for potential food opportunities.  The going theory for why crows and ravens are so attracted to golf balls, as Christina mentioned in her note, is that they look an awful lot like delicious eggs.  I have personally watched crows play with and steal golf balls off a golf course (which was hilarious).  However, they lose interest pretty fast after, presumably, realizing the objects aren’t food (though I swear some of the crows just had a blast chasing those golf balls around).

There are a number of reasons why crows may be attracted to shiny or bright objects and trinkets, but no more so than you or I or most animals would be attracted to them.  In other words, their interest in shiny objects does not appear to be inordinate.

So, do crows hoard the objects they find?  No.

Crows don’t hoard anything.  If a crow takes off with your keys, it was likely that the bird wasn’t done exploring them for any food opportunities and took off with them to finish it’s inquiry in safety (and probably dropped them somewhere when it realized it had no use for the keys).  Crows, and other corvids, do cache items, which means that they store them for later (see my post about Nutcrackers for the most incredible cachers), but wild crows only store food items (I say “wild” because captive birds may cache non-food items, which would be expressing an instinctual behavior, using non-typical items found in the captive habitat).  Furthermore, they don’t cache all of the food items in the same location (larder).  Crows (and most corvids) are scatter cachers and leave bits of food all over the place within their territory (I once watched a crow pull half a ham sandwich out of the branches of a spruce tree…I still have NO idea where he was keeping it in there, but it was pretty hilarious to watch).  So there is no secret hoard full of shiny objects to find in a crow territory.

What about the nests?  Well, crows don’t use nests for anything but raising babies.  The nests are built just before egg-laying at the beginning of the breeding season, are lined with soft grass and moss, and are immediately abandoned once all the kids fledge.  Crows don’t store objects in a nest or sleep in a nest (unless you are a baby or the bird on incubation duty during the breeding season).  Although crows have been reported to use wire hangers and other urban metal materials to build the structure of their nests, this is more likely due to the utility and availability of these objects as construction material, not because they are shiny.  You may wonder if crows might put shiny objects in the nest to attract attention from potential mates, but crows have selected mates far before nest building begins.  If you find a crow nest in the wild, you won’t find wondrous treasures, you are likely to find a pile of sticks, grass, and poop….and sometimes a sleeping raccoon (true story).

So in conclusion, Christina, I would love to see you possibly illustrate caching behaviors of food, since those are the most valued treasures for crows.  In urban/suburban environments I’ve seen them cache everything from seeds and dead animals/insects, to ham sandwiches, pizza, and french fries.  It might be more fun (and accurate) for you to explore the wide and variable diets of these birds.  Feel free to contact me for more details if you are interested! 🙂

You have also given me the chance to review a game a friend bought for me recently, Crows by Valley Games, Inc.  I brought this game to a lab meeting and as a crow research group we played.  While thoroughly not impressed by the premise of attracting crows with shiny objects and trinkets, it was still quite fun!  We highly recommend it with the caveat that you replace “shiny objects and trinkets” with “peanuts and road kill.”  They certainly hit the mark with the trash tiles though.

A board game that is fun, but propagates the inaccurate myth that crows are inordinately attracted to and collect shiny objects.

 

Meet the Nucifraga

The genus Nucifraga includes some corvids that don’t get much attention by the general public, but that are highly, highly important to vast numbers of ecosystems.

The Nucifraga are commonly known as the nutcrackers.  Nucifraga literally means “nut shatterer” in Latin (nux, nucis = nut; frangere = to shatter) and as their name indicates, they specialize in eating nuts, specifically nutritious, high-fat nuts from pine cones.  Nuts aren’t the only thing they eat, but nuts are certainly the bulk of their diets along with invertebrates, small birds, eggs, and a bit of carrion.  The relationship of the nutcracker to the nuts they eat is one of the most fascinating biological mutualisms (a relationship beneficial to both species involved) seen in nature.  In some cases, the trees whose seeds the nutcrackers feed on rely upon the birds to disperse their seeds and plant them.  The planting of these tree species (such as whitebark pines and Asian stone pines) in otherwise cleared areas creates the foundation for colonization of other plant species and the creation of forests.  The story is far more complicated and interesting than what I just typed, but I think corvids and how they effect forest ecology will be relegated to a post of its own.  In the meantime, the Coyot.es Network’s own Chris Clarke wrote an article about the peril of whitebark pines and their corvid partners, “An Ancient Partnership Put in Danger“.

Another amazing attribute of nutcrackers is their memory.  Nutcrackers stay in their home ranges throughout the year, which tend to get a lot of snowfall and reach low temperatures with very little food.  To overcome this they cache (hide and place objects in the ground and crevices) seeds and recover them in the winter in order to make it through the winter.  (This caching behavior is how they plant the trees, mentioned above.)  In order to have enough seeds to survive in the winter they cache tens of thousands of seeds during the summer.  Remarkably, they recover 70-90% of those seeds in the winter.  Just think about that for a minute.  Some nutcrackers cache up to 30,000 seeds and they remember the locations of the caches, which contain 1-3 seeds, so that’s about 15,000 locations.  These caches are made during the summer, so in the winter the snow obscures and changes the landscape. This means the birds have to use various levels of landmarks and triangulation to remember the locations of the caches (sometimes this even requires the birds to completely burrow under the snow to get to the caches), along with toting an impressive long-term memory.  Okay, so they cache food in ~15,000 locations, which are obscured in the winter, and they recover food from ~11,250 locations despite the locations being obscured.  Let that sink in for a minute and think about last time you lost your keys or phone or wallet or anything.

What allows these birds to remember such an astounding amount of cache locations is an enlarged portion of the brain called the hippocampus, which is responsible for spatial memory.  However, their incredible memory comes at a cost.  There is only so much space in the skull for a brain, and only so much energy that can be devoted to brain matter, so other parts of the brain are reduced to compensate for the enlarged hippocampus.  Studies looking at the problem solving capabilities of nutcrackers makes them the dunces of the corvid classroom (to be fair, they are still pretty capable among birds in general).  These birds are memory specialists and they are certainly the champions of their specialty, but I point out their lack of problem solving capabilities because it has serious implications for how we define “smart” or “intelligent” animals.  Certainly in a memory task to “prove” intelligence the nutcrackers would defeat any challenger, but ask them to solve a novel problem and they flounder.  Does the inability to solve novel problems like other corvids make them any less cool?  No, it just makes them really interesting specialists in the family.

So who are the nutcrackers then?  There are three species, with multiple subspecies, all in the genus Nucifraga (as I mentioned above).  Let’s say hello!

Clark’s Nutcracker (Nucifraga columbiana)

Photo of a Clark’s Nutcracker (with bulging sublingual pouch) by Mike Ross, taken in Rocky Mountain National Park, Colorado.

This is the North American species of nutcracker found in the western half of North America from Colorado to the Pacific, from southern British Colombia and Alberta to southern New Mexico and Arizona.  Most studies involving memory and the mutualistic relationship between seed cachers and pine trees have been done with this species.

 

Spotted Nutcracker (Nucifraga caryocatactes)

Photo of a Spotted Nutcracker taken by Paul Cools in Veldhoven, North Brabant Province, Netherlands.

It cracks me up that the species name for these birds means the same thing as the genus name, just in Greek instead of Latin (from karuokataktes where karuon = nut; katagnumito = shatter).  Apparently they are so good at shattering nuts they got named for it twice!

This species has a huge range with 8 subspecies.  Generally the subspecies are divided into two group:, the Northern group, which ranges throughout Europe and Northern Asia to Japan, and the Southern group, which ranges throughout southern China and the Himalayas.

Subspecies of the Northern group, which tend to have more white spotting:

  1. N. c. caryocatactes (the nut shattering, nut shattering, nut shatterer)
  2. N. c. macrorhynchos
  3. N. c. japonica
  4. N. c. rothschildi

Subspecies of the Southern group, which tend to have less spotting/a more brown appearance:

  1. N. c. interdicta
  2. N. c. hemispila
  3. N. c. owstoni
  4. N. c. macella

 

Large-Spotted/Kashmir Nutcracker (Nucifraga multipunctata)

Photo of a Large-Spotted Nutcracker take by Menno Hornman taken in Chitral Gol National Park, Pakistan.

This species used to be a subspecies of Spotted Nutcracker, but has since been deemed its own species.  These birds have a relatively small distribution in the western Himalayan forests of northern India and Pakistan and presumably have similar habits of the other Spotted Nutcrackers, but are sufficiently genetically distinct to warrant being their own species.  They have a lot more, and larger, white spots, giving them a whiter appearance; both their common and species name point out this fact (multipunctata is Latin meaning multi =many and punctatus = spotted).  Ornithologists are extremely creative with naming, clearly.