Cache and Retrieve

Clark’s Nutcracker
Nucifraga columbiana

Courtesy Steven Pavlov
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license
 

Common Raven
Corvus corax

Courtesy US FWS
Gary M. Stolz, Photographer
 

Hi I’m Holly Strand.

Every year, just before Christmas, I comb through the house looking for presents hidden earlier in the year. I check inside old shoes, unfold towels in the closet, and peer way back into the dark recesses of seldomly-used cabinets. With a child in the house, you have to be tricky! The problem with this complex gift stashing behavior is that sometimes I forget where I hid the present when it’s time to wrap it! And once in awhile I forget that I bought something at all! Out of sight—out of mind!

You wouldn’t make a very good magpie, I have been told. For magpies– along with jays, crows and ravens, are masters at hiding–or caching as it’s called– and then retrieving. Of course, what they cache is not Christmas presents but food.

One Utah bird that is much admired for its caching and retrieving skills is Clark’s nutcracker . This large jay lives in mountainous areas throughout the west. Experts say that Clark’s nutcracker can cache 10s of thousands of pinyon, whitebark or limber pine seeds in a single season. Starting in August, the bird will hide 1-15 seeds at a time, often distributing them several kilometers and at much different elevations from the original tree. Caches lie 1-3 centimeters deep in forest litter, bare soil, under bark, in holes, in logs or stumps.

As winter wears on, the nutcracker will retrieve its caches with the help of visual landmarks such as rocks, trees or logs. Using these visual cues, the nutcracker will retrieve the seeds through summer of the following year. Forgotten or abandoned seed caches often germinate, growing into trees that produce more food.

Just as I worry about prying eyes when I hide Christmas presents, birds who cache must be careful to notice who is watching. The common raven is notorious for its spying and thieving behavior. One raven will covertly observe while another caches scraps of meat, eggs, bones or seeds. The observer will then shamelessly raid the cache usually within a couple of days. But having probably raided someone else at some point, the caching raven is on the lookout too. If the caching raven senses the presence of a would-be looter, it might wait for the other bird to become preoccupied. Or it may move the food to a different site altogether. Caching ravens will also hide behind some structure to avoid being seen.

Interestingly, these sly birds will even engage in fake caching. Ravens will cache inedible or low value food items in plain view of other ravens but then stash the good stuff in secret. Fake caching seems designed to throw looters off track, . But perhaps it’s also a character test for fellow ravens? Or maybe—for the intelligent raven—it’s all just an amusing shell game?

For sources and pictures for this and past stories, go to www.wildaboututah.org

For Wild About Utah, I’m Holly Strand.

Credits:

Images: Courtesy Wikimedia/ Steven Pavlov, Photographer
and Courtesy US FWS, Gary M. Stolz, Photographer
Text: Holly Strand

Sources & Additional Reading:

Balda, R.P. & Kamil, A.C. 1989. A comparative study of cache recovery by three corvid species. Animal Behaviour 37: 486-495.

Boarman, William I. and Bernd Heinrich. 1999. Common Raven (Corvus corax), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/476 .

Bugnyarf, Thomas and Kurt Kotrschal. 2001. Observational learning and the raiding of food caches in ravens,Corvus corax: is it ‘tactical’ deception? Animal Behavior, Volume 64, Issue 2, August 2002, Pages 185–195.

Heinrich, Bernd and John W. Pepper. 1998. Influence of competitors on caching behaviour in the common raven, Corvus corax . Animal Behaviour. Vol. 56, 1083–1090

Marzluff, John and Tony Angell. 2005. In the Company of Crows and Ravens. Yale University Press. http://yalepress.yale.edu/yupbooks/book.asp?isbn=0300100760

Tomback, Diana F. 1998. Clark’s Nutcracker (Nucifraga columbiana), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/331 .

Crow vs. Raven

Common Raven (Corvus corax)
Bryce Canyon National Park
Courtesy US National Park Service
And found on Wikipedia

American Crow Juvenile & Parent
(Corvus brachythynchosby)
Copyright © 2011 Wayne Whaley

American Crow, Orem, UT
(Corvus brachythynchosby)
Copyright © 2011 Wayne Whaley

American Crow Pair, Orem, UT
(Corvus brachythynchosby)
Copyright © 2011 Wayne Whaley

Hi I’m Holly Strand.

As you might have guessed, the American crow and the common raven are birds of a feather—two closely related species of the same genus Corvus. Both of them are residents of Utah. Together with family members magpies and jays, crows and ravens are among the brainiest animals on the planet.

Many times I’ve heard someone ask “Is that a crow or a raven?” or “What’s the difference between them?”

Perhaps the easiest way to tell these two apart is by size. If you are thinking to yourself “Wow! That’s a huge crow!” You are probably looking at a raven. Ravens can weigh over 2.5 pounds while crows typically weigh less than 1. The Raven’s wingspan can clear 4.5 feet while that of crows is less than 3. Proportional to their bodies, the bill on a Raven is larger and thicker.
The crow has a thinner, more pointed bill.

Take a look at the tail in flight: a crow tail is fan shaped with a straight tail edge. A raven tail has a rounded wedge shape.

In the air, ravens usually soar, while crows will flap a lot more. It’s not always apparent why, but some ravens will perform acrobatic rolls during flight—usually half rolls, but sometimes full rolls and even double rolls!

Common ravens are abundant throughout Utah, They can be found in almost all habitats and in all seasons. They are more wilderness-oriented than crows who prefer forest edges, savannas, agricultural fields and urbanized areas. In cities and towns humans provide lots of easy food in the form of garbage. The crows’ intelligence allows them to take advantage of novel food items– like pizza and Cheetos–that don’t really resemble food in the wild.

Finally, listen to the difference in sound: Here are two crows calling—an adult and a juvenile http://xeno-canto.org/recording.php?XC=72977 . Now listen to the throatier sound of the raven http://www.xeno-canto.org/america/recording.php?XC=12581
Crows will also scream, rattle, whine and coo, but most of the time they just caw. Ravens have a richer, more complex vocabulary. They’ll scream, trill, knock, croak, cackle, warble, yell, and kaw. Young birds reared in isolation have even been taught to say “Nevermore.”

Thanks to Ryan O’Donnell and Andrew Spencer for their recordings available on the web at www.xeno-canto.org

For Wild About Utah, I’m Holly Strand.

Credits:

Photos: Courtesy US National Parks Service &
Courtesy & Copyright © 2011 Wayne Whaley
Text: Holly Strand

Sources & Additional Reading:

Boarman, William I. and Bernd Heinrich. 1999. Common Raven (Corvus corax), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/476

Kilham, Lawrence. 1989. The American crow and the common raven. W. L. Moody Jr. Natural History Series. College Station: Texas A&M University Press.

Marzluff, John M. 2005. In the company of crows and ravens. Yale University Press.

Savage, Candace Sherk , 1997. Bird brains: the intelligence of crows, ravens, magpies, and jays. Sierra Club Books.

Verbeek, N. A. and C. Caffrey. 2002. American Crow (Corvus brachyrhynchos), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/647