Monthly Archives: October 2015

5 corvid facts that will surprise you

With all the online crow trivia listicles that are already floating around it can be hard to come up with tidbits that are both factual and interesting.   I was up the the challenge though and am hoping I found at least one thing every reader didn’t know.  Let me know how I did in the comments section!

 1.   Avocados are toxic to crows.1

Well, really avocados are toxic to most birds, and many other kinds of domestic animals.  Avocados contain a molecule called persin, which the plant produces as a fungicide.  In birds, it can cause damage to the heart tissues, difficulty breathing, lethargy or even death.  The resplendent quetzal is a rare exception in that it can not only tolerate avocados, but is considered a crucial seed distributor of the plant.  So next time you’re considering sharing your Chipotle leftovers, make sure you didn’t order extra guac.

2.   Scavenging accounts for very little of a crow’s diet2

Scavenging, meaning the consumption of dead plant or animals material, is a crucial part of our ecosystem that is commonly the recipient of unfair prejudice. American crows often get thrown in with this lot, and while there wouldn’t be anything gross or insulting about this if it were true, it simply isn’t.  Whether you’re in the city or the wildlands, scavenging and active predation account for only a minority of a crow’s diet.  The bulk of their daily meal is made of human refuse, invertebrates and worms.  In the cities, about 85% of their diet is human refuse, whereas in exurban and wildland areas human refuse and invertebrates account for roughly equal proportions of their daily food (about 35% each).

Photo: W. Perry Conway/CORBIS

This scene is not as common as many people think! Photo: W. Perry Conway/CORBIS

3.  There’s only three places with no native corvids3

New Zealand, the southern part of South America and the poles (ok so I guess technically 4 if you want to be a stickler about it).  Why this is remains largely mysterious, but it probably has to do with where and how these birds radiated out from their ancestral origins.

Global corvid distribution. They'll be our avian overlords soon enough I'm sure.

Global corvid distribution. They’ll be our avian overlords soon enough I’m sure.

4.  They have some of the best spatial memory of any animal4

Every year Clark’s nutcrackers and pinyon jays store tens of thousands of seeds to sustain them through the lean winter months.  If they fail to retrieve enough they’ll perish, so a good spatial memory can literally be the difference between life and death.  To deal with this mental load, these two species (and other food caching birds) have a huge hippocampus relative to the rest of their brain.  With the spatial memory part of their brain super charged they’re able to retrieve 20,000-30,000 seeds with 90% accuracy or better.  I can’t usually retrieve my cell phone what that kind of accuracy so I certainly tip my hat to them!

Photo: Minnesota Birder

Clark’s nutcracker.  Photo: Minnesota Birder

5.  They account for the largest songbird in the world.5

The common raven is marginally the largest songbird of the world with a 4.9ft wing span and weighing in at up to 4.5lbs.   An extremely close second is the thick-billed raven, which is native Ethiopia and has limited range in some surrounding countries.  In fact, the two are so close in size that there are conflicting reports of which is bigger depending which publication you look at3,5.  Scientists finally resolved this dispute, however, and came to the consensus that the common raven is larger for the 2009 publication of the Handbook of the Birds of the World.*

Photo: Ignacio Yufera

Thick billed raven.  Photo: Ignacio Yufera

*This section has been updated from a pervious version which incorrectly stated that the thick-billed raven was larger.

Literature cited

  1.  http://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/avocado
  2. Marzluff, J.M., McGowen, K.J., Roarke, D. and Knight, R.L.  2001.  Causes and consequences of expanding American crow populations.  in Avian ecology and conservation in an urbanizing world (J.M. Marzluff, R. Bowmanm and R Donelly, eds).  Kluwer academic Press, norwell, Ma.
  3. Madge, S. and Burn, H. 1999.  Crows and jays.  Princeton, New Jersey: Princeton University Press 1999.
  4. Marzluff, J.M. and Angell, T.  2005.  In the company of crows and ravens.  Yale University Press.
  5. dos Anjos, L., Debus, S., Madge, S., & Marzluff, J. (2009). Family Corvidae (crows). In J. del Hoyo, A. Elliot, & D. A. Christie (Eds.), Handbook of the birds of the world (Vol. 14, pp. 494e641). Barcelona, Spain: Lynx Edicions.

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Filed under Corvid trivia, Just for fun

The science of crows and death

Curious to read my popular science take on our recent publication on how crows behave around their dead?  Check out my latest article for Biosphere.  Then check out all the other awesome authors and contributors to my favorite popular science publication.  You won’t regret it.  (And congrats to GO for making the article cover!  She’s such a gorgeous bird…)

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Filed under Crow behavior, Kaeli in the media, New Research, women in science

Crowtography

People underestimate how beautiful corvids are.  In my field experiments, I’m so often wrapped up in taking the data with as much efficiency and focus as possible, that it makes it hard to step back and really take a bird in.  So it’s in the quiet moments outside of my fieldwork that I make time to really see these animals.  To do nothing more than watch as the sun brings out those rich colors hiding among the black pigments and marvel at how spectacular they really are.  On some of these occasions I make an effort to bring my Nikon with me.  Here are some of my favorite photos from those outings which I hope you delight in as much as I do.  File_001DSC_1648  File_000 File_002  File_008 File_004 File_003File_006 File_007 File_009

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Science in Seattle

Biosphere

Looking at the hard copy of my recent publication, I can’t hep but marvel at how clean it looks and feels.  Each sentence is as crisp as the months long editorial process could make it and each section offers a critical addition to the simple narrative: Crows gather around their dead to learn about danger.  As any of us in field biology know, however, the austere, concise nature of our publications make every effort not to betray the dirty, messy, sometimes chaotic process that defines the research experience.

Equipment breaks, ideas don’t work, field sites get destroyed, animals refuse to cooperate, money runs out, these are all par for the course for any field biologist, and any “field” is going to come with its own hazards.  My field, of course, was the city of Seattle.  By now, most readers are familiar with the look of our experimental set-up; a masked person with a “UW research” sign holding a dead crow.  We could have made the sign the size of a billboard and it still couldn’t have eliminated the sense of shock those latex masks instilled in people.  So you can maybe imagine how conducting those experiments in the heart of downtown, in people’s parks and neighborhoods, went over.  But you don’t have to.

biosphere 2A few months ago an excellent new popular science publication, Biosphere Magazine, approached me about doing a story detailing my experience as an urban field biologist.  Today, with their permission, I’m posting the story in its entirety.   I hope it gives you some insight into the research process, but I also hope it encourages you to check out this delightful new publication.  I have no doubt it will feed your hunger for science.  Enjoy!

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