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The birds and the bees

~This post describes sex in explicit terms ~

It’s springtime in Seattle which means the air is marked with the scent of warm, wet earth, the cherry trees are in full bloom, and our conversations of the goings on in the natural world are couched in the phrase “the birds and the bees”.  While its origin story is not completely clear, it’s very likely that this euphemism has been around for hundreds of years, dating back as early as 1644 in the Evelyn Diaries.  Despite the phrases’ ubiquity for discussing human sexuality, ironically very few people know much about the sex lives of the phrase’s subjects.  This is attributable largely to the fact that how these animals procreate is quite different from the mammalian systems we are familiar with.  So in the spirit of springtime let’s talk about the birds and the bees, the real story of the birds and the bees.

Birds
The most consequential departure by birds from mammalian systems is that most birds lack any kind of external sex organ. In contrast, most other kinds of animals have sex organs that are either maintained outside the body permanently, or can emerge temporarily as needed. Among birds, there are exceptions to this but fair warning you’ll probably never look at a duck in the same lighthearted way again if you pursue this line of knowledge. Which is to say of course that you absolutely should.

As far as crows and other songbirds are concerned though, sex must be conducted without penetration by a sex organ. So instead, these birds copulate by way of the “cloacal kiss”.  The cloaca is a bird’s single external vent and it’s used for both waste elimination and reproductive activities. During the breeding season, both the male and female’s vents swell.  To copulate, the male mounts the female and pushes her tail aside with his.  Once they make cloacal contact, the sperm that’s been stored in his cloaca is transferred.  It’s an awkward looking balancing act that lasts only a few seconds.  After the initial copulatory event the pair may mate again several times within minutes or over the course of weeks.

Whereas people need to consider timing, birds can successfully mate even in the absence of ovulation.  That’s because females have specialized sperm storage tubes inside their oviducts.  A female’s vagina is very picky, however, and only a very small number of the male’s sperm will reach this holding chamber.  Depending on the species, once there a female can store the living sperm for weeks or months. The exact mechanism of how the sperm are subsequently released is not entirely known, but possibilities include that it’s the mechanical pressure of the passing ovum (unfertilized eggs) that releases the sperm, or that it’s directed by hormonal changes during ovulation.1

One additional consequence of sperm storage is that it allows for different eggs within the same clutch to be sired by unique males.  In crows for example, about 80% of a nest has been sired by the female’s permanent partner.  It is unclear how many of these extra pair copulations are either solicited by or forced on the female.

Bees
While mid-air copulations have never been confirmed in birds, honey bees do in fact mate on the wing during what’s called the mating flight.  A newly minted, week old queen will take to their air followed by thousands of male drones.  She will only mate with about 10-20 of these individuals though.  To mate, the male inserts his endophallus (bee penis) into the queen’s sting chamber.  Once he has deposited his sperm, the male detaches.  Unfortunately for the male, however, he doesn’t do so with all the parts he arrived with.  His endophallus will rip off and remain inside the female, most often killing him.  As if that wasn’t brutal enough, the next male is required to remove the previous suitor’s leftovers before being granted the ability to seal his own fate.

By the end of the mating flight, the queen will be carrying hundreds of millions of sperm, most of which will be used immediately to begin fertilizing her eggs.  Like birds, the queen has a specialized storage chamber called a spermathecal where she keeps the unused sperm.  The stored sperm from her mating flight will last up to 4 years, after which the queen’s reign will come to an end, and the cycle begins anew.

Literature cited

  1. SASANAMI, T., MATSUZAKI, M., MIZUSHIMA, S., & HIYAMA, G. (2013). Sperm Storage in the Female Reproductive Tract in Birds. The Journal of Reproduction and Development, 59(4), 334–338. http://doi.org/10.1262/jrd.2013-038

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NCI corvid class open for registration

Hi Folks!  A few posts ago I mentioned the North Cascade Institute’s corvid class taught every June by John Marzluff and myself.  Good news; registration is officially open!

For those of you that missed my previous post, the corvid class is an overnight course hosted in the beautiful North Cascades alongside those iconic glacial blue lakes. During the class we will venture into snowy mountain passes to search for grey jays and nutcrackers and then head down to the Methow valley in search of magpies.  It’s not unusual for us to see nearly every species of corvid found in Washington state by the end of the trip.  To finish each day you’ll be treated to short corvid lectures and the wonderful meals provide by the NCI cooks.  It’s a wonderful class, so if you have the means I encourage you to register.  There’s limited spots available, however, so do it quickly!

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“Mirror, mirror on the wall

am I the smartest of them all?”

…Is not a question crows are asking, despite what you may have heard.  Because they, like basically all the super smart birds, are really, really bad at the mirror test.

Jungle crow mirror

A juvenile jungle crow catches its reflection in a window. Photo: Paul Brown

This might contradict what you’ve heard elsewhere.  But the reality is that corvid after corvid fails the mirror test.  Except two European magpies.1  That’s right,  every sound bite you’ve ever heard that corvids possess self awareness (as evidenced by their excellence at the mirror test) is based on the performance of two birds. But more on that later.

In humans, self recognition in mirrors emerges reliably when we are about two years old and it marks the beginning of a developmental process that culminates in the rich consciousness that makes us human, at least abstractly.  Given a mirror’s significance to our own understanding of the self, it’s no surprise we’re so curious to see what non-humans animals do, and more curious still to see if it can show us whether they share our possession of consciousness.  In fact, putting animals in front of mirrors and looking for signs of recognition is something we’ve been doing, at least officially, since the 1970’s.   Since those initial studies on chimps, a debate has raged over the outcomes and overall efficacy of such tests.

A mirror test is generally composed of two parts.  The first is spontaneous self directed behaviors.  In other words, when an animal encounters a mirror for the first time, does it react like it’s looking at itself with behaviors like self exploration or does it freak out at this stranger suddenly standing in front of it?  What about after it has 100 hours of experience with a mirror or a 1,000?  The second test is known as the ‘mark test.’ A mark like a red or blue dot is applied to the animal without its knowledge and we watch and see if once it gets in front of the mirror it tries to remove or at least touch the mark.

With respect to both these tests, from African grey parrots to New Caledonian crows, we see consistent failure, or at best inconsistent maybe-kinda success.2,3 For the record, while there’s no published tests that have been done on American crows, I can tell you that I’ve watched reflective windows and car mirrors ruin many a breeding crow’s afternoon plans. In Mind of the Raven, Bernd Heinrich reports a mostly neophobic response among his captive birds, punctuated in some individuals with moderate curiosity.

So what of Gretie and Goldie, those two magpies that did show higher mark recognition when given a mirror than control birds?  There’s two problems. The first that they used stickers to mark the birds and it’s difficult to know whether it was really the mirror eliciting the behavior or if maybe they could just feel the stickers. This idea was championed after a study done on jackdaws found that birds without mirrors detected the stickers just as often as those with mirrors.4  If they had detected them equally zero times then it might just indicate that jackdaws are bad at the test, but the fact that they did detect them in both cases is what raises the alarm because it shows the birds were somehow sensing the stickers in the absence of the mirror.

The second problem is simply:  what can two birds, especially out of a sample size of five, really tell us about whether corvids understand their reflection in a mirror anyway?  Not much.

Maybe you’re thinking “well, perhaps they just don’t understand how mirrors work at all, so of course they don’t recognize themselves.”  This isn’t a bad idea but it doesn’t appear to be true.  In that study on New Caledonian crows for example, while the birds didn’t show any self recognition behaviors, they could use the mirror to find hidden food. This demonstrates that they can exploit the properties of a mirror, and understand that mirrors reflect objects in the real world.  We see the same in grey parrots.

So now that I’ve gone and dampened things, let’s just go ahead and soak the rest of that blanket.  Because even if corvids or other birds passed the mark test with flying colors, it wouldn’t necessarily mean they are self aware   which is kind of the point of the whole test.  Enter pigeons.  Since the 1980’s we’ve known that pigeons excel at the mark test with a little bit of training, just like they can excel at shape discrimination or any number of other seemingly complex tasks.5  But the ability to learn isn’t in and of itself a reflection of capacity for complex thinking.  After all, it only takes 8 days to train a spider to solve a maze.6

pigeons

Pigeons in the original Epstein et al. 1981 paper

So does failing the mirror test mean corvids don’t possess theory of mind or the capacity for self awareness?  No.  Based on other studies, particularly those in ravens, it may be more likely that a mirror test, at least in it’s most common form, is just not a biologically appropriate way to ask this question.7,8  So don’t write off the capacity of a corvid to know thyself just yet.  But maybe offer a polite “ah, hem” the next time someone marvels at the narcissism of magpies.

Literature cited

  1. Prior, H., Schwartz, A. and Güntürkün, O. (2008). Mirror-induced behavior in the magpie (Pica pica): Evidence of self-recognition.  PLOS Biology 6: https://doi.org/10.1371/journal.pbio.0060202
  2. Pepperberg, I. M., Garcia, S. E., Jackson, E. C., & Marconi, S. (1995). Mirror use by African Grey parrots (Psittacus erithacus). Journal of Comparative Psychology, 109: 182
  3. Medina, F.S., Taylor, A.H., Hunt, G.R., and Grey, R.D. (2011).  New Caledonian crows ‘ responses to mirrors.  Animal Behaviour 82: 981-993
  4. Soler, M., Perez-Contreras, T., and Peralta-Sanchez, J. (2014).  Mirror-mark test performance on jackdaws reveals potential methodological problems in the use of stickers in avian-mark test studies.  PLOS ONE 9: https://doi.org/10.1371/journal.pone.0086193
  5. Epstein, R., Lanza, R.P., and Skinner, B.F. (1981).  “Self-awareness” in the pigeon.  Science 212: 695-696
  6. Punzo, F. (2000). An experimental analysis of maze learning in the wolf spider, Trochosa parthenus (Areaneae: Lycosidae).  Florida Scientist 63: 155-159
  7. Clary, D. and Kelly M.D. (2016).  Graded mirror self recognition by Clark’s nutcrackers.  Scientific Reports 6: doi:10.1038/srep36459
  8. Bugnyar, T., Reber, S.A., and Buckner, C.  (2016) Ravens attribute visual access to unseen competitors.  Nature Communications 7.  doi:10.1038/ncomms10506

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I need your help or Corvid Research is toast

About three years into my graduate program the emails, letters and blog comments started. A trickle at first, maybe only one or two things every couple of months. Now, five years into my program, the questions, calls for help, requests for opinions, and desire to share stories of corvid joy, sadness or sheer mystery are relentless.

And I love it. It’s one of my favorite parts of my work. Few graduate students get to engage with the public in the way that I do or will ever experience the public appreciating the research they do or the expertise they’ve acquired through the often tremendous personal sacrifice of being a grad student. Hardly any will ever get an email saying “your research is so cool” or “keep up the good work” or “your work changed my heart and mine about something” or “thank you.” They won’t ever hear those words despite the fact their research may have far more reaching and positive effects on the health and wellness of their non-human and human communities than mine does. But I do get to hear those things because the nature of my research means it makes for a cool blog and gets written about in publications like National Geographic and The Week.  And I am truly grateful for that. But on behalf of all those students who aren’t so well known I want to use my platform to ask something of you now.  Because our existence as graduate students is under attack.

If you’ve been keeping up with current events you’ll know that our GOP leaders are working on a tax reform bill. What many people do not yet know, however, is that the current bill will do away with key features intended to help make higher education affordable. Including:

–Section 117(d), which exempts tuition waivers from being counted as taxable income

–Section 127, which exempts employer education assistance from being taxed

–The Lifetime Learning Tax Credit

–The Student Loan Interest Deduction

–Consolidation of the American Education Opportunity Credit to only be used for 4 + 1 years

I could write whole blog posts on every one of those points but for the sake of brevity let’s focus just on the first one, the tax exemption for tuition waivers.

Most grad students working in STEM fields (Science Technology Engineering and Math) fund their degree with teaching assistantships or research assistantships. In my case, I started with an RA because I had an NSF Fellowship and when that ended after three years, I transitioned to a quarter by quarter struggle to find a TA position. For my TA work, the university pays me at 50%, meaning I receive a salary based on 20 hours of work (despite the fact most TA’s work considerably more.) My annual stipend is $23,000, but it can vary anywhere from $15,000-35,000 depending on your source of funding and state. This money is intended to provide basic cost of living and for many students, especially those with dependents, it barely covers that. But we make due because there’s few other options, we love science, and we know that our work has a meaningful impact on our communities.

This stipend money, regardless of the source, is taxed. As it should be. But in addition to a small stipend these TA and RA positions include tuition waivers which are valued at anywhere from 12-50k a year. This waiver is basically the University paying itself for our tuition and under the current system it’s not considered income. The waiver is designed to offset the considerable costs of pursuing higher education in this country. And, because grad students aren’t just professionals in training, but are currently contributing to our universities (and communities at large) through our labor, research and publications, it seems reasonable that we shouldn’t be paying for work we do in their name.

Losing this tuition waiver would mean students like me would still be getting paid about $23,000 but taxed as if our salary was in the neighborhood of $60,000. In fact some grad students are poised to have the biggest tax hike of any demographic under this new plan. That’s not financially feasible for most people (including myself), especially those who have already accrued debt from their undergraduate education, or who come from low income families, or those supporting dependents. It would be a disaster for STEM. 

Let me be clear: I’m not trying to paint the plight of grad students as the most important casualty of this bill. There are lots of reason to oppose it and we can’t all be fighting the same battle when are are so many different ones underway. But if you are reading this because you know and appreciate my research, popular articles, #CrowOrNo, blog, or even if you just care about STEM…that it continues to exist and attracts people of all financial means, then I need you to call or write to your legislators. They need to know that their non-grad student, tax paying constituents want to keep people like me in school.  If you need any help navigating how to do this please use this resource: Action Alert! – Tax Reform.

I will be here to answer your crow questions from now until well after my run at grad school ends.  But this time I need you to return the favor.  Please contact your legislators.

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How crows responded to the eclipse, according to you

Back in August, I challenged my readers to submit their observations of how their local crows responded to the total (or partial depending on your location) eclipse that occurred on the 21st.  Six of you offered up your observations and suffice it to say they ran the gamut.  From completely typical behavior to massive gatherings deemed unusual, there was no pattern to the handful of observations that were reported.  Here’s my summary of what you observed:

Three people reported no changes in behavior, with one person even witnessing a crow flying overhead during the moment of totality.

Two people reported seeing more crows than usual and that they were more noisy.  Almost like a typical pre-roosting behavior but in the middle of the day.

One person reported that the birds were more quiet than usual, and remained quiet for 30min after the eclipse.

I myself failed to find any corvids during the totality but I did watch a sparrow (not identified to species) forage on the ground just before, and just after the totality.  I did not see where it was during the few moments of complete totality, though given its proximity to its position prior to totality I reasoned it must not have gone far and could have easily been foraging as before just without my detection.

Thanks for sharing your notes everyone!  Looking forward to the next round in seven years 🙂

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How will crows respond to the eclipse? 

Unless you’ve been living under a rock, you know that this coming Monday a total solar eclipse will cross the continental United States. Eclipses are significant moments in the lives of humans but scientists know less about how non-human animals respond to them. After all, opportunities to observe this phenomenon occur only a couple times a year, and its occurrence in the same geographical area is substantially more rare. The last total solar eclipse in the US was in 1979. Since then, not only has our technology to research this phenomenon evolved, but methods for the public to engage in eclipse related citizen science has exploaded. You can read about all the different opportunities here.


Of these opportunities, the one that excites me most is the California Academy of Science’s ‘Life Responds’. By using the iNaturalist app, CAS invites you to make and report observations of how a particular organism responds to the eclipse. The instruction are simple and you can read the full protocol here. I encourage all my readers to consider participating with any species you choose, BUT I thought it might be fun to host a mini crow-specific Life Responds challenge here on the blog. 

How will crows or other corvids respond to the eclipse?


To that end, I invite all of you to follow the Life Responds observation protocol, and in addition to sending your observations in via iNaturalist, email them to me or leave them in a comment here. I’ll then synthesize all your observations into a little mini report that we can all learn from and enjoy. Sound fun? I hope so! 

Remember, if you chose to participate, please follow the Life Responds protocol. While I’ll certainly accept general comments/observations, if everyone follows the same collection method our observations will be much easier to synthesize and interpret. 

Not able to be in the path of totality? No problem! Your observations are still invited and valuable. I’m particularly interested in whether or not Seattlites observe the crows abandon their daytime activities and head towards the roost as the light changes. I myself will be down in Oregon in the path of totality, so I’ll miss that observation. Hopefully I can locate a corvid from my observation spot in Oregon. If you have questions let me know, otherwise enjoy the eclipse and remember to protect your eyes 👀! 

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A story you might enjoy

Generally speaking, I don’t write posts advertising specific stories or news articles about my work.  I figure anything going in those stories is all stuff you can get firsthand here, and of course I link to all of them on my ‘In the Media’ page so they’re never far out of reach anyway.  But I wanted to put out a special post about Vicki Croke’s article for the WBUR’s The Wild Life blog.  Most of the time when people write about me, the blog is a footnote, a way to learn more if you wish, but not something mentioned specifically.  As a follower of this blog, I imagine you have some idea how much time and effort I put into it (as much a grad student’s life allows for it, anyway) so I was extremely flattered and honored when Vicki made the blog a focal point of the article.  Given the supportive community we have built here together, I thought you especially would enjoy reading this piece.  Let me know what you think of it in the comments and thank you for your continued presence here and passion for crows.

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