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Denali field notes: A hare of another color

Up until the last few weeks, spotting snowshoe hares before they darted out from the adjacent vegetation was something I considered myself fairly lucky to do.  After all, it’s literally a matter of life and death for them to remain as undetected as possible.  As September came to a close, however, I found myself spotting them more often and from further away than I had previously, and not just from weeks of practice.  Their concealment was being betrayed by the very mechanisms designed to keep them safe.

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There aren’t a lot of animals that call Denali home all year long, but those that do need effective strategies for staying alive during the essentially 8 months long winter.  For Denali’s snowshoe hares, one of these strategies is to adapt in an entirely new winter outfit, something only 20 other animals in the northern hemisphere do.1 While in the summer they are a mottled reddish brown, starting around late September the hares grow in their nearly all white coats. The ears are typically the first to change, with the rest of the body following suit shortly thereafter.

 

This transformation is mediated by changes in the photoperiod that affect melanin production.  Although the full explanation is quite complex, the core mechanism is that the shorter day length increases the hormone melatonin, which suppress the melanin producing hormone prolactin.1

 

While this strategy is good one for long winters blanketed in snow, changes in snow regimes are making this transition more precarious.  Camouflage mismatch–which is generally considered when more than 60% of the coat is different from the surrounding environment–can result either from winter coats that have come in too early, before the snow arrives, or because the snow pack lingers inconsistently.  This year, the lower elevations of the park have yet to see so much as a flake of snow, though you wouldn’t know that by looking at the hares.  As I have already experienced, such mismatch makes hares considerably easier to detect, a big problem for basically everyone’s favorite winter meal.2

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Although hares can adjust the timing of their molts to a small extent, it won’t be enough to keep them in sync with the more dramatic shifts climate change has in store for the future.  This is especially problematic because hares don’t seem to be very aware of their mismatch and attempt to compensate behaviorally by say, hiding behind vegetation or choosing resting spots that more closely match their color.3 Other animals, particularly birds, seem better at this.  Rock ptarmigan for example will actually dirty themselves to more closely match patchy snow.4

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Given the immense selection pressure on these animals to match their environment and the high variation in the traits responsible for such color changes, it’s possible that hares will be able to keep pace with an already changing arctic landscape, but we don’t know for sure.  The alternative will be to add hares to the growing list of once common animals that now require invasive management strategies to stay afloat in the anthroproscene.

 

Literature cited

1. Zimova M, Hackländer K, Good JM, Melo-Ferreira J, Alves PC, Mills SL. (2018). Function and underlying mechanisms of seasonal colour moulting in mammals and birds: what keeps them changing in a warming world? Biol. Rev. 93: 1478 – 1498.1478 doi: 10.1111/brv.12405

2. Pedersen S, Odden M, Pedersen HC. (2017). Climate change induced molting mismatch? Mountain hare abundance reduced by duration of snow cover and predator abundance. Ecosphere 8: 01722

3. Zimova M, Mills SL, Lukacs PM, Mitchell MS. (2014). Snowshoe hares display limited phenotypic plasticity to mismatch in seasonal camouflage. Proc. R. Soc. B DOI:

4. Montgomerie R, Lyon B, Holder K. (2001) Dirty ptarmigan: behavioral modification of conspicuous male plumage, Behavioral Ecology 12: 429–438.

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Big changes you should know about

Dear followers,

First off, hello! It’s been a minute since you last heard from me, huh?  Well in that time there have been three major changes which warrant special announcements.  Most significantly is announcement #1: I finished my PhD!

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I wish I had been in a better place to discuss the process and even invite you to my defense, but it just didn’t go down that way.  It was a chaotic sprint to the finish that had me pulling my hair out up until the very last moment.  Why you ask?  Well because of announcement #2.  I was in an unusual time crunch to finish because I had a PostDoc waiting for me only a few days after the end of summer quarter (i.e my cutoff to graduate).  As we speak I am writing from my desk in Denali National Park where I am beginning my 1-year long  study on Canada jays!

Yes, I am mighty sad to say goodbye to the crows (though I’ll never really say goodbye), but I am so excited about working with this delightful species, particularly because of the broad conservation implications of this work.  You can read more about the specifics here and expect a dedicated post very soon.

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This bring us to announcement #3: the whole blog got an overhaul and a facebook page!  With a new title and research project under my belt, I thought it was only fair the blog got some new life too.  I reached out to a former crow field tech turned full time natural history illustrator Madison Mayfield to design a logo for the blog, and boy, did she do a flippin fantastic job.  I’ve also updated all of the pages and given the blog an official homepage.  Please poke around and see what’s new.

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I’ve been a bit reticent about creating a facebook page because I already do so much science communication between here, twitter and Instagram (both @corvidresearch) that I worry a facebook page may spread me too thin.  But I recognize that a good number of my followers here are not active on those other platforms, and I’d like to offer some of the scicomm work I do in those other places to those folks, including the ability to play #CrowOrNo.  In addition, I felt a real need for an official community space where you can more easily connect with one another to share photos, videos and stories.  Although comments on the Corvid Research facebook page are closed, I’ve created a connected Corivd Research group meant as a way for my followers to connect with each other (since you already have plenty of ways of connecting with me).  I will moderate the group insofar as membership requests and issues with trolling or abuse, but do not plan on being especially active there myself.  That is a space meant for you.  All that said, I want to be clear that the blog will always be the primary place I produce articles. If anything these changes mean things will be more busy here, not less! 

Phew, this has been a lot of updates!  Please check everything out and give me your feedback, particularly as far as the facebook stuff goes.  Maybe you don’t really want or need that space and if that’s the case I may get rid of it.  And shoot me your Canada jay questions so I can incorporate the answers into the upcoming post!

Best wishes,
Dr. Kaeli Swift 🙂

 

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Are you playing #CrowOrNo yet?

Crows, ravens, magpies, even blackbirds or other non-corvid species can be tricky to distinguish from one another if you’re a beginning or even experienced birder given the right angle or blurry photo.  While some of it is a matter of learning key field markers, a big part of effectively learning to distinguish these species is an eye for the subtle differences in portion or appearance that comes with practice.  I believe learning these skills is not only fun, but makes us more informed corvid lovers and birders.

To that aim, I’ve started a weekly #CrowOrNo “quiz” on my Instagram (@corvidresearch) and Twitter (@corvidresearch) accounts.  Every Wednesday at 11:30 AM PST, I’ll post one photo and it’s up to you to decide whether or not it’s really a crow.  At the end of the day I’ll share the answer and any tips or tricks that would have helped to discern the true species.  Play, share, or simply spectate.  Whatever you’re comfortable with is fine for me, as long as you’re enjoying the process and learning more about these wonderful animals!  Check out the photos below for examples from past weeks.  I hope to see you there!

Oh, and have photos you think would make good fodder for the game?  Send them my way!

Update: The game is also now available on the Corvid Research facebook page!

 

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