Swarm Sunday – 2011 Year-End Report, Part 2

Dragonfly Swarm Project logo

It’s time for another year-end summary of dragonfly swarm data!  I just did my first formal presentation of this project, so I’ve decided to start incorporating the logos into anything related to the project.  For now on, if a post (or page or poster or brochure…) has the logo you see above, you’ll know it’s a part of the Dragonfly Swarm Project.  But let’s dive into the data.  Today’s topic: distribution of dragonfly swarms and the maps!

In many ways, this year was more satisfying to me data-wise than last year.  Part of that has to do with my compulsion to complete sets.  Last year, I was missing two continental US states and that really bothered me.  Why should Wyoming and Louisiana be left out?  This year, there was at least one report in each state of the lower 48!  I also received 174% of the reports I got last year, so it was a very good data collection year.

Mapping the year’s data turned out to be quite a big project, however.  Marking all 1130 sightings one by one took forever!  (Next year I need to figure out a way to map things more easily…)  However, some interesting patterns emerged from the data.  Like last year, I’m going to present the maps as videos to make the changes from week to week more obvious.  Please note: The pushpin colors delineate the two types of swarms, green for static swarms and white for migratory swarms, but each pushpin represents a unique report.  Also, the maps are quite small in the movies as you see them below.   I highly recommend viewing the maps in full screen mode (click the icon with four arrows in the bottom right corner) and then bumping the resolution up for the best viewing experience.

With that, I present the maps!  First up,  a series of maps showing the weekly change in the swarm locations.  The pushpins are cumulative such that each week’s are added to all the pins from the previous weeks:

Next is a map that splits the static and migratory swarm data for ease of viewing. Here, I’ve shown each month’s pushpins separately, starting with the static swarms and ending with the migratory swarms:

I hope the videos make everything reasonably clear!  There are so many ways you can present map data like this, but I wanted to keep things simple.  Watching the sightings accumulate each week gives you a good overall feel for the patterns in dragonfly swarms distributions in the US and Canada and I added the second video this year so that you can see when the swarming activity peaks more clearly.  I think the maps show several interesting things!

You’ll note right away that the majority of swarms reported this year (like last year) were static swarms.  Static swarms far outnumber migratory swarms, especially inland.  Static swarms also occurred throughout the season, though they were most heavily reported in the fall.  Migratory swarms were much less commonly reported and, though it’s difficult to see in the videos, were most heavily reported after the static swarming activity had mostly died down.

Last year, the center of activity was the midwestern US, the western Great Lakes states and Iowa.  This year, the center clearly shifted east a few states to the Ohio/Pennsylvania area.  However, there was some early activity in Colorado and along the Missouri and Mississippi Rivers.  I’ll discuss these patterns more in the next post.

It’s a little hard to see in the videos due to the way the pushpins are angled, but the most reports within 20 miles of both the east and west coasts were migratory, not static swarms.  The eastern migration was particularly heavy along the North and South Carolina coasts this year, though there was some activity further north as well.  The migration on the west coast occurred in the same location as last year, along the northern Oregon coast.  Interestingly, there were some differences when I compared the migratory swarming patterns between this year and last.  The 2010 migration followed three paths: along the east coast, the west coast, and the Wabash/Mississippi Rivers.  This year, there was very little migratory activity in the midwest.  I think there’s a reason for this, but I’ll explain it in the next post.  For now, just ponder the implications.

In 2010, there were many fewer swarms reported in the west than in the east.  It was hard to tell for sure from a single year’s worth of data, but it looks like swarms really are much more rare west of the Missouri River than in the east.  I’ll discuss the reasons why next week.  When I formally presented my project last week, one person asked if I thought the reason that there are so many swarms in the northeast is because there are so many people living in that part of the country.  I thought the question was interesting, but I don’t think the number of people in an area has much to do with the distribution of swarming activity.  It surely plays a small role, but I receive nearly as many reports from very rural areas as I do from urban population centers.  Also, if the distribution map depended solely on the human population in an area, then I would expect to receive many more swarm reports from the big western cities.  Notice the lack of pushpins in areas like Seattle, San Francisco/Oakland, Phoenix.  I think the maps show the true distribution of swarming activity in the US, and they’ll only get better as I add more data over the next few years.

Last year, I thought the 2010 swarming activity was something special.  I no longer think so.  Swarming activity was high again this year, so clearly 2010 wasn’t unusual.  I received many more reports this year than last too, which could indicate that this year was even better than last.  However, I don’t want to read too much into this.  While I definitely received more reports, the project also got a lot of national publicity this year.  I can’t separate out the impacts of this surge in the project’s visibility from the overall swarming activity for the year.  Based on all the data I’ve received to date, I now believe that swarming is quite a common event!  While any one person might not see more than a few swarms in his or her lifetime, the behavior is much more common than I expected!  And, thanks to the nearly 1800 participants of the Dragonfly Swarm Project so far, we are collectively learning something new and interesting about a behavior that would be impossible to study alone.  This project is an excellent example of how citizen science can help scientists like me tackle biological phenomena that would be otherwise incredibly difficult to research.  Go citizen science!

I’ll finish up here with a note.  I’m adding a page to the Dragonfly Swarm Project area of my blog that will house yearly maps.  If you’d like to compare the data from year to year, these maps are going to be the best way to do so.  The page will be up later today, so please feel free to browse the 6 maps that I’ve generated so far.

Check back next week for more 2011 Dragonfly Swarm Project results, the 2011 conclusions!


Have you seen a dragonfly swarm?

I am tracking swarms so I can learn more about this interesting behavior.  If you see one, I’d love to hear from you!  Please visit my Report a Dragonfly Swarm page to fill out the official report form.  It only takes a few minutes!



Want more information?

Visit my dragonfly swarm information page for my entire collection of posts about dragonfly swarms!


Unless otherwise stated, all text, images, and video are copyright © TheDragonflyWoman.com


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