Staying on target

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Hello, Mark My Bird lovers!

Once again, you’ve blown us away with your enthusiasm. It’s been less than two weeks since we launched, and last time I looked, you guys had collectively marked over 2,500 bills. A notable mention at this point has to go to Peregrin3, who since registering two days ago, has marked around 400 beaks. Amazing!

A few of you have asked for feedback on how well you’re doing. This is important for us too, because it helps us to identify mistakes that could affect our analyses later. Reassuringly, most of you are doing just fine. There are a few common mistakes that crop up, which we’ll take a look at below. We’re working on some updates to the landmarking tool that should flash up a warning if your landmarks start to stray too far from the brief.

How does this work then?

As we’ve already hinted to some of you who follow us on Twitter, there are some quality control measures built in to the site. One of them is that everyone who registers is given the same two training birds as the first bills they landmark: the shoebill stork (Balaeniceps rex), and the brown-chested alethe (Alethe poliocephala).

This shoebill is coming to haunt your dreams and steal your soul... © Su Neko, CC-BY-2.0

This shoebill is coming to haunt your dreams and steal your soul… © Su Neko, CC-BY-2.0

We chose the shoebill because a) it’s “easy to landmark” (big, sharp lines, sensible feathers), and b) just look at it. Look at it! It’s brilliant. We chose the alethe because, in terms of beak shape, it’s incredibly average, making it typical of most of the bills a user will see on Mark My Bird. The repeated efforts to mark these birds are our dataset for this blog. We’ll focus on the shoebill first.

I’m not going to dive in to the details of how we ran this analysis today. The method is called Geometric Morphometrics, and I’ll probably write another blog for you on that at a later date. In a nutshell, we’ll be using it to see how much variation in bill shape there is between different bird species. In this case though, everyone marked the same shape (the same shoebill… bill), so the variation will be caused by different people choosing to put their landmarks in slightly different places. For those of you who are in to morphometrics, all the analysis was done in the Geomorph R package.

Science!

Here’s what all the shoebill data you guys generated looks like:

shoepc12_rings

Each dot on this graph represents a different person, 165 in total. 85% fall inside the green circle, and have put the landmarks very close to where the members of Team Macrobird did. So well done! The person who came closest to our landmarks was hughbrazier (black dots), whose landmarks are shown compared to mine (grey dots).

shoe_hb

hughbrazier’s shoebill landmarks

What about the points that aren’t in the green circle? There are two more clusters in the graph, shown by the blue circles. These represent “loops”, where the user tried to add more points along the curves in between points they’d already placed. The point resampling along the curve gets really confused, and makes a right mess of things! One cluster is loops along the left and right curves, the other cluster is loops along the midline.

This is what happens when a loop gets put along one of the edge curves. It doesn't look much like a shoebill any more.

This is what happens when a loop gets put along one of the edge curves. It doesn’t look much like a shoebill any more, tbh.

We didn’t see this coming, but with hindsight, this is kind of our own fault. We should have been more specific in the instructions that the points along the curves have to be clicked from front to back in order. We’re working on an automatic check to try and stop people from making this mistake in the future.

I won’t name and shame the worst shoebill. Not only was there looping, but as this person looped, they also managed to mix up their left and right. Whoops!

We had slightly less data for the alethe, as 33 people had had enough, and stopped marking after they’d done the shoebill. It’s pretty much the same story, although this time, JohnF was closest to our landmarks.

JohnF's brown-chested alethe landmarks

JohnF’s brown-chested alethe landmarks

You can see that there is a small difference between where JohnF decided the keratin met the feathers and where I did. These small differences are the sort of thing we’d expect to see on a typical bill on Mark My Bird, and is why every bill has to be marked by multiple people: we need to get an idea of how much “noise” there is in the data.

In conclusion

We have some work to do to the back end of Mark My Bird, but the good news here is that most people are doing a great job. You carry on being fantastic. And if you want to see your own shoebill or alethe, post to the forum or send us a tweet with your Mark My Bird username, and we’ll try to get back to you ASAP.