Drones to data

I’ve posted a lot of really pretty drone pictures and video these last six months and I’m realizing that this drone is actually pretty exciting tool for science communication. A reporter the other day said that she’d watched my Redonda video as part of her background research and it really helped her get a feel for the island. The original intent for the drone though was to capture high-resolution aerial photos of study sites to try to capture data on important but hard to measure ecological characteristics like vegetation cover, habitat availability, and maybe even habitat structure.

It’s a rainy Saturday in Boston so I decided to go back and look at some pictures from sunny Greece and see if I could start working with the drone footage to get some data.

The first step is actually capturing the video, of course, and that happened in Greece. I flew at a constant height (40m) in a straight line along the long axis of the island with the drone camera pointing 90 degrees straight down.

Here’s what that video looks like (don’t forget to click HD):

Now, that’s really pretty but for analyses I want a single, static image of the whole island. One option would be to just fly really high so the entire island is in the field of view. Unfortunately, since this island is so long, that’d have put me way higher than I wanted (or was allowed) to fly. This would also cause the resolution to suffer – I want to be able to see individual plants pretty clearly. The other option is to decompose that video, frame by frame, into a series of still images that I can then stitch together into a panorama.

This is actually pretty straight forward in in photoshop:

File > Import > Video Frames to Layers…

In this dialog box you select the video you want to make into still images and how many frames you want to skip per layer (the default is one layer every 2 frames). I chose one layer per 30 frames or approximately 1 image per second of video. That’ll give me good overlap to stitch the panorama together but not so many images that my poor computer will have to jigsaw hundreds of pictures together. You can then save those layers as independent images.

The final step then is just stitching together the panorama! Again in photoshop:

File > Automate > Photomerge…

Default settings worked great for me and voila, a beautiful high-resolution aerial photograph of an island in Greece.

Agios Artemios

Click on the image for a high-res look at Agios Artemios

So what about the data? I used my Oru Kayak seat as a launching pad on each of these islands. You can see it as the bright orange oval in the bottom third of the island. That orange launch pad is 80 cm across. With that I can set a scale that’s consistent for the whole island. I also know that the kayak is 360 cm long, which means I can check my calibration to make sure I’m getting good estimates. After that, it’s time to measure. I’m running out of time today so I haven’t made measurements but I’ll be calculating the  area of the island, the area of the green space, maybe even some metrics of patchiness, stay tuned!

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Kanena provlema

“Kanena provlema.” That’s what our taxi driver kept saying. Ultimately we made it, but getting the our kayaks, bags, and research equipment from the castle to the port on Naxos, and ultimately Paros was anything but “No problems.”

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First, as you can see, the kayaks fit in his taxi only in the most generous of senses. We got them in, and what’s more, they stayed, but only just barely. Luckily he showed admirable restraint on the bumpy, usually speedy, roads between the Castle and the Blue Star Ferry terminal.

As you might have been able to guess, Menelia (a PhD student at the University of Antwerp, and a partner in previous expeditions) and I had 2 kayaks, our personal stuff for a week or more on Paros, and three different bags/containers with research supplies in them. Last year we had Anthony along to help with the juggling, however this year we were meeting Anthony on Paros so it was up to us to get it all on and off the boat. What’s more, we opted to take the high-speed ferry between Naxos and Paros which seemingly doesn’t even stop at the dock, just idles its engines long enough to get people on the ramp before it departs again. Poor Menelia, our plan was to do the loading in shifts – I took the kayaks and a few bags aboard and went out to help with the massive tupperware of heavy research supplies only to find that she’d been yelled at by the port authority in the 2 minutes I’d been gone to get on the boat or get left behind. She started hurriedly pushing the tupperware chest most of the way up the boat ramp while loaded down with 3 bags herself. We never did find the water bottles we’d bought for the trip, they got cast aside in the hubbub I think. She was the last on the boat and by the time I got back to her, maybe only 3 minutes later, they were already lifting the ramp to depart.

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We managed our exit a little more carefully after the hectic and exhausting loading. Here we are, all smiles; though my smile is really a grimace — the double-crossed kayaks were cutting off airflow something fierce every time they shifted forward. The unloading was quite a bit easier though, at least we knew we’d be rushed and so were in the starting blocks ready to go. We shuffle-sprinted down the ramp and dropped all of our supplies just on the jetty, careful to avoid the cars rushing past to get their spot on the ferry before it left.

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And here we are, a view of the pile and the ferry just before it left. The pile doesn’t look that impressive but match the bags with the previous pictures for scale. With luck the rest of the trip should be a lot easier! (yeah, right…)

Old Maps

Sorry for the delay in posts. I was working through the data from the island manipulation experiment to share with you, but analysis started getting complicated and then I got busy getting engaged. Hurrah! I’m in the last field research push though so I’m going to try to post several updates over the next two weeks while I’m still in Greece.

The first fun story: I’ve found a very old map of the bay of Naoussa where five of my experimental islets are located. I want to share it with you.

There’s a section of Athens around the Acropolis called Plaka, and in one corner of Plaka, a small cluster of very old book stores. One in particular – I don’t know its name and can only find it once I’m lost and have nearly given up trying – has dusty drawers filled with old maps. The shopkeep is just the kind of barely sociable gentleman you’d expect with squinty, shadow-strained eyes and a suspicious air like he hasn’t quite made up his mind whether or not he’ll suffer to sell his wares to tourists.

I asked him about maps of Paros and he was at first somewhat reticent. Once I started rattling off names of bays and islets I think I convinced him I was worthy of seeing “the good stuff” and all of a sudden out came this tome from the 18th century:

Cover

If my Roman numerals are correct, it was published in 1782 and contains beautiful maps and illustrations of Greece. The book has numerous plates of landscapes and culture (alas, I wasn’t allowed to take pictures of those) and one beautifully detailed map of the bay of Naoussa in the north of Paros.

Big Map

The map was made in 1776 (date in the lower left corner) and is beautifully detailed with depth measurements, labeled islets, and interestingly, a count of the arrayed armaments throughout the bay. Naoussa at the time was a well-fortified stronghold (though I’m going to have to do some more reading to find out who, at the time time, was using it to defend from whom). Here’s a detail of some of the canon counts:

Galiatsos Naoussa The map is beautifully detailed:

Detail Key

Interestingly, the scale of the map is in toises. A little reading suggests that this length is around 6 feet.

Scale

All five of my islands are accounted for, however there are some interesting differences. In this detail for example:

GaliatsosThe large island without any detail (or canons) is Mavronissi, which is now two islands in close proximity separated by a narrow channel. I’m not sure if F. Kauffer just decided to omit that detail or if the island really has changed that much in the last 250 years. The small island directly north of that with a plus sign no longer exists. Sea levels have risen in the last 250 years but I’m going to have to do some more investigating to sort out what’s going on there. Finally, the large island directly east of Mavronissi is now solidly connected to Paros. All traces of these canons are long since gone from the islands, but it was fascinating getting this glimpse into the history of this area. Unfortunately I couldn’t afford the original map, but I did convince my new map-selling friend to give me a high-res scan, so I’ll be pouring over the details for quite a while to come.

The islands revisited

After several “are you still alive?” emails yesterday I think it’s time to update the blog! I’m sorry for the delay, but it was for good reason: this last week has been non-stop revisiting of the five introduction islands from last year.

I’m going to stretch this out over several posts because it was a lot of work and the results are really exciting. The short of it though: we found our lizards! All five island populations had survivors and they seem to be doing well. Some island populations had spread out over much of the island, others remained right in the neighborhood of their introduction site. All of the populations had new recruits – i.e. lizards that were born last year after the introduction, and just about all of the females we found this year were pregnant! That means they’ve figured out how to survive on the islands and now we can start tracking them year to year.

Each island required either ferrying people to and fro in kayaks or hopping on and off of Captain Rofo’s excellent boat. After that, the team stomped in line over the whole island noosing, baiting, or diving on anything that wriggled (to the surprise of not a few errant geckos).

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This photo was shot by SNRE MS student, Zachary Gizicki from the next island over where he was surveying vegetation for his thesis.

Once we caught the lizards, it was back to measure them, and put in a permanent PIT tag (more on that very soon!). These islands don’t exactly have a lot of cover though so we’d huddle in whatever shade we could find. Here’s a video of the team in a cave on Agios Artemios:

Thank you all of your support and excitement. I cannot wait to tell you more about the experiment, the process, and the preliminary results!

Still waiting on Aeolus

At my last post I was on Paros waiting for the winds to die down so we could get out to survey the experimental islets. Well, they never calmed. While I think we could make the kayak across the straits in one piece, the lizards are wisely hunkered down and we really can’t expect to get a decent count. So, instead of twirling our thumbs on Paros questioning the whims of Aeolus, it was back to Naxos to fill in some gaps in my lizard data from last year.

First though we had to try out the kayaks. It’d been a year and I couldn’t wait to get them set up again.

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Here we are on our way to Paros… undaunted as of yet by the wind.

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Just a pretty kayak shot against a beautiful cycladic door.

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All set up and ready to get their first taste of Mediterranean this year!

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Kayaking around the ramp and into the wind.

The first effort on Naxos was to survey herpetofauna in the lush northern valleys of the island. I should have taken some more landscape pictures – I was too busy flipping rocks – but we hiked a beautiful stretch of flowing stream with tall trees and diverse understory flora.

photo 3Here’s a beautifully built old stone house. I’m not sure if it belonged to a miller or to a shepherd but it’s withstood countless decades and will no doubt last decades yet.

photo 1One particularly exciting find near that stone house: this frog! Amphibians are hard to come by on the Greek islands. Most of the isles don’t have enough consistent water to support an amphibious lifestyle. This fellow’s name is Pelophylax kurtmuelleri. We were very excited to catch it!

After that survey it’s been 100% Podarcis. We’re stomach flushing again to get some more information on the diet of the lizards. We’ve already caught over 60 individuals and we’ve our eye out for a few more soon!

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Finally, here’s a pretty erhardii from the field.

The initial island survey

So I ended my last post in the description of the set up for the island introduction experiment at picking the islands based on google earth images. That obviously wasn’t enough, the next step was to get out there on the ground, assess the flora and fauna (most importantly to make sure that there weren’t already Podarcis), and get a feel for whether the island could support a population of these lizards. All of that legwork happened in May over the course of a few visits.

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Here are three islands we visited right out side of Aliki. The two largest turned out out to be too big for our purposes, but that third one in the center to the right is Tigani – one of my control islets without any lizards. That’s also where I found the Natrix!

Petalida

We did a lot of tramping about on islands (this is Petalida) looking for animals. In early May all of the flowers were blooming – all the islands look great. Things are much dryer now as you can see from the introduction video.

Trap

We were also anxious to measure baseline insect populations. To do so we arrayed a series of pitfall traps to catch crawling insects and sticky traps to catch flyers. We had to make sure there was food for the little lizards on these islands! This trap was on Agia Kali in the bay of Naoussa if you’re following along on the map.

Naoussa

For some of these initial trips where having lots of people was advantageous, we were reliant on local boatmen. Here’s a fellow named Bipis – an old sea hand rowing in to Galiatsos to tell us to hurry up. He didn’t love us – we were a bit slow for his liking. Glad we have the kayaks, we’ll be able to get to the islands on our own steam in the future.

Turlos

Captain Rufos based out of Aliki on the other hand was absolutely terrific to work with. Rufos is his nickname – it means grouper. He’s young and fun and seemed at the least better at faking interest in our research. It’s a good thing too because some of the islets between Paros and Antiparos he takes us to are a bit out of easy kayaking range. He’ll be fun to work with more in the future!

Glasses

And finally, a fun picture of the team reflected in Kat’s sunglasses.

So how’d you pick the islands?

So I gave you the end of the story first with that last post. Now that we have the local permissions and federal permits in hand, and the experiment started, I want to tell you a bit about what all went into deciding just how to set up this experiment. It was a long process! This’ll take a couple of entries, so stay tuned.

About 12 months ago, after National Geographic’s Waitt Foundation gave me enough money to start pursuing this project wholeheartedly, I began counting up potential islets in and around the large islands of Naxos, Paros, and Antiparos. My first criteria at that stage were size and accessibility. While there are plenty of rocks along these coasts, I needed an island large enough to support a lizard population. Many too of these islets are so steep that accessing them is dangerous. I eliminated all of these from the ‘potentials’ category.

The next criteria had more to do with island condition vis-a-vis humans. I definitely wanted islands that were uninhabited, and I was looking for islands that didn’t have a lot of grazing on them. Grazing of course is somewhat difficult to measure on Google Earth, but any uninhabited islands over about 50 m in diameter with some greenery made it through this filter, leaving me with about 16 good options to consider.

There’s only so much you can see from Google Earth, but it was an invaluable tool for narrowing the search so that when I got here I could go right to those islands, survey them, and make a final decision. Those surveys are the subject for the next post, but since I’m making a habit of giving away the end before talking through all of the beginning, here are the 10 islands we’re using for the experiment:

Naoussa

These first five islets are located in the bay of Naoussa on the north side of Paros.

Antiparos

 

These last five islets are further south in the straits between Paros and Antiparos. See if you can find them in Google Maps, and get a closer look!

(Next time I make a mapping post I’ll try to get my brother in on it! You should go check out his maps!)

*​This work approved in permit number 111665/1669 from the Greek Ministry of the Environment.