Animation!

Go to this site to watch a very cool animation of the tortoises moving across Pinta!

I just think it's so cool to see them moving in relation to one another - much better than just a bunch of points on a screen. I especially like watching Wilman move down to the Southeast and then Wacho following him. I remember when Ben and I observed the two of them together in the same beautiful cactus grove.

-Elizabeth, Syracuse

Update on Mario, Javier, and Freddy

Here's an update on the 3 tortoises that have satellite tags on them - Mario, Javier, and Freddy. This first image shows their total track since the introduction (the black point). Mario is in yellow, Javier in pink, Freddy in blue.



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Now here's just the segment of the track for where they've been going for the past couple of months (August 9 - October 4).



You can see that Freddy seems to have settled down up in the higher elevations, while Mario and Javier continue to wander. I suppose this could mean that most of the rest of the tortoises are still wandering, too. No way to know until I go back, though!

-Elizabeth, Syracuse

Hello world

My friend is starting a scientific blog of his own, and his questions about the "blogosphere" prompted me to actually look at all of the different options that blogger provides. I found this stats thing that will tell you where the ip addresses are that have been viewing the blog. Most of the views are from the US and Ecuador (makes sense), but there are also quite a few from such far-flung places as Austria, Russia, India, and Indonesia, just to name a few! This probably comes as no surprise to people who are fully committed to the digital age, but to me it is amazing that people on the other side of the planet have read about what we're doing on a tiny island in the Pacific. I have to admit, it's pretty cool. Thanks for reading everyone!

Reminiscing...

I have recently given a couple of talks here at ESF about our time spent on Pinta, and I will give another talk at the Rosamund Gifford Zoo in a couple of weeks. Usually I'm very nervous about talking in front of a large group of people - the qualities that make one enjoy spending time on an uninhabited island are not necessarily the qualities that make one good at public speaking. But when I'm talking about Pinta and the tortoises, after an initial moment of nervousness, I'm completely in my element. It's even fun! Of course, it helps that I have such an interesting and charismatic subject.

Anyway, I thought I'd (finally) post some pictures that bring back fond memories.


An inquisitive Galapagos Flycatcher...
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Wilman exploring the lava field as a concerned Ben looks on.
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Our favorite chick (and protective parent).
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Pancho y Pancha.
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Wildlife photography is easy in the Galapagos!
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Mmm...peaches.
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Garrison was such a dedicated cactus pad counter.
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Don't miss those male seal lions too much...
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I miss the tortoises the most (this is Pedro).

Some preliminary results

Here are some preliminary results that I wrote up for a grant proposal that James and I submitted to the Galapagos Conservancy. We hope to go back to Pinta next summer to check on the tortoises and the changes in the plant community. With Matt Buff, web guru, we made a cool animation of the tortoises moving over the landscape - look for that soon on the Galapagos Conservancy website.

Tortoises dispersed quickly over the island, eventually covering over 815 hectares (minimum convex polygon area), or about 23% of the vegetated area of Pinta, within the first two months after introduction. Males covered more ground than females with the average maximum displacement from the introduction point over a two month period being 1173 110 meters for males versus 517 114 meters for females. Most of the tortoises do not seem to have settled into a “home range;” they are still making extended movements over short periods of time. In short, they are still exploring the island. This is consistent with other tortoise introduction efforts during which the tortoises did not settle into consistent home ranges until several months had passed after the introduction (Tuberville et al. 2005, Field et al. 2007).

Despite their exploratory behavior, the tortoises do appear to be making habitat choices, especially on an island-wide scale. The most striking example of this is the difference in habitat preference between tortoises with domed carapaces and tortoises with saddle-backed carapaces. Several of the tortoises have made more-or-less linear forays up the elevation gradient towards the peak of the island. The only tortoises that have exhibited this behavior and surpassed 450 meters of elevation have a domed carapace. This result is intuitive as the domed phenotype is more typically associated with higher elevations and habitats dominated by ferns, Zanthoxylem, and Chiococca. The saddle-backed tortoises typically did not exceed an elevation of 450 meters, which elevation corresponds to the limit of the cactus elevation gradient.

The release process appeared to involve no trauma to the tortoises; they appeared to display normal behavior almost immediately after the introduction. We spent 76 hours observing tortoise behavior. Tortoises spent, on average, 25% of the day feeding, which is comparable to other tortoise time activity budgets (Nagy and Medica 1986, Lagarde et al. 2008). We observed tortoises feeding on 28 plant species, but the most preferred species were Opuntia cactus, grasses, and forbs like Lantana and Justicia. Tortoises associated strongly with the cactus in their habitat within the first two weeks after introduction, being more likely to be within 2 meters of a cactus than a random point in the vicinity (x2 = 9.64, df = 1, p = 0.0019). Tortoises fed on fallen adult cactus pads, and also pushed down juvenile cactus to eat the trunks. A few individuals who found recently dead, large, adult cacti did not move from the cactus for weeks, feeding on all of the fallen pads.

While most of the cactus in the introduction area were not fruiting, a few tortoises that moved to the western “saddle” area of the island found fruiting cactus in abundance. We found cactus seeds in these tortoises’ feces, and found seeds of other species in 35% of the fecal samples that we dissected. This suggests the restoration of tortoise-associated seed dispersal phenomenon on Pinta. The tortoises created disturbance in the habitat by making trails as they travelled across the landscape and large swaths of matted down vegetation when they settled into a feeding area. We also observed other normal behaviors like bed-making and mating attempts, suggesting that the tortoises are adapting to their new environment.

Back to the desk

While I've been doing lots of computer work since returning to the US about a week ago, today was the first day that I tried to spend the entire day in my office, sitting at my desk, staring at computer screens... One of the strangest and, I think, most difficult aspects of being a field biologist is that you have to lead this double life: part-time rugged adventurer, part-time intellectual desk jockey. The transitions (field to desk, desk to field) often feel like a moderate case of whiplash with a concussion on top of it. Your body and psyche are forced to move in a completely different direction, and you feel dazed and unsure of yourself. It takes a little time to dig in.

Needless to say, I felt a bit antsy in the office today, but I am excited about working with all of the data we collected. Movement ecology is heading in many interesting directions these days, and I hope to contribute.

-Elizabeth, Syracuse, NY

Movements

A few images to give an idea of where the tortoises were going. The blue outline on the map of Pinta shows the extent of all the tortoise movements on Pinta during the time that we were there. That´s only 2 months and they´ve covered a huge area so far. The green area is where we conducted vegetation and cactus sampling. The red dot is the spot where all of the tortoises were introduced - about half of the tortoises stayed near that point (mostly within the green rectangle) and about half went out to far flung places.

Here are movement patterns of a few of the tortoises that I´ve mentioned. Each dot represents an hourly location starting from the introduction point (red dot). Klever, the tortoise who we had a hard time finding and then had to cut his logger off in the end, has the yellow dots that move straight up towards the top of the island. Wilman, who spent some time in the lava field, is in purple. Milton, who I put up a picture of trying to mount another tortoise, is in green. Johannah, a female who has stayed near the introduction point like most of the other females, is in red overlapping with Milton.

After

The computers here in Puerto Ayora tend to stretch out the pictures, so I will wait to post more pictures with another computer, but I thought it important to post this ¨after¨ picture of the crew (courtesy of Francisco). Smiling faces all around, and you can hardly tell how battered our bodies are. Just looking at it fills me with nostalgia and longing. Half the crew (Francisco and Ben) left the Galapagos this morning, which was a very sad moment for me. Many complicated emotions involved when you have had such an intense experience with a small group of people and gone through so many trials together.

Elizabeth, Santa Cruz