The Sporades... my homeland, and surely my favorite island group in Greece. Before the trip I will go into detail about below, I had visited and done fieldwork on almost all of the islands in this archipelago. However, I had not visited the largest of them all; Skyros, a very unique place that is not exactly a part of the same island chain with Skiathos, Skopelos and Alonissos, but still shares many similarities with them and is regarded by most as an island of the Northern Sporades. In fact, this island is divided into two distinct parts based on its vegetation. The northern half is pristine, fertile, covered by lush green pine forests and holds lots of freshwater, while the southern half is an unhospitable semi-desert with rocky mountains. A very interesting island for sure. I had been planning a visit to Skyros for quite some time, and it finally happened in the first week of October 2023. Some interesting notes can be found in the end of the article.
Athens
Although I dislike this city so much, I decided to head to Athens for a day before taking the bus to Kymi. This led to a quick spontaneous outing outside Athens with Charis Kouelis, where we flipped some cover and hiked a wetland area. We found green toad (Bufotes viridis), marsh frogs (Pelophylax kurtmuelleri), house gecko (Hemidactylus turcicus), balkan green lizard (Lacerta trilineata), ocellated skinks (Chalcides ocellatus) and a single montpellier snake (Malpolon insignitus) that vanished into the vegetation. The usual suspects in Attica.
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| Ocellated skink (Chalcides ocellatus) |
Skyros
Skyros was easy to reach from Athens. Eirini Mandaraka and I had planned to meet at the bus station about 30-40 minutes before departure, but due to me not understanding just how bad traffic can get in Athens, the taxi ride there lasted a good 35 mins and I got there moments before the bus left. Anyway, after about 2 and a half hours on the bus to Kymi port and about 2 hours on the ship we set foot on Skyros at exactly 19:55 in the evening; it was pitch black darkness. We quickly got some groceries from Linaria and our host gave us a ride to our room in Acherounes bay, a beautiful and somewhat quiet place at the western part of the island. On the same night we decided to do a short outing in search for cat snakes, but soon returned home as it was cold and windy. We found a dozen house geckos (Hemidactylus turcicus), as well as a balkan terrapin (Mauremys rivulata) and a couple of marsh frogs (Pelophylax sp.) at the stream near our room.
On the next day, we woke up really early, though the sun didn't shine until about 7:40 or so due to the hills surrounding our area. Nevertheless, we walked around our accomodation as well as up the main road of Acherounes plain, and we found our first Skyros wall lizards (Podarcis gaigeae), which was a species we really wanted to see, as well as an adult Balkan green lizard (Lacerta trilineata). Not much else was seen that morning, but we photographed the terrapins and frogs that inhabited the stream next to where we stayed. That afternoon, we took the bus from Linaria to Chora, the main town of Skyros, where we did some sightseeing, ate some food and picked up our rental bikes, with which we returned to Acherounes. It was mainly a day of doing tourist stuff.
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| The main road of the Acherounes area. The grassy edges are habitat to Skyros wall lizards (Podarcis gaigeae) and balkan green lizards (Lacerta trilineata). |
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| Female Skyros wall lizard (Podarcis gaigeae). (C) Eirini |
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| Female Skyros wall lizard (Podarcis gaigeae). (C) Eirini |
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| Marsh frog (Pelophylax sp.). (C) Eirini |
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| Balkan terrapin (Mauremys rivulata). (C) Eirini |
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| Balkan terrapin (Mauremys rivulata). (C) Eirini |
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| Where we stayed |
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| Linaria harbor |
As we now had our bikes and getting anywhere was going to be easier, we decided to head to a large artificial wetland located near Chora. This massive water reservoir is not in operation and serves as a great habitat for lots of wildlife, including birds, dragonflies, frogs and grass snakes. Getting there was really painful as most of the route was uphill, but we finally reached the place somewhat early in the morning. I flipped some rocks on the way there and found a single sleeping Skyros wall lizard (Podarcis gaigeae). At the reservoir, we noticed several smaller ponds that were inhabited by dozens of marsh frogs (Pelophylax sp.). We also got to hear some calls. At a small stream that supplies the reservoir with water, I heard the cries of a marsh frog and followed it to discover that a grass snake (Natrix natrix) had caught it and was trying to eat it. Although the frog managed to escape, I caught the snake for a quick photoshoot. It was a young melanistic individual and our first snake of the trip! The heat afterwards was intense, so we returned to our room and stayed there for the rest of the day before heading to Chora for dinner.
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| The water dam of Skyros |
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| One of the ponds, home to several marsh frogs |
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| Violet dropwing (Trithemis annulata) (C) Eirini |
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| Marsh frog (Pelophylax sp.) (C) Eirini |
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| Melanistic grass snake (Natrix natrix) |
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| Melanistic grass snake (Natrix natrix) |
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| Male Skyros wall lizard (Podarcis gaigeae) (C) Eirini |
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| Skyros wall lizard (Podarcis gaigeae) |
On day 3 we stayed in the room during the morning, in order to have enough energy to head towards some spots in the wider Molos area later in the day. Before we left, however, Eirini spotted a juvenile grass snake in the small stream next to our room, but we were unable to photograph it. So, in the afternoon we started the 9,3km ride to our first spot. This location was a mostly dry stream hinted to us as a good spot for quatuorlineata and Natrix. Indeed, just as we got there, we found a large-ish stripeless morph grass snake moving through the grass, and managed to catch it. It was not a very cooperative individual, so the photoshoot lasted for quite some time. When we left the first spot, it was already late, so during the rest of the afternoon we started flipping stones and only found some Kotschy's geckos (Mediodactylus kotschyi) and an old DOR adult four-lined snake (Elaphe quautorlineata scyrensis) - a really unfortunate sight, but an interesting record nevertheless. We then went to Chora and dropped our bikes off at the rental shop.
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| View towards the rocky mountains of southern Skyros |
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| Grass snake (Natrix natrix) |
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| Grass snake (Natrix natrix) |
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| Grass snake (Natrix natrix) (C) Eirini |
We spent our final morning in the Acherounes area, with the goal of photographing the lizards, terrapins and frogs that inhabited the limited habitat around our room. We managed to get some nice in-situs, especially of Skyros wall lizards. We also found and photographed a tiny juvenile Balkan green lizard (Lacerta trilineata). At noon, we packed our stuff, ate some lunch at Linaria and finally boarded the ferry to Kymi.
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| Female Skyros wall lizard (Podarcis gaigeae) |
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| One of the fields that border the stream of Acherounes |
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| Marsh frog (Pelophylax sp.) (C) Eirini |
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| Skyros wall lizard (Podarcis gaigeae) (C) Eirini |
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| Marsh frog (Pelophylax sp.) (C) Eirini |
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Marsh frog (Pelophylax sp.) (C) Eirini
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| Juvenile Balkan green lizard (Lacerta trilineata) that was foraging at the stream (C) Eirini |
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| Balkan terrapins (Mauremys rivulata) (C) Eirini |
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| Balkan terrapins (Mauremys rivulata) (C) Eirini |
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| Skyros wall lizard (Podarcis gaigeae) |
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| Skyros wall lizard (Podarcis gaigeae) |
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| The legendary F/B Achilleas, on the way back to Kymi the morning before we departed. On the right is Valaxa islet. (C) Eirini |
Overall, herping on Skyros proved to be hard, especially without a car and during such a bad time of the year. More time was spent getting to know the island and resting than herping, but we still found some of our targets and made several nice observations, while I also had the opportunity to test my new camera in the field. One could say it was more of a recon mission!
Preliminary insights
As I have conducted fieldwork in all of the Northern Sporades, as well in a large part of Euboea island and some of its surrounding islets, it is fair to say that a visit to Skyros was much needed in order to understand the biogeography and ecology of this region better. Here are some thoughts and observations:
- The marsh frogs of Skyros are of particular interest. As the island has been insularly isolated for approx. 4.5-5my, they had the time to diverge into, perhaps, an endemic clade. Their calls are hesitant and short, and mainly composed of squeaks and individual croaks. Morphologically, they are mainly of a monotone brown or grey color with dark blotches. Bright green is common on Euboea and occurs somewhat less often on Skiathos, but seems to be completely absent on Skyros. Similarly, individuals from Skyros do not exhibit the light vertebral line that often occurs in the P. ridibundus-complex. Therefore, I refer to them simply as Pelophylax sp. Upcoming molecular studies are expected to shed light into the taxonomy of marsh frogs in Greece.
- The Skyros wall lizards are descendants of an ancestral form of P. tauricus that colonized Euboea and then crossed into Skyros before its seperation from the mainland. However, these lizards do not look anything like P. tauricus, and seem to have evolved into a form that is better adapted for an insular lifestyle. They closely resemble insular populations of P. erhardii in shape, size and behavior - a case of convergent evolution?
- Grass snakes appear to be common across the northern half of Skyros and are at least to some degree terrestrial, perhaps supplementing their diet with lizards, insects and rodents. My hypothesis is that this happens mainly in seasonal streams and wetlands (e.g.: the stream near Molos was mostly dry at the time of our visit), where during the dry months grass snakes become crepuscular and forage in phrygana, maquis, olive groves, gardens, etc, while grass snakes around year-round water sources with healthy Pelophylax numbers (e.g. the water dam) will mainly take frogs and their tadpoles.
- There is a high degree of aberration in the grass snakes of Skyros, which are represented by five phenotypes; uniform charcoal, striped charcoal, picturata, striped persa and stripeless persa. The melanistic forms are seemingly more common.
- Balkan green lizards are somewhat uncommon and heavily outnumbered by P. gaigeae. This is similar to the cases of Skopelos and Alonissos, but not Skiathos (which lacks Podarcis) and Euboea (where P. muralis and P. erhardii are more scarce and localized).
- Skyros is a very large island with a really wide selection of habitats, capable of supporting many herpetofauna species. Despite the abundance of resources, however, the island has been insularly isolated for a long time. This explains the lack of herpetofauna diversity, as many more species likely reached the island before its seperation from the mainland during the Late Miocene epoch, but subsequently went extinct during the millennia for different ecological reasons. The 5 million years of isolation also account for the presence of endemic taxa.
Nonetheless, a single visit is not enough for a clear understanding of the herpetological and ecological framework of Skyros, and I am extremely eager to go back and perhaps visit some of the satellite islets as well!
Species seen
Skyros:
Four-lined snake (Elaphe quatuorlineata scyrensis) DOR
Grass snake (Natrix natrix moreotica)
Kotschy's gecko (Mediodactylus kotschyi ssp.)
Mediterranean house gecko (Hemidactylus turcicus)
Skyros wall lizard (Podarcis gaigeae)
Balkan green lizard (Lacerta trilineata)
Balkan terrapin (Mauremys rivulata)
Marsh frog (Pelophylax sp.)
Attica:
Eastern montpellier snake (Malpolon insignitus)
Balkan green lizard (Lacerta trilineata)
Ocellated skink (Chalcides ocellatus)
Mediterranean house gecko (Hemidactylus turcicus)
Green toad (Bufotes viridis)
Balkan marsh frog (Pelophylax kurtmuelleri)
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