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DIE EIDECHSE L@CERTIDAE 1. Herpetoculture 2. Trip reports 3. Release and drifting 4. The Balearics 5. Other articles Edition Lacertidae Herpetoscriptum Herpetologisches Antiquariat Bibliografie Poster

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13 to The Balearics related L@certidae articles available...

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Cirer, A.M. & Berg, M.P. van den (2025) - Estimation of lizard density in Podarcis pityusensis island populations over time, with special attention to the correct naming of the islets. - L@CERTIDAE (Eidechsen Online), 2025 [1]: 1-187.
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In this study we compile data regarding lizard densities of the island populations of the Ibiza wall lizard, Podarcis pityusensis, which can serve as a baseline for future research and control of the invasive snakes, and in particular the horseshoe whip snake Hemorrhois hippocrepis, in the Pityusic Islands. Special attention has been given to the correct official spelling of 96 locations of which 89 are real rocks, islets and islands. For each island a short description, toponymy, faunal and floral aspects and some herpetological history is given, and a lizard density value was assigned. The results are very disturbing, with two confirmed- and three most likely extinct island populations of Podarcis pityusensis, and we call for coordinated action.
Berg, M.P. van den & Zawadzki, M. (2023) - Goodbye to innocence – The silent death and disappearing of the Ibiza wall lizard Podarcis pityusensis (BOSCÁ, 1883) caused by introduced snakes. - L@CERTIDAE (Eidechsen Online), 2023 [5]: 73-87.
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The Ibiza wall lizard Podarcis pityusensis (Boscá, 1883) is the only living endemic land vertebrate of the Pityusic Islands. It has not only become the symbol of these islands, but also plays a significant role in the sub-archipelago’s ecosystem. For centuries, Ibiza was famous for being completely free of snakes. Unfortunately, this is no longer the case. The introduction of three snake species on Ibiza has changed the natural balance of the island. The horseshoe whip snake Hemorrhois hippocrepis is of particular concern as it is threatening to wipe out the native lizards. Not only does Podarcis pityusensis disappear at a worrying rate on Ibiza: the population from the little offshore island Illot de S’Oro, representing the subspecies Podarcis pityusensis hortae, has already become extinct due to this new predator.
Berg, M.P. van den & Zawadzki, M. (2023) - What goes up must come down – The discovery of a new island population of Podarcis pityusensis (Boscá, 1883) in the North of Ibiza by use of an aerial drone. - L@CERTIDAE (Eidechsen Online), 2023 [3]: 22-27.
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Unmanned aerial vehicles (colloquially known as drones) equipped with a high-definition camera have a wide range of applications in biological research. In this article we report on our experiences using a drone to explore the surface of hard to access small islands in the North of Ibiza (Balearic Islands, Spain) for possible occurrences of lizard populations. On one of these small and unnamed islets that we call “Escull a Punta de Llevant” we detected a hitherto unknown population of Podarcis pityusensis.
Zawadzki, M. (2020) - Success model “island lizard” – or rather a bleak future for the Ibiza wall lizard Podarcis pityusensis (BOSCÁ, 1883)? - L@CERTIDAE (Eidechsen Online), 2020 [3]: 19–41.
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The Ibiza wall lizard, Podarcis pityusensis is the only endemic land vertebrate of the Pityusic Islands. It inhabits the two main islands Ibiza and Formentera as well as the vast majority of the offshore small islands. When humans first arrived at the islands, they brought with them a handful of foreign predators, such as genets, beech martens, rats, and feral cats – all lizard predators. Podarcis pityusensis is fully protected by national and international legislation and listed in Annex II of the Bern Convention and in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). It is declared as “Near Threatened” by the IUCN (2009). However, some of the populations are very much reduced, endangered or on the verge of extinction as they are threatened by illegal collection, disturbance by visitors, introduction of cats and rats to the islands, and accidental poisoning with bait left for seagulls. The recent introductions of three snake species on Ibiza and Formentera are of particular concern. The Montpellier snake (Malpolon monspessulanus) has not been caught on the islands since 2010. The horseshoe whip snake (Hemorrhois hippocrepis) has shifted its diet towards lizards, with the native Ibiza wall lizard, representing 55.4 % of the observed prey. A similar dietary shift is probably occurring with the ladder snake (Rhinechis scalaris) in Formentera, as a preliminary study shows that more than half of its prey is constituted by Podarcis pityusensis (HINCKLEY et al. 2017). The effect of predation may seriously threaten the lizards in the main islands and the arrival of snakes in the surrounding islands may produce a catastrophic and irrecoverable event for lizard populations as they would be the only available prey.
Berg, M.P. van den & Zawadzki, M. (2017) - Spring 2017 - Herpetological trip to Ibiza (Spain) - with introduction of a new population of Podarcis pityusensis. - L@CERTIDAE, 2017 [5]: 139-167.
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This is already our seventh report in a series on our whereabouts while collecting data for a future revision of the present subspecific order of the endemic Balearic sisterspecies Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883) (VAN DEN BERG & ZAWADZKI 2011 ; VAN DEN BERG et al. 2013 ; VAN DEN BERG et al. 2014a ; VAN DEN BERG et al. 2014b ; VAN DEN BERG et al. 2015 ; VAN DEN BERG et al. 2016). During this trip from the 8th until the 21st of April 2017, we were able to collect data at some mainland Ibiza locations, as well as on the following adjacent islands: Caragoler, Escull d’en Terra, Negra Norte, Vedranell, Conillera and Ses Margalides. We continue with the ventral coloration as a possible determining key as introduced in our 2014 trip report (VAN DEN BERG et al. 2014b). Images of the anal shields are presented of each lizard for purposes of illustration. Also we report on a new approach of assessing small islands, which have been considered without lizards in the past, or haven’t been considered at all, for the possibility of hosting a lizard population. Investigating these “uninhabited” small islands resulted in one new to describe population of Podarcis pityusensis, and a proven occurrence of a lizard population on another small island.
Berg, M.P. van den & Zawadzki, M. & Kroniger, M. (2016) - Spring 2016 - Herpetological trip to Ibiza (Spain). - L@CERTIDAE, 2016 [3]: 23-70.
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This is already our sixth report in a series on our whereabouts while collecting data for a future revision of the present subspecific order of the endemic Balearic sisterspecies Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883), which data are stored in our database at www.pityusensis.nl (VAN DEN BERG & ZAWADZKI 2011 ; VAN DEN BERG et al. 2013 ; VAN DEN BERG et al. 2014a ; VAN DEN BERG et al. 2014b ; VAN DEN BERG et al. 2015). During this trip from the 27th of March until the 9th of April 2016, we were able to collect data at some mainland Ibiza locations, as well as on the following adjacent islands: Sa Mesquida, S’Hort, S’Illeta de Cala Salada, Vedranell, Rates, Bleda Plana, Murada, Bleda Na Bosc and S’Espardell de S’Espartar. We continue with the ventral coloration as a possible determining key as introduced in our 2014 trip report (VAN DEN BERG et al. 2014b). Images of the anal shields are presented of each lizard for purposes of illustration.
Berg, M.P. van den & Zawadzki, M. & Kroniger, M. (2016) - Ontogenetic color change in Podarcis pityusensis - first observations. - L@CERTIDAE, 2016 [2]: 10-22.
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A short introduction and a hypothetical model concerning color formation in lacertid lizards is presented. Thereafter we observe and discus the ontogenetic changes in a single female captive bred Podarcis pityusensis lizard from Formentera (Balearic islands/Spain). Striking transformations concerning coloration are observed.
Zawadzki, M. & Berg, M.P. van den (2015) - Lizards in the mist - and a shot in the dark. The search for the terra typica of Podarcis lilfordi carbonerae PÉREZ-MELLADO & SALVADOR, 1988. - L@CERTIDAE, 2015 [8]: 160-191.
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As a result of their taxonomical study of the populations of the Balearic lizard of Menorca Pérez-Mellado & Salvador (1988) described three new subspecies of Podarcis lilfordi. The type series of one of them, Podarcis lilfordi carbonerae, had been collected on an island called “Isla Carbonera” in 1933. The fact that their describers could not find this islet on any map, but did not hesitate to describe these lizards as a new subspecies, was not very reasonable and surely contributed to the mystery that should surround this subspecies from now on. But it was not this fact alone that casted a bad light on this taxonomic revision, because in-depth analyses revealed more awkward mistakes. Even the rediscovery of Podarcis lilfordi carbonerae by Pérez-Mellado et al. (2002) was only based on assumptions but did not contain any scientific proof. In this paper we give new information on the possible terra typica of Podarcis lilfordi carbonerae by introducing the Illa de Ses Mones. Because neither the En Carbó nor the Ses Mones lizards can be separated from the populations of the two nearby islands Illa Gran d’Addaia and Illa Petit d’Addaia by means of coloration or meristic and metric characters, we consider Podarcis lilfordi carbonerae Pérez-Mellado & Salvador, 1988 as a synonym of Podarcis lilfordi addayae (Eisentraut, 1928).
Berg, M.P. van den & Zawadzki, M. & Kroniger, M. (2015) - New remarkable observations on the population of Podarcis pityusensis at Ses Margalides (Ibiza/Spain). - L@CERTIDAE, 2015 [5]: 90-127.
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We report on our visit to the largest of the Ses Margalides islands during our spring 2015 herpetological trip to Ibiza. The island habitat is described, the herpetological history of the Podarcis pityusensis population on this island is summarized, and additional data of this population is given. Among this new data are pictures of red bellied green backed lizards, blue lizards, and a description of a light gray color morph, all previously unknown to this population.
Berg, M.P. van den (2015) - Estimating recent divergence time in populations of Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883) using NAVIONICS SonarCharts™. - L@CERTIDAE, 2015 [2]: 6-22.
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New data on estimated divergence times of the populations of lacertid lizards in the Balearic Islands are provided in this second update of the October 2011 article: Estimating recent divergence time in populations of Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883) (VAN DEN BERG 2011), which received its first update May 2012. In most cases better estimations of divergence times were available by using the NAVIONICS SonarCharts™webapp.
Berg, M.P. van den & Zawadzki, M. & Kroniger, M. (2014) - Spring 2014 - Herpetological trip to Ibiza (Spain). - L@CERTIDAE, 2014 [6]: 53-100.
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This is our fourth report in a series on our whereabouts while collecting data for a future revision of the present subspecific order of the endemic Balearic sisterspecies Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883), which data are stored in our free accessible database at www.pityusensis.nl (VAN DEN BERG & ZAWADZKI 2011 ; VAN DEN BERG et al. 2013 ; VAN DEN BERG et al. 2014). During this trip from the 22nd of May untill the 6th of June 2014, we were able to collect data on various mainland Ibiza locations, as well as the following adjacent islands; Tagomago, Dau Gran, Negra Llevant, Bosc de Conillera, Conillera, Espartar, S’Espardell de S’Espartar, and Escui de S’Espartar. We also visited Escui de Cala d’Hort, and can confirm this rock is without lizards. We also introduce a simplified representation of the ventral coloration as a possible determining key.
Berg, M.P. van den & Zawadzki, M. & Kroniger, M. (2014) - 2013 - Herpetological trips to the Balearic Islands (Spain). - L@CERTIDAE, 2014 [3]: 17-34.
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More than three decades of fascination for the endemic Balearic sisterspecies Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883), resulted in 30 trips (1980-2013) to the home of these lacertid lizards, in which we studied their ethology as well as their distribution and geographical differences in pattern and coloration. In comparison to prior scientific studies that led to an inflationary description of subspecies, we often found wide variations within populations and their subspecific characteristics. The question “To be distinct, or not to be distinct” is, to our opinion, not answered correctly in most cases. In order to gather data for a future revision of the present subspecific order, we started in 2011 to collect data of these lizards in a structured way, and storing this data in a free accessible database (www.pityusensis.nl). Later in 2011 we enhanced our dataset by gathering tissue samples of the lizards, using the non invasive technique of buccal swabbing, for future accompanied DNA research.
Berg, M.P. van den & Zawadzki, M. & Kroniger, M. (2013) - Herpetological trip to Menorca (Balearics, Spain): April 30 till May 11, 2012. - L@CERTIDAE, 2013 [5]: 25-76.
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We report on our observations on Podarcis lilfordi (GÜNTHER, 1874) and other Menorcan herpetofauna during our 12 day trip to Menorca (Balearics, Spain). 13 populations of Podarcis lilfordi were surveyed, 101 specimens were measured and photographed in detail, from which 84 specimens were “buccal-swabbed” for DNA samples. The subspecific status of Hemidactylus turcicus spinalis from Addaia Gran is discussed and rejected.

Farbbildung bei Echten Eidechsen
Color formation in lacertidae
© 2016 MARTEN VAN DEN BERG, MICHAEL KRONIGER & MIKE ZAWADZKI

2011 Herpetological trip to Parc natural de s’Albufera des Grau
© 2011 MARTEN VAN DEN BERG & MIKE ZAWADZKI

Estimating recent divergence time in populations of Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883)
© 2011 MARTEN VAN DEN BERG

Vortrag Jahrestagung AG Lacertiden - Wiederentdeckung und Sympatrie auf Ses Mones
© 2011 MIKE ZAWADZKI & MARTEN VAN DEN BERG

Cold-blooded Cannibals - Observations on cannibalistic egg eating and predation on juveniles within Podarcis pityusensis
© 2011 NATHAN DAPPEN

Remarks on Podarcis lilfordi rodriquezi (L. MÜLLER, 1927), an extinct subspecies of the Balearic lizard
© 2010 MIKE ZAWADZKI

Small, smaller, smallst - About the smallest islet populations of Podarcis pityusensis and Podarcis lilfordi, with first record of two new very small islet populations
© 2010 MARTEN VAN DEN BERG & MIKE ZAWADZKI

Wiederentdeckung einer ausgestorben geglaubten Population der Baleareneidechse, Podarcis lilfordi (GÜNTHER, 1874) auf der Illa de Ses Mones (Balearen, Menorca, Spanien) in Sympatrie mit der Ruineneidechse, Podarcis siculus (RAFINESQUE-SCHMALTZ, 1810)
© 2010 MARTEN VAN DEN BERG & MIKE ZAWADZKI

Two new islet locations of Podarcis pityusensis formenterae near Formentera island (Spain, Balearics)
© 2010 MARTEN VAN DEN BERG

Beobachtungen an einer Population von Podarcis lilfordi (GÜNTHER, 1874) auf der ehemaligen Insel Frailes bei Colónia de Sant Jordi, SW-Mallorca (Spanien, Balearen)
© 2010 MIKE ZAWADZKI