Chasing Unicorns: Herpetofaunal monitoring of the elusive common lizards of North Bull Island UNESCO reserve, Dublin

Common lizard found on North Bull Island (Photo by Collie Ennis)
Common lizard found on North Bull Island (Photo by Collie Ennis)

North Bull Island is an island located in Dublin Bay in Ireland, about 5 km long and 800 m wide, lying roughly parallel to the shore off Clontarf and facing Sutton. The island, with a sandy beach known as Dollymount Strand running its entire length, is a relatively recent, and inadvertent, result of human intervention in the bay.

The Herpetological Society of Ireland was invited by Dublin City Council to conduct the first ever survey to determine the status of three native reptile and amphibian species that could potentially occur on North Bull Island. With a team of volunteer surveyors, the survey was carried out from March to September 2014 to coincide with the onset of the breeding season of the common frog, smooth newt and the natural activity pattern of the common lizard. Visual sightings were used during frog breeding season and mesh traps were used during smooth newt breeding season to gather data on both species while felt mats were placed around the island to attract basking lizards.

During this survey no sign of the smooth newt was found, a relatively large healthy population of the common frog was noted and only one brief potential sighting of the common lizard was documented, giving the initial impression that any population of common lizards situated there would be quite low and leaving us to believe on many an occasion while trudging through the dunes, that we might be `chasing unicorns’ so to speak, mythical creatures that may not even exist.

From March to august 2015 the survey resumed, this time with a larger emphasis on finding common lizards and their preferred terrain on the island. Higher quality felt mats were purchased and clearly marked as wildlife survey aids to discourage their removal (by well meaning members of the public or otherwise). More volunteers were found with the aid of the TCD zoological society and through an online campaign which greatly increased the ground covered during the survey and the chances of recording a sighting of these shy reptiles.

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One of the felt mats used to attract basking lizards (Photo by Tony Wilson)

These factors coupled with the experience of the previous years survey work led to a drastic increase in the number of common lizards recorded on the island. Survey days were limited to when weather conditions were favourable. More volunteers as expected, covered more ground and the larger ‘wildlife survey’ marked mats were left undisturbed making them a prime location for basking lizards in the early morning sun.

A dramatic increase in the number of common lizards recorded on the island (Photo by Tony Wilson)
A dramatic increase in the number of common lizards recorded on the island (Photo by Tony Wilson)

Most importantly of all the first recording of lizards breeding on the island was documented on the 6th of August with photo documentation taken. This along with sightings of 28 lizards over 5 days of surveying prove that the population is a lot more substantial in certain areas of the island than first thought and hopefully bodes well for their survival in this isolated pocket of Dublin habitat.

Collie Ennis
About Collie Ennis 1 Article
Collie is a science officer with the Herpetological Society of Ireland and an associate of research with TCD Zoology.

3 Comments on Chasing Unicorns: Herpetofaunal monitoring of the elusive common lizards of North Bull Island UNESCO reserve, Dublin

  1. Please remember that this is a licensed survey under national parks and wildlife. Any disruption of the felts and the lizards without a licence is illegal and could jeopardise further surveying. Plenty of opportunities to observe lizards in the dunes or basking on the felts from a distance 🙂

  2. People must remember that these surveys are aimed to safeguard wildlife and conservation, therefore it is not necessary to handle wild animals. You’re trying to preserve wildlife, not add to the human impact.

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