Population status of the Floreana racer (Pseudalsophis biserialis biserialis (Günther, 1860)) on islets off the coast of Floreana Island, Galápagos Islands, Ecuador

Luis Ortiz-Catedral^{1, *} , Eli Christian¹, Danny Rueda², Christian Sevilla³, Jennifer C. Daltry^4,5

Affiliations:
1 The Snake Pit – Island Vertebrates Lab, School of Natural and Computational Sciences,
Massey University, Private Bag 102904, North Shore Mail Centre, Auckland, New Zealand.
2 Galápagos Life Fund, Calle Matazarnos 63 y Floreana, barrio Pelikan Bay, Puerto Ayora,
Santa Cruz, Islas Galápagos, Ecuador
3 Dirección de Ecosistemas, Dirección del Parque Nacional Galápagos, Av. Charles Darwin, S/N Puerto Ayora, Santa Cruz, Islas Galápagos, Ecuador
3 Fauna and Flora, David Attenborough Building, Pembroke Street, Cambridge CB2 3QZ, United Kingdom
4 Re:wild, PO Box 129, Austin, TX 78767, USA.
* Corresponding author: luis.ortiz.catedral@gmail.com

Received: 24 July 2024 | Accepted: 11 July 2025 | Published: 21 October 2025
Senior Editor: Marleen Baling
https://doi.org/10.34074/pibdiv.003107

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Abstract
The Floreana racer (Pseudalsophis biserialis biserialis) is a subspecies of the Eastern Galápagos racer, formerly present in the lowlands of Floreana Island but confined to only two localities since the late 1800s: Champion Islet and Gardner-by-Floreana, both free of introduced rodents and cats. We conducted the first population assessment for the subspecies by using a capture-mark-recapture method of tagged individuals. We captured and measured 123 individuals, and estimated an approximate density of 12 adult and subadult individuals per ha on Champion Islet, and 14 per ha on Gardner-by-Floreana. Based on our results, we calculate that the global population of this subspecies is approximately 1000–1500 individuals. The current population on Champion Islet is likely to be very small, possibly fewer than 100 individuals. Strict quarantine to prevent the accidental introduction of invasive alien species to both islets is paramount. Our results indicate that both islets hold sufficient numbers of Floreana racers to assist in the translocation plans for the species back to the lowlands of Floreana Island as part of the ecological restoration in the Galápagos Islands.

Cite as:
Ortiz-Catedral, L., Christian, E., Rueda, D., Sevilla, C., Daltry, J. C. (2025). Population status of the Floreana racer (Pseudalsophis biserialis biserialis (Günther, 1860)) on islets off the coast of Floreana Island, Galápagos Islands, Ecuador. Perspectives in Biodiversity, 3(1): 76–82. https://doi.org/10.34074/pibdiv.003107