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June 13th, 2024
Creature Feature: Arroyo Toad
Author: Rachel Noriega
Hop into summer with the arroyo toad! Arroyo toads are terrestrial toads that range along the coast from Central California, US to Baja, Mexico. These toads are on the U.S. endangered species list and have been extirpated from an estimated 65% of their former range. In May, I attended a workshop to learn about arroyo toad ecology and how to conduct presence surveys and here are some key takeaways I learned.
Arroyo toad habitat requirements line up nicely with where humans like to develop in the southwestern US. Arroyo toads prefer semi-arid climates (few extreme temperatures), low gradient drainage with open sandy terraces, braided channels with non-perennial flow, and low water flow rates. Like other toads, arroyo toads are terrestrial as adults, but require water to breed. Arroyo toads are nocturnal and spend most of their day in underground burrows with the exception of breeding season which is approximately March 15 to July 1. Breeding season is the best time to conduct a presence survey and knowing arroyo toad ecology and identification markers is important to conducting surveys in the safest manner for the species.
Identifying an Arroyo toad can sometimes be difficult, but some important characteristics to look for are the V-shaped light-colored strip that runs on top of its head between its eyes, the presence of horizontal pupils, parotid glands behind the eyes that go from a light to dark color gradient, and how they move: they hop, unlike some toads.
If you encounter an arroyo toad, it’s important to observe with your eyes only. These toads can enter a state of aestivation during the drought season. Aestivation is a form of hibernation that allows the toads to maintain their hydration and if picked up this can cause the toad to empty its bladder and result in death. Also, you should not handle or harass (disturb) any endangered species without a permit from the U.S. Fish and Wildlife Service.
Arroyo toads are small: a full-grown adult ranges from 2-3 inches a juvenile toad ranges from 0.4 to 1.6 inches. This diminutive size can also complicate the survey process and is why specialized training on how to conduct presence surveys safely and effectively is imperative.
Their small size is also why it’s important to stay on trails, particularly during breeding season. As shown in the picture Arroyo toads do a great job of blending in and if you travel off trail, you might accidentally harm one.
Arroyo Toad – Great Ecology
