Creatures in Crisis
Photograph of Eleutherodactylus grandis (Eleutherodactylus grandis), recorded as Endangered
Photo: Tom Devitt, CC BY 4.0, via Wikimedia Commons.

Endangered

Eleutherodactylus grandis

Eleutherodactylus grandis

The Pedregal frog, or great peeping frog (Eleutherodactylus grandis), is a small whistling frog of the volcanic lava rock in and around southern Mexico City. The IUCN Red List rated it Endangered in 2020, down from Critically Endangered in 2004. It has no tadpole stage, and most of its habitat has been built over.

Status
Endangered
Red List assessment
2020, criteria B1ab(iii)
Scientific name
Eleutherodactylus grandis
Taxonomy
Amphibia · Anura · Eleutherodactylidae · Eleutherodactylus

How to recognise it

It is a tiny frog, with a maximum length of about six centimetres according to a 2025 news report in Posta. Females are usually a few millimetres longer than males.

You are far more likely to hear this frog than see it. Males give a short, single-note whistle, repeated about one to six times a minute. A 2016 study found that each male's pitch changes very little, which Serrano suggests may help frogs recognise each other.

Where it lives

The frog is endemic to Mexico. It is known from the Pedregal del Xitle, the lava flow left by the Xitle volcano, in the south of Mexico City. The IUCN gives its elevation as 2,200 to 2,682 metres, with an extent of occurrence of 118 square kilometres. It adds that recent surveys found the frog at several other localities in the city and the State of Mexico, and that it is likely wherever lava rock occurs.

Its best-known strongholds are protected areas in and around the city, including the Reserva Ecológica del Pedregal de San Ángel on the university campus, the Ecoguardas park and the Parque Ecológico de la Ciudad de México. It lives among large, solid rocks, and avoids crumbly volcanic soil where shifting stones could crush it. The IUCN says it historically lived in dry shrubland, but now occurs mainly in urban areas.

Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.

How it lives

The IUCN says it breeds by direct development, with no free-swimming tadpoles. Males call from bare rock and from clumps of grass, mostly from late May to mid-August. Calling peaks at the start of the rainy season and is stronger after rainy days.

Tracking over 20 nights found that males moved less than two metres on average. Many vanish from their calling rock within two or three nights, and where they go is unknown. A 2023 review put the home range of one frog at about 0.4 square metres, citing a 2022 thesis.

Why it is in trouble

Mexico City grew over most of the lava field. The IUCN describes the Pedregal reserve as an isolated vegetation fragment of 160 hectares with no natural corridors. A 2016 paper in Revista Mexicana de Biodiversidad put the frog's intact range at under 10 square kilometres. The 2025 Posta report said the ecosystem had shrunk from more than 80 square kilometres to about 13. The two figures differ, but both describe a very small remnant.

The Red List scores housing, roads, recreation and acid rain as ongoing, low-impact threats, and records a continuing decline in the area the frog occupies. Its population trend is decreasing.

What is being done

The frog occurs in the Pedregal reserve and is protected in Mexico under the Special Protection category. The 2020 assessment lists site management, species recovery and habitat protection among the actions needed, including a recovery programme and species management plans, and calls for survey work on its current status.

The IUCN calls the species not particularly common and difficult to collect, though more often found in the rainy season, from June to October. A 2023 review, citing a 2022 study, says it appears relatively abundant in the few lava-field reserves that remain. A group of biologists studied the frog in 2015 with support from the Conservation Leadership Programme, according to the Posta report.

Sources

Written for this catalog in our own words from the sources below, checked against them on 12 November 2026. Population figures are estimates and carry the year they were made. Status and assessment year: IUCN. 2026. The IUCN Red List of Threatened Species. Version 2026-1. iucnredlist.org.

Photograph via Wikimedia Commons. Wikipedia · Wikidata · IUCN Red List.

Same genus

Photograph of Dwarf coqui (Eleutherodactylus unicolor), recorded as Critically EndangeredCR

Dwarf coqui

Eleutherodactylus unicolor
Photograph of Eleutherodactylus albipes (Eleutherodactylus albipes), recorded as Critically EndangeredCR

Eleutherodactylus albipes

Eleutherodactylus albipes
Photograph of Eleutherodactylus diplasius (Eleutherodactylus diplasius), recorded as Critically EndangeredCR

Eleutherodactylus diplasius

Eleutherodactylus diplasius
Photograph of Eleutherodactylus orientalis (Eleutherodactylus orientalis), recorded as Critically EndangeredCR

Eleutherodactylus orientalis

Eleutherodactylus orientalis

Quick answers

Where can you find the Pedregal frog?
Mainly on the Xitle lava field in southern Mexico City, with other lava-rock sites in the city and the State of Mexico. It occurs in the Pedregal de San Ángel reserve and the Ecoguardas park. Males call mainly from late May to mid-August.
Why is the Pedregal frog Endangered?
Its habitat is a lava field that Mexico City has largely built over. Estimates of what remains range from under 10 to about 13 square kilometres. The Red List records a continuing decline in habitat area and a decreasing population.
Does the Pedregal frog have tadpoles?
No. The IUCN says it breeds by direct development, so young frogs hatch from eggs on land rather than as swimming tadpoles. This suits the dry, rocky lava habitat where it lives.
How many Pedregal frogs are left?
No total population count exists. The IUCN calls it not particularly common and hard to collect, while a 2023 review says it seems relatively abundant in the few remaining reserves. The Red List trend is decreasing, and its status was last assessed in 2020.