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Lowland Leopard Frog

The leopard frog (Lithobates yavapaiensis) is a small (50 – 86 mm) frog in the ranid family Ranidae native Arizona, New Mexico, Nevada, California, and northern Sonora and Baja California, Mexico in the lower Colorado River basin. They are known to occur across a wide range of habitats and elevations (from 300 - 1,800 m) in streams, lakes, and stock ponds. In Arizona, known populations occur primarily in mid-elevation drainages within mountain ranges in the central and southern parts of the state. Historic populations were known from lower elevation streams and major rivers; however, these populations have primarily disappeared along with those features.

The lowland leopard frog is not federally protected under the Endangered Species Act; however, the species does face pressures from a combination of aquatic habitat loss, increasing non-native species presence, and spreading of disease. Habitat fragmentation and increased groundwater pumping have decreased suitable habitat and reduced dispersal potential. Invasive species such as introduced fishes, bullfrogs, and crayfish are major predators of both larval and adult leopard frogs. Lastly, the chitrid fungus Batrachochytrium dendrobatidis (Bd) has become ubiquitous through the species’ range and can lead to mass mortality events in adult frog populations. County conservation lands include numerous Sky Island mountain canyons where leopard frogs are known to occur. Many of these canyons are ephemeral in nature with limited, disconnected aquatic habitat features during the driest times of year. Observations have shown these features and resident leopard frogs to disappear and reappear with changes in annual stream morphology and sediment transport.

Pima County regularly monitors known leopard frog populations at six ephemeral or perennial streams located on County conservation lands. These efforts occur every three years and are implemented in tandem with the County’s annual wet-dry mapping efforts. Monitoring efforts help determine population persistence within each stream system, and the gain or loss of individual habitat features within each system does not denote extirpation from that system. This species is adapted to highly dynamic systems and have been shown to be resilient to large fluctuations in aquatic habitat availability over time.
Photos by Celeste Andressen (TNC) and Brian Powell (Pima Co)