It is National Invasive Species Week! The week was created to raise awareness for the problems that invasive species create. What is an invasive species? It is a non-native living organism that has been introduced to a new environment by humans that is likely to cause economic harm, environmental harm or harm to human health. Invasive species can be fish, plants, insects, fungus, bacteria, and everything in between.
This week I will highlight invasive species that are causing problems, mostly for amphibians, here and on my social media accounts. Please stay tuned for more!
Common Name: Cajun Chorus Frog Scientific Name: Pseudacris fouquettei Family: Hylidae – Tree Frog family Locations: United States – Arkansas, Louisiana, Missouri, Mississippi, Oklahoma, Texas Size: 1.2 inch (30 mm)
The Cajun Chorus Frog is a relatively new described species, only being described in 2008. Before 2008, it was considered part of the Upland Chorus Frog (Pseudacris feriarum) species complex but was elevated to its own species due to differences in the call and their mitochondria DNA. The frog is part of the Tree Frog family, Hylidae, but they are usually found around ground level.
Breeding for the frog is generally from January to May, following rains. In more southern parts of the range, they can start breeding as early as November. Males will move to temporary ponds and start calling for females. Once the female selects a mate, the male will grasp the female from behind. Then, the female will lay her eggs and the male will then fertilize them. The females will lay between 500 to 1500 eggs at a time. Once the eggs hatch, the tadpoles take 40 to 80 days to complete their metamorphosis. Neither parent provides any parental care for their offspring.
Common Name: Western European Spadefoot Toad, Iberian Spadefoot Toad, Spanish Spadefoot Toad, and Wagler’s Spadefoot Toad Scientific Name:Pelobates cultripes Family:Pelobatidae – European Spadefoot Toad Family Locations: France, Portugal, and Spain Size: 4.9 inches (12.5 cm)
The Western European Spadefoot Toad gets its name due to the spades on its rear feet. The toad uses these spades to burrow down in the ground, over 7 inches deep. They prefer habitat with sandy soils or loosely compact soils since its easier to dig there. The toad is nocturnal so it is hard to find but they often come to the surface after rains.
The Western European Spadefoot Toad breeds from October to May. Males will call from temporary pools to attract females. Females will sometimes call too. Once the female selects a mate, the male will grasp the female frog behind in amplexus. The female will then lay her eggs and the males will fertilize them. Females will lay between 1000 – 4000 eggs. The tadpoles take 4 to 6 months to complete their metamorphism.
The Western Spadefoot Toad is listed as Near Threatened by the International Union for the Conservation of Nature (IUCN) Red List. The habitat they call home is being destroyed for more urban development. Introduced species, such as the Louisiana Crayfish (Procambarus clarkii) and the Eastern Mosquitofish (Gambusia holbrooki), feed on the tadpoles and eggs, decreasing their population.
Common Name: Darien Stubfoot Toad or Toad Mountain Harlequin Frog Scientific Name:Atelopus certus Family:Bufonidae – True Toad family Locations: Panama Male Size: 1.25 inches (32 mm) Female Size: 1.65 inches (42 mm)
The Darien Stubfoot Toad is found in the Darien Pprovince of Panama, hence the name. The genus Atelopus is in deep trouble. The majority of the species are facing extinction due to habitat loss and Chytrid Fungus.
The Darien Stubfoot Toad is listed as critically endangered by the International Union for the Conservation (IUCN) Redlist. The two main reasons for the listing are chytrid fungus and habitat loss. Chytrid Fungus is a deadly pathogen that causes hardening of the frog’s skin, causing them to not be able to breathe. This results in the frog’s death. While the disease hasn’t been observed yet in the Darien Stubfoot Toad, it has been observed in frogs and toads close to them. Habitat loss is another issue for the toad. They only live in a small area that is threatened by development. Luckily, part of the toad’s range is found in the Darién National Park, where they are protected.
Researchers at the Panama Amphibian Rescue and Conservation Project have collected live toads to keep in captivity to preserve the species.
Common Name: Pacific Tree Frog, Pacific Chorus Frog Scientific Name:Pseudacris regilla or Hyliola regilla Family:Hylidae – Tree Frog family Locations: Canada, Mexico, and the United States US Locations: Alaska, Arizona, California, Idaho, Montana, Nevada, Oregon, Utah, and Washington Size: .75 – 2 inches (19 – 50 mm)
Breeding for the frogs happen from November to July with frogs in higher elevations breeding later in the year. The male frogs will come to permanent or non-permanent waters bodies to start calling. The male frog’s breeding call is the typical ribbit that you hear on tv.
The males will highly territorial and will fight other males over breeding areas. Once the female comes and selects a mate, the male will grab her back in amplexus. The female will then lay her eggs and the male will fertilize them. The female will lay between 400 – 750 eggs at a time. Neither parent will provide any care for their offspring. The eggs hatch in 2 to 3 weeks. The tadpoles take 3 months to complete their transformation.
The Pacific Tree Frog was recently split into 3 different species based on DNA, but the analysis wasn’t great and it was merged back together.
The Pacific Tree Frog is the State Frog of Washington
Common Name: Black Legged Poison Dart Frog or Bicolored Dart Frog Scientific Name:Phyllobates bicolor Family:Dendrobatidae – Poison Dart Frog family Locations: Colombia Size: 1.77 – 2.1 inches (45 – 55 mm)
The Black Legged Poison Dart Frogs is one of the most poisonous frogs on earth. They aren’t as poisonous as the Golden Poison Dart Frog (Phyllobates terribilis), the world’s most poisonous frog, but still just 150 micrograms of poison is enough to kill a person. It is one of the three species of poison dart frogs that has been observed to be used to make poison darts by the locals. The natives call the frog, Neará.
They warn predators of their poison with their bright colors. Because they have no natural predators, the frogs are able to be diurnal and move around during the day. The two traits of being duirnal and brightly colored as let to them being introduced in the pet trade. Once the frogs were brought into captivity, they lost their toxicity due to it coming from the native ants they eat. Their large size, for a poison dart frog, also makes them a more ideal pet frog. They have been bred in captivity thus wild caught frogs are rarely seen in the trade in the US. The frogs are social and capable of being housed in groups. They can live up to 20 years under proper care.
Like many other species of Poison Dart Frogs, the Black Legged Poison Dart Frog is a great parent. The frogs will lay their eggs on a leaf or some surface. Once the eggs hatch into tadpoles, the males will carry the tadpoles on their back to a water source for them to grow up in.
Common Name: California Tree Frog or California Chorus Frog Scientific Name:Pseudacris cadaverina or Hyliola cadaverina Family:Hylidae – Tree Frog family Locations: Mexico and the United States (California) Male Size: 1.4 inches (36 mm) Female Size: 1.8 inches (45 mm)
The California Tree Frog can be called the California Chorus Frog due to them being placed in the Chorus Frog genus – Pseudacris. Researchers have proposed moving the frog into the genus Hyliola along with the Pacific Chorus Frog. They are more similar to other Chorus Frogs, in that they aren’t found high in the trees. These frogs like to live in crevices or cavities in boulders along streams. The frogs blend into these boulders with their rough skin and gray / brown color.
Breeding takes place in the streams from February to October. Reproduction for the California Tree Frog is pretty standard. Males will call from the streams to attract potential mates. Once the female selects the mate, the male will grasp her from behind in amplexus. The female then lay her eggs and the male then fertilizes them. Neither parent provide any care for their offspring. The larval period for the tadpoles ranges from 40 – 75 days.
Common Name: Sonoran Green Toad, Pima Green Toad Scientific Name:Anaxyrus retiformis Family:Bufonidae – True Toad Family Locations: Mexico and the United States US Locations: Arizona Size: 1.5 – 2 inches (40 – 49 mm)
The Sonoran Green Toad is known for their yellow / green spots on the dark black background. The toad has lived over 15 years in captivity, which is relatively long for a toad. They are a highly fossorial frog, spending most of their days underground.
Once the summer rains come, the male Sonoran Green Toad comes to temporary filled pools to breed. The males will start to call from grass surrounding the pools to attract females. They are known as explosive breeders due to them only mating for a few days compared to weeks like other frogs. The females will carry the male from the grasses to the water where the females will lay her eggs and the male will fertilize them. The two toads will then part ways and provide no care for the offspring. Females will lay between 5 to 200 eggs. The eggs will hatch into tadpoles in 2 – 3 days. Then, the tadpoles take 2 to 3 weeks to complete their metamorphosis.
Common Name: Oregon Spotted Frog Scientific Name:Rana pretiosa Family:Ranidae – True Frog family Locations: United States and Canada US Locations: California, Oregon, and Washington Size: 1.75 – 4 inches (4.4 – 10.1 cm)
The Oregon Spotted Frog is listed as Vulnerable by the International Union for the Conservation of Nature (IUCN) Red List and as threatened by the United States federal government. The frogs are most likely are gone from California. The two primary threats are introduced species and habitat destruction / alteration. Much of the wetlands that they call home have damaged due to construction of dams and water removal for farms and cities. Some of the remaining habitat has been invaded by the American Bullfrog (Rana catesbeiana) or introduced game fishes. These introduced predators feast on the Oregon Spotted Frog and their tadpoles. Removing these predators would help the frog’s numbers bounce back.
Breeding takes place after the snow melts, generally in February and March at low elevations and May and June at higher elevations. Breeding only lasts 2 to 4 weeks long. Males will gather in the shallows of marshes and lakes at call for the females. Females will select a male to mate. They will then enter the amplexus position and the females will lay their eggs and the male will fertilize. Females lay around 650 eggs. The eggs hatch into tadpoles between 18 and 30 days. The tadpoles then take 110 to 130 days to complete their metamorphosis.
Common Name: Little Grass Frog Scientific Name:Pseudacris ocularis Family:Hylidae – Tree Frog family Locations: United States – Alabama, Florida, Georgia, North Carolina, South Carolina, and Virginia Size: .4 – .7 inches (11 – 20 mm)
The Little Grass Frog is the smallest frog in all of North America. While it is technically in the Tree Frog family – Hylidae, they are not as arboreal as other species of tree frogs. They can still climb up to 5 feet high.
Breeding takes place for the Little Grass Frog from January to September in most of their range but in Florida, they can breed all year long. Breeding generally follows heavy rain events. They lay their eggs in shallow, rain-filled wetlands, ditches, and ponds. Reproduction is pretty standard for the frog. Males will call out from the rain-filled areas, trying to attract females. Females will select a male and then they will mate. The females lay around 100 eggs. How do these females carry all those eggs at their small size? I don’t know. Neither of the parents will perform any care for their offspring.