stgiery's Identifications

The frogs are out in great numbers night and day at the small pond and other wet areas of the park and many egg masses have already been laid. The attached photo is of 3 tenacious males that refuse to release the female which I assume had become a casualty of love. I picked up the writhing, croaking cluster and was surprised that she was still "kicking". She even laid a few eggs in my hand.

Scientific and Common Name

The organism observed is called Lithobates pipiens, or more commonly known as the northern leopard frog.

Habitat and Geographic Range

A majority of Lithobates pipiens’ general population is present in northern North America, but their presence lacks on the Pacific Coast (National Geographic Society, n.d.). In Canada, they have been found to exist from British Columbia to the Maritimes and can range south to California and New Mexico (in reduced numbers) and east towards South Carolina in the United States (Stebbins & Cohen, 1995). However, the last of presence on the Pacific Coast can be due to the introduction of non-native species, such as bullfrogs (Rana caesbeiana) and the increased competition or predation preceding the introduction of these species (Hayes & Jennings, 1986).

They reside in both aquatic and terrestrial habitats. Conditions of aquatic habitats that Lithobates pipens occupy can range depending on different environmental conditions, such as temperature (Ohanhanian & Paige, 2004). Shallow water with an abundance of vegetation and an absence in predatory fish generally provide the best conditions for breeding sites (Leonard et al., 1993).

Size/Weight and Lifespan

Lithobates pipiens is a medium-sized (5 to 10 cm long snout-vent length [svl]) frog and their tadpoles are ~2.5 cm svl, and the females larger than the males (Leonard et al., 1993). In terms of size, Lithobates pipiens are said to be similar to a teacup (National Geographic Society, n.d.). Their average lifespan in the wild is two to four years; in captivity, it has been shown that Lithbates pipiens is able to love for 9 years (Crowley, n.d.).

Diet

Lithobates pipiens are carnivores, and their diet consists of mainly small prey, such as insects, arachnids, worms and crustaceans (McAllister et al., 1999). In some cases, Lithovates pipiens will sit and wait, and may eat small birds, garter snakes and their own species (National Geographic Society, n.d.). Tadpoles are herbivores and forage for phytoplankton, algae, etc. (Ohanjanian & Paige, 2004).

Reproduction and Communication

Lithobates pipiens reach sexual maturity after approximately two years, but can range anywhere from one to three years (Ohanhanian & Paige, 2004). Breeding season and courtships being in mid-April and may last until June; males congregate in shallow water near breeding sites during this time (Ohanhanian & Paige, 2004). Males attract females through their call: a croak, which can sound like a snore followed by grunting noises or someone rubbing a balloon together (“Northern Leopard Frog [Rana pipiens]”, 2013).

In addition to the mating call, latitude and elevation will influence the timing of when females decide to deposit their eggs, but when they do, they deposit a single egg mass (consisting of 600 to 7000 eggs) and close in proximity to other egg deposits already present (Ohanhanian & Paige, 2004). This behavioural preference allows for there to be several eggs deposits in a small area (Ohanhanian & Paige, 2004).

Predation

Non-native predatory fish, such as bullheads, sunfish and bass, poses a risk to Lithobates pipens as they prey on these frogs and their tadpoles, enabling for a quick decline of population on the Pacific Coast (Hayes and Jennings, 1986). Other native species such as snakes, turtles, raccoons and other natural predators also prey on Lithobates pipiens (“Northern Leopard Frog [Rana pipiens]”, 2013).

Conservation Status

In western North America (consisting of the United States and Canada primarily), Lithobates pipens is considered to be a sensitive and threatened species, with the occasional sightings of small and rare populations being the only populations exhibited in those areas (Germaine & Hays, 2009). Conservation issues may also stem from other non-animals environmental factors such as disease, increased urbanization and the increased habitat fragmentation associated with the process, aquatic contaminants and pollutants, and other environmental factors (Germaine & Hays, 2009).

Did You Know?

The northern leopard frog utilizes its eyes to help assist with digestion! During the process of swallowing, muscles associated with the eye retract into the oropharynx, which comes into contact with the prey (Levine, Monroy & Brainerd, 2004). This is said to help push prey towards the esophagus or provide assistance for tongue-based transport (Levine, Monroy & Brainerd, 2004).

Scientific and Common Name:
The common name suggested and confirmed by the INaturalist community is the Northern Leopard Frog. This name is associated with the nomenclature genus species: Lithobates pipiens.

Habitat and Geographic Range:
The habitat of L. pipiens makes it so that it is common in its’ geographic range, which is a steady distribution between Hudson’s Bay, Canada to southern United States, to Kentucky and New Mexico (Germaine and Hays 2008). This meaning that the habitat is forested areas, grasslands and places where there is a permanent water supply, i.e. streams, riverbeds, surroundings of lakes (Germaine and Hays 2008). As seen in the picture I captured, inhabiting the surrounding to the lake of a conservation area.

Size/Weight and Lifespan:
The typical size (mass) of L. pipiens is anywhere between 20 - 30 grams, with a length of 2 - 4 inches from the snout to hind (Frost et al. 2009), therefore not counting the length from head to bottom of hindlegs. Females tend to be larger than males, and are less vibrant in their colouring (Trudeau et al. 2013). The average lifespan of a healthy leopard frog is approximately 9 years, along with reaching fertility at 1 year, for males, and 2 years for females (Germaine and Hays 2008).

Diet:
The diet of L. pipiens can be characterized as an opportunistic feeder, where it feeds on a wide range of available food (Bolek and Coggins 2003). It feeds on a range of insects, from beetles and ants to slugs and other smaller frogs. The tadpoles of L. pipiens feed on algae and decomposing vegetation (Bolek and Coggins 2003).

Reproduction and Communication:
Reproduction of L. pipiens is peculiar, as the males will collect in shallow breeding pools and will emit low frequency calls to attract mates (Trudeau et al. 2013), this is an example of intrasexual selection as in the males are showing their fitness by producing low frequency noises. This is form of communication between the sexes, but will also produce vocalizations at higher pitches out of the breeding season (Trudeau et al. 2013).

Predation:
L. pipiens does not have any species-specific predators, but are subject to be predated on by snakes and other larger frogs, like bullfrogs, and even raccoons and humans (Hammerson et al. 2004). They have very little in terms of defense mechanisms, instead relying on camouflage and agility to avoid predation (Bolek and Coggins 2003).

Conservation Status:
The conservation status of L. pipiens, as stated by the ICUN Red List of Threatened Species, is least concerned. However, with increasing global climate change, their habitats are being threatened, leading to their current population trend to be decreasing (Hammerson et al. 2004).

Fun Fact!
Did you know? Lithobates pipiens females can lay up to 5000 eggs during mating season, which is actually on the low side of other frog species, which can be up to 20,000 eggs (Trudeau et al. 2013).