Northern Red-legged Frog
Encyclopedia
The northern red-legged frog (Rana aurora) is a species
of amphibian
, whose range is the coastal region stretching from southwest British Columbia
to Northern California
, and is protected in British Columbia, Oregon
and California. As a member of the genus
Rana
, this species is considered a true frog
, with characteristic smooth skin and a narrow waist
. This frog
requires still waters for breeding, and is rarely found at any great distance from its breeding pond
s or marsh
es.
Northern red-legged frog adults may attain a length of 8 centimetres (3.1 in); they have a dark facial mask and a characteristic light stripe along the jaw
line. The northern red-legged frog has long, powerful legs well adapted to jumping. It is one of two amphibian species classified as red-legged frog
, the other species being the California red-legged frog
(Rana draytonii); however, the latter species is found primarily from Marin County southerly to Baja California
. These two genetically
distinct species are believed to intergrade in the counties of Marin and Sonoma. In some systems of taxonomy
, this species is classified as Rana aurora aurora.
, western Washington and southwestern British Columbia
, including Vancouver Island
. In California
, its range includes every coast
al county from Mendocino County northward. While it occurs primarily in the Northern California coastal mountain ranges, it is not found above an elevation of 1200 meters. It also occurs somewhat less commonly in the southern Cascade Range
. The species is thought to intergrade with Rana draytonii in Marin County and Sonoma County, California, but has been observed as far south as San Mateo County.
pools are essential for northern red-legged frog breeding habitat
; moreover, this species of frog is considered unusually highly oriented to its aquatic habitat
, with a clear preference for thickly vegetated
shoreline. Rana aurora requires cover, since it is subject to predation
by various fish
es, snake
s, bird
s, mammal
s and even certain other amphibians. When this frog senses danger, it will quickly plunge to depths of one meter or more to seek safety in the benthic zone of a pond. Adults leave the breeding pond soon after the breeding activity is concluded, and may migrate about one half kilometer to their summer locations, which are likely to be riparian zone
s. In the northern part of its range, adults may hibernate
. Juveniles are slower to leave the breeding ponds, but also tend to find cover in riparian areas, and may readily migrate about one half kilometer by summertime. Mature Rana aurora specimens prey upon terrestrial
insect
s, but will also take small snail
s and crustacean
s; moreover, they will consume worm
s, tadpole
s, small fish and even small frogs of other species. The tadpole
e are herbivorous
.
s and female
s begin to move to the breeding sites as early as October, and sometimes as late as January, depending on latitude
, cumulative rainfall for the season and average temperature
. Typically, stable minimum temperatures of 42 to 44 degrees Fahrenheit are required to induce breeding. Observations of adult migration are best made on moonlit nights with light rains. The male is thought to defend his territory
, once he is in the breeding pond area, using nocturnal displays. In fact, most activity is at night, especially enhanced by periods of light rain. The actual courtship
behavior
s commence in January in the California part of the range, and as late as March in northerly regions. In any case, the breeding season terminates in July at the very latest, and earlier in the drier locales.
Each female produces 200 to 1100 eggs per season, and attaches the egg cluster to submerged vegetation or rotting logs, characteristically seven to 15 centimeters below the pond surface. Egg
clusters are typically about 10 centimeters in diameter, and may disperse into an irregular form underwater. Eggs hatch in 39 to 45 days, and tadpole
s require approximately 80 days to attain metamorphosis
.
Oviposition
generally takes place in densely vegetated, shallow portions of wetlands with little current, and in unusual cases, egg masses have been observed in water up to 500 centimeters in depth. Breeding sites can be either permanent or temporary, with inundation usually necessary into June for successful metamorphosis
. The June date is based on Oregon conditions; in Northern California late May or early June witnesses metamorphosis. Breeding is initiated when water temperatures exceed about six degrees Celsius
(usually in January), but can be as late as March in the extreme northern part of the range.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
, whose range is the coastal region stretching from southwest British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
to Northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...
, and is protected in British Columbia, Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
and California. As a member of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Rana
Rana (genus)
Rana is a genus of frogs. Species include such archetypal pond frogs as the common frog of Europe, brown frogs, and the New and Old World true frogs, including the various species of leopard frogs and the American bullfrog. Members of this genus are found through much of Eurasia, North America,...
, this species is considered a true frog
True frog
The true frogs, family Ranidae, have the widest distribution of any frog family. They are abundant throughout most of the world, occurring on most continents except Antarctica...
, with characteristic smooth skin and a narrow waist
Waist
The waist is the part of the abdomen between the rib cage and hips. On proportionate people, the waist is the narrowest part of the torso....
. This frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
requires still waters for breeding, and is rarely found at any great distance from its breeding pond
Pond
A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens, water features and koi ponds; all designed for aesthetic ornamentation as landscape or architectural...
s or marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
es.
Northern red-legged frog adults may attain a length of 8 centimetres (3.1 in); they have a dark facial mask and a characteristic light stripe along the jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...
line. The northern red-legged frog has long, powerful legs well adapted to jumping. It is one of two amphibian species classified as red-legged frog
Red-legged Frog
The Red-legged Frog, a threatened native species in Oregon, is a common name for a particular kind of frog of the west coast of North America. The Red-legged Frog requires stream side, woodland environments for survival...
, the other species being the California red-legged frog
California Red-legged Frog
The California red-legged frog, Rana draytonii, is a moderate to large species of frog. It is known under the scientific name Rana draytonii, after being long included with the northern red-legged frog The California red-legged frog, Rana draytonii, is a moderate to large (4.4–14 cm) species...
(Rana draytonii); however, the latter species is found primarily from Marin County southerly to Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
. These two genetically
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
distinct species are believed to intergrade in the counties of Marin and Sonoma. In some systems of taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
, this species is classified as Rana aurora aurora.
Range
The northern red-legged frog is found in western OregonOregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
, western Washington and southwestern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, including Vancouver Island
Vancouver Island
Vancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...
. In California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, its range includes every coast
Coast
A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...
al county from Mendocino County northward. While it occurs primarily in the Northern California coastal mountain ranges, it is not found above an elevation of 1200 meters. It also occurs somewhat less commonly in the southern Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...
. The species is thought to intergrade with Rana draytonii in Marin County and Sonoma County, California, but has been observed as far south as San Mateo County.
Habitat
The still waters of ponds, marshes or streamStream
A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...
pools are essential for northern red-legged frog breeding habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
; moreover, this species of frog is considered unusually highly oriented to its aquatic habitat
Freshwater biology
Freshwater ecosystems are a subset of Earth's aquatic ecosystems. They include lakes and ponds, rivers, streams and springs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content...
, with a clear preference for thickly vegetated
Vegetation
Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...
shoreline. Rana aurora requires cover, since it is subject to predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
by various fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
es, snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s, bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s and even certain other amphibians. When this frog senses danger, it will quickly plunge to depths of one meter or more to seek safety in the benthic zone of a pond. Adults leave the breeding pond soon after the breeding activity is concluded, and may migrate about one half kilometer to their summer locations, which are likely to be riparian zone
Riparian zone
A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the fifteen terrestrial biomes of the earth. Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by...
s. In the northern part of its range, adults may hibernate
Hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...
. Juveniles are slower to leave the breeding ponds, but also tend to find cover in riparian areas, and may readily migrate about one half kilometer by summertime. Mature Rana aurora specimens prey upon terrestrial
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...
insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, but will also take small snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s; moreover, they will consume worm
Worm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...
s, tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
s, small fish and even small frogs of other species. The tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
e are herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
.
Breeding
MaleMale
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
s and female
Female
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...
s begin to move to the breeding sites as early as October, and sometimes as late as January, depending on latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
, cumulative rainfall for the season and average temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
. Typically, stable minimum temperatures of 42 to 44 degrees Fahrenheit are required to induce breeding. Observations of adult migration are best made on moonlit nights with light rains. The male is thought to defend his territory
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
, once he is in the breeding pond area, using nocturnal displays. In fact, most activity is at night, especially enhanced by periods of light rain. The actual courtship
Courtship
Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. In courtship, a couple get to know each other and decide if there will be an engagement or other such agreement...
behavior
Behavior
Behavior or behaviour refers to the actions and mannerisms made by organisms, systems, or artificial entities in conjunction with its environment, which includes the other systems or organisms around as well as the physical environment...
s commence in January in the California part of the range, and as late as March in northerly regions. In any case, the breeding season terminates in July at the very latest, and earlier in the drier locales.
Each female produces 200 to 1100 eggs per season, and attaches the egg cluster to submerged vegetation or rotting logs, characteristically seven to 15 centimeters below the pond surface. Egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
clusters are typically about 10 centimeters in diameter, and may disperse into an irregular form underwater. Eggs hatch in 39 to 45 days, and tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
s require approximately 80 days to attain metamorphosis
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...
.
Oviposition
Oviposition
Oviposition is the process of laying eggs by oviparous animals.Some arthropods, for example, lay their eggs with an organ called the ovipositor.Fish , amphibians, reptiles, birds and monetremata also lay eggs....
generally takes place in densely vegetated, shallow portions of wetlands with little current, and in unusual cases, egg masses have been observed in water up to 500 centimeters in depth. Breeding sites can be either permanent or temporary, with inundation usually necessary into June for successful metamorphosis
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...
. The June date is based on Oregon conditions; in Northern California late May or early June witnesses metamorphosis. Breeding is initiated when water temperatures exceed about six degrees Celsius
Celsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
(usually in January), but can be as late as March in the extreme northern part of the range.
Further reading
- Hillis, D.M. & Wilcox, T.P. (2005): Phylogeny of the New World true frogs (Rana). Mol. Phylogenet. Evol.Molecular Phylogenetics and EvolutionMolecular Phylogenetics and Evolution is a peer-reviewed scientific journal of evolutionary biology and phylogenetics. The journal is edited by D.E. Wildman.-Indexing:The journal is indexed in:*EMBiology*Journal Citation Reports*Scopus*Web of Science...
34(2): 299–314. PDF fulltext. - Hillis, D. M. (2007) Constraints in naming parts of the Tree of Life. Mol. Phylogenet. Evol.Molecular Phylogenetics and EvolutionMolecular Phylogenetics and Evolution is a peer-reviewed scientific journal of evolutionary biology and phylogenetics. The journal is edited by D.E. Wildman.-Indexing:The journal is indexed in:*EMBiology*Journal Citation Reports*Scopus*Web of Science...
42: 331–338.