9 Types of Frogs Found in Maine (ID Guide with Pictures and Sounds)

Maine’s forests, wetlands, and vernal pools echo with amphibian calls that mark the changing seasons as reliably as any calendar. While you might expect dozens of species in such diverse habitats, only nine types of frogs in Maine have established populations—a surprisingly modest number for a state with such abundant freshwater resources.

Each species has evolved unique adaptations to survive Maine’s harsh winters and capitalize on brief northern breeding seasons, from the tiny spring peeper’s high-pitched chorus that signals spring’s arrival to the deep-voiced bullfrog’s summer serenade.

Understanding these nine amphibians transforms casual nature walks into opportunities to identify species by sight, sound, and habitat preference.

American Bullfrog

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The American bullfrog (Lithobates catesbeianus) commands attention as Maine’s largest frog species, with some individuals reaching dinner-plate proportions. You’ll recognize their distinctive deep “jug-o-rum” call resonating across lakes and large ponds during summer evenings—a sound that carries for over a mile under ideal conditions.

These impressive amphibians measure 3.5-8 inches from snout to vent, with females typically outgrowing males. Their robust build, olive-green to brown coloration, and prominent tympanum (eardrum) distinguish them from other Maine frogs. Males display bright yellow throats during breeding season, while females have white or cream-colored throats.

Habitat and Behavior

Bullfrogs thrive in permanent water bodies with abundant vegetation and muddy bottoms. You’ll find them in:

• Large ponds and lakes with cattail margins
• Slow-moving rivers and streams
• Beaver ponds with established aquatic plant communities
• Farm ponds and reservoirs

Key Insight: Bullfrogs have the longest tadpole stage of any Maine amphibian—larval development takes 1-3 years depending on water temperature. You can find bullfrog tadpoles overwintering beneath ice, growing substantially before metamorphosis.

Unlike most Maine amphibians that breed in early spring, bullfrogs wait for warmer water temperatures. Their breeding season extends from late May through July, with males establishing territories and calling from emergent vegetation. The deep, resonant call serves both to attract females and warn competing males away from prime breeding sites.

Identification Tips

When identifying bullfrogs, look for these distinctive features:

• Absence of dorsolateral ridges (raised folds running down the back)
• Very large tympanum, especially in males where it exceeds eye diameter
• Fully webbed hind feet with no webbing gaps between toes
• Plain coloration without distinct spots or patterns
• Size—if it’s unusually large, it’s likely a bullfrog

Bullfrogs are voracious predators consuming insects, crayfish, small fish, other frogs, and occasionally small snakes or birds. Their appetite and competitive nature have made them problematic invasive species in some regions, though they’re native to southern Maine and have expanded their range northward as temperatures warm.

Green Frog

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You’ll encounter green frogs (Lithobates clamitans) more frequently than any other aquatic frog in Maine. Their explosive “gunk!” call—reminiscent of plucking a loose banjo string—punctuates summer days around virtually any permanent water body.

This common species bridges the gap between Maine amphibians and truly aquatic frogs, spending considerable time both in water and along shorelines.

Green frogs measure 2-4 inches in length, making them noticeably smaller than bullfrogs but larger than most terrestrial Maine frogs. Their coloration varies dramatically from bright green to bronze or brown, with some individuals displaying vibrant emerald heads that fade to brown on the back and legs.

Distinctive Features

The most reliable identification feature for green frogs is the presence of dorsolateral ridges—raised skin folds that run from behind the eye about two-thirds down the back before curving toward the groin. You won’t find these ridges on bullfrogs, making this the quickest way to distinguish the species.

Males develop bright yellow throats during breeding season and possess larger tympanums than females. The tympanum in male green frogs exceeds eye diameter, while female tympanums roughly match eye size—a useful characteristic when trying to sex individuals you encounter.

Pro Tip: Green frog calls vary in pitch and tone even within the same population. Some males produce higher-pitched “gunk!” sounds while others deliver deeper, more resonant calls. This variation helps you distinguish multiple calling males at a single breeding site.

Habitat Preferences

Green frogs inhabit a wider range of water bodies than bullfrogs, tolerating smaller ponds and cooler temperatures. You’ll find them in:

• Streams and brooks with pools
• Small to large ponds
• Lake margins with vegetation
• Marshy areas and swamps
• Even temporary pools that retain water through summer

These adaptable amphibians breed throughout late spring and summer, with males calling from May into August in Maine. Unlike explosive breeders that gather for brief, intense breeding events, green frogs maintain territories over extended periods, defending prime calling sites from competitors.

Green frogs overwinter in the mud at pond bottoms, occasionally sharing hibernation sites with bullfrogs and other aquatic species. Their ability to tolerate various habitat conditions and their extended breeding season contribute to their status as one of Maine’s most abundant and successful frog species.

Pickerel Frog

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The pickerel frog (Lithobates palustris) stands apart from other types of frogs in Maine through its geometric perfection—neat rows of square or rectangular spots arranged in parallel lines down the back.

You’ll recognize this medium-sized species by its mathematical precision, but handle it carefully: pickerel frogs produce skin secretions toxic enough to kill other amphibians sharing the same container.

These distinctive frogs measure 1.75-3.5 inches in length, with females growing larger than males. Their base coloration ranges from tan to light brown, providing an ideal canvas for the dark chocolate-brown spots that define the species.

The pattern remains consistent—two parallel rows of spots between prominent dorsolateral ridges—making identification straightforward even from a distance.

Warning Coloration and Defense

Flip a pickerel frog over, and you’ll discover another identification feature: bright yellow or orange coloration on the undersides of the hind legs and lower belly. This flash coloration serves as a warning to predators about the frog’s toxic skin secretions.

The skin toxins (primarily peptides and alkaloids) won’t harm you through casual handling, but they’re potent enough to kill smaller amphibians.

This chemical defense system explains why you should never transport pickerel frogs in containers with other amphibian species—the secretions can prove fatal to tank mates within hours.

Important Note: Despite their toxic defenses, pickerel frogs face predation from snakes (particularly garter snakes), birds, and larger frogs that have evolved resistance to the toxins. The warning coloration doesn’t guarantee survival, but it reduces predation pressure.

Habitat and Breeding Behavior

Pickerel frogs show strong preferences for cool, clear water with neutral to slightly alkaline pH. You’ll encounter them in:

• Clear, cold streams and brooks
• Spring-fed pools and seepage areas
• Sphagnum bogs and fens
• Pond margins with emergent vegetation
• Wet meadows adjacent to permanent water

Unlike green frogs and bullfrogs that remain near water year-round, pickerel frogs often wander considerable distances from breeding sites during summer. You might spot them in forests, fields, or under logs far from visible water—they’re more terrestrial than their spotted pattern suggests.

Breeding occurs from late April through May in Maine, with males producing a steady, low-pitched snore lasting 1-2 seconds. The call lacks the explosive quality of green frog vocalizations or the musical nature of spring peeper calls—it’s more of a sustained, grating croak.

Males call while floating in shallow water, often choosing breeding sites in temporary pools, ditches, or flooded areas where predator pressure is reduced.

Pickerel frogs deposit egg masses attached to submerged vegetation in relatively deep water (6-12 inches), distinguishing their breeding strategy from wood frogs that lay eggs in very shallow water.

The species faces declining populations in portions of its range due to habitat loss, water pollution, and sensitivity to environmental changes—making protection of cool, clean water sources crucial for their survival.

Northern Leopard Frog

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You’ll recognize the northern leopard frog (Lithobates pipiens) by its stunning spotted pattern—large, dark spots with light borders scattered across a green or brown background like perfectly placed wildlife artwork.

This medium-sized species once thrived throughout Maine but has experienced concerning population declines, making every encounter with these beautiful amphibians increasingly noteworthy.

Northern leopard frogs measure 2-4.5 inches in length, with a sleek, athletic build adapted for impressive jumping ability.

Their spots are larger and more irregularly arranged than pickerel frog spots, lacking the geometric precision of parallel rows. You’ll also notice prominent, light-colored dorsolateral ridges running from behind the eyes to the groin—these ridges are lighter and more pronounced than in many other Maine frogs.

Distinguishing Features and Calls

Several characteristics help you distinguish northern leopard frogs from similar species:

• Light-colored spot on the tympanum (eardrum)
• White line along the upper jaw
• Inset snout creating a more pointed face profile
• Scattered spot pattern rather than organized rows
• Bright green or brown base color (not the tan of pickerel frogs)

The breeding call combines a long, rattling snore with periodic guttural croaks—often described as a “snoring” sound followed by clucking notes.

Males call both underwater and from the surface, creating a chorus that sounds mechanical and rhythmic. You might also hear a sharp “screaming” call when the frog is startled or captured—a distress vocalization that can surprise unsuspecting handlers.

Pro Tip: Northern leopard frogs are exceptional jumpers, capable of leaping 3-5 feet in a single bound—roughly 10-20 times their body length. When you approach one, expect it to cover remarkable distance with just a few jumps. This athletic ability explains their historical use in biology lab jumping experiments.

Habitat and Conservation Concerns

Northern leopard frogs utilize a broader range of habitats than most Maine amphibians, though they show preferences for open, grassy areas near water. You’ll find them in:

• Wet meadows and marshes
• Lake and pond margins with grassy vegetation
• Beaver flowages and flooded fields
• Stream corridors with adjacent grasslands
• Agricultural areas with irrigation ditches

Unlike many Maine frogs that remain near breeding sites, leopard frogs are highly mobile. They commonly travel 0.5-1 mile from water during summer, feeding in fields and grasslands before returning to wetlands for breeding and overwintering.

The species faces significant conservation challenges across its range. Population declines in Maine and throughout the Northeast stem from multiple factors including habitat loss, pesticide exposure, disease, and possibly climate change effects on breeding timing. Some historical breeding sites in southern Maine no longer support populations, raising concerns about the species’ long-term viability.

Breeding occurs from late April through early June, with males arriving first to establish calling sites in shallow water. Females deposit large egg masses (3,000-6,500 eggs) attached to submerged vegetation.

Unlike wood frog eggs laid in conspicuous communal masses, leopard frog eggs are deposited individually or in small groups, making them harder to locate.

Wood Frog

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When you hear the first duck-like quacking emanating from vernal pools in late March or early April, you’re witnessing one of Maine’s most remarkable natural phenomena: wood frog (Lithobates sylvaticus) breeding aggregations.

This terrestrial species possesses the most extreme cold tolerance of any North American amphibian, surviving winter temperatures that would kill other frogs through a fascinating physiological process called cryoprotection.

Wood frogs measure 1.4-3.25 inches in length, with a robust build and coloration ranging from light tan to dark brown or reddish-brown.

The defining identification feature is an unmistakable dark mask—a chocolate-brown or black patch extending from the snout through the eye to the tympanum, giving wood frogs a distinctive “bandit” appearance.

Freeze Tolerance and Winter Survival

Wood frogs survive Maine winters through one of nature’s most remarkable adaptations. Rather than hibernating in deep water or underground below the frost line, they overwinter beneath leaf litter and shallow soil. When temperatures drop below freezing, they actually freeze solid—up to 70% of their body water converts to ice.

How do they survive this frozen state? Their bodies produce high concentrations of glucose (essentially turning their blood into antifreeze) that protects vital organs while ice forms in body cavities.

This cryoprotection allows wood frogs to survive temperatures as low as -18°F (-8°C), resuming normal function once temperatures rise above freezing.

Key Insight: Wood frogs are typically the first Maine amphibians to breed each spring, sometimes calling and breeding while ice still covers portions of vernal pools. Their early breeding strategy allows tadpoles to develop and metamorphose before pools dry and before aquatic predators become active.

Breeding Behavior and Habitat

Wood frogs show strong preferences for vernal pools—temporary wetlands that fill with snowmelt and spring rains but dry by mid-to-late summer. These fishless environments provide critical advantages:

• Absence of predatory fish that would consume eggs and tadpoles
• Reduced competition from other amphibian species
• Abundant food resources (algae, detritus) for developing larvae
• Suitable developmental timing matching pool hydroperiod

Breeding occurs explosively over just 3-7 days, with entire populations converging on breeding pools simultaneously. Males produce a duck-like quacking call—shorter and more clucking than the melodious calls of spring peepers. The chorus can be heard from considerable distances, signaling the arrival of spring in Maine woodlands.

You’ll find wood frog egg masses as conspicuous communal clusters in shallow water (2-6 inches deep), often with dozens of egg masses deposited together.

Each mass contains 500-3,000 eggs and appears as a softball-sized gelatinous sphere attached to twigs or vegetation. The communal deposition creates a thermal advantage—clustered masses can be several degrees warmer than surrounding water, accelerating development.

Year-Round Ecology

Despite their dramatic spring breeding aggregations, wood frogs spend most of the year in upland forests far from water. You’ll encounter them during summer in:

• Mixed and deciduous forests with substantial leaf litter
• Forest edges and clearings
• Under logs, rocks, and bark
• Occasionally in suburban areas with nearby woodlands

They feed on a variety of invertebrates including beetles, spiders, slugs, and various insects. Their terrestrial lifestyle and freeze tolerance make wood frogs among Maine’s most successful amphibians, found from southern coastal areas to northern Aroostook County and from lowland valleys to mountain forests up to treeline.

Spring Peeper

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The spring peeper (Pseudacris crucifer) produces one of the most recognizable and beloved sounds in Maine—a high-pitched, ascending whistle that transforms March and April nights into symphony performances.

These tiny amphibians rarely exceed an inch in length, yet their calls can reach 90 decibels from just 50 feet away, roughly equivalent to standing near a lawnmower.

Spring peepers measure just 0.75-1.5 inches, making them among Maine’s smallest frogs. Their tan, brown, or gray coloration provides excellent camouflage against leaf litter and bark, but look closely and you’ll notice their defining feature: a dark X-shaped mark on the back.

This cross pattern (Latin: crucifer means “cross-bearing”) varies in clarity from individual to individual—some display bold, obvious crosses while others show faint or incomplete markings.

Calling Behavior and Acoustics

Male spring peepers produce their characteristic “peep” call by inflating a large vocal sac that expands to nearly the size of the frog’s body. The call serves multiple functions:

• Attracting females: Higher-pitched calls at faster rates indicate more desirable males
• Territory establishment: Males space themselves acoustically to avoid interference
• Temperature indication: Call rate increases with temperature, reaching peak rates at 60-70°F

Individual males may deliver 4,000+ calls per night during peak breeding season, though they don’t call every night—they take rest periods between calling bouts. You’ll notice the chorus begins around sunset and peaks between 8 PM and midnight, with reduced activity toward dawn.

Pro Tip: Spring peeper choruses operate on an alternation principle—nearby males time their calls to avoid overlapping, creating a coordinated rhythm. When one male calls, neighbors briefly pause before resuming, producing the pulsing quality characteristic of large choruses.

Habitat and Breeding Strategy

Spring peepers breed in a variety of temporary and permanent wetlands across Maine, showing less specialization than wood frogs. You’ll find them calling from:

• Vernal pools and ephemeral wetlands
• Forested swamps and wooded wetlands
• Marsh edges and cattail stands
• Flooded fields and ditches
• Even roadside puddles and temporary pools

Males call from vegetation 1-3 feet above water, grasping grass stems, shrub branches, or emergent vegetation. Unlike wood frogs that breed explosively over a few days, spring peeper breeding extends for 2-3 weeks or longer, with peaks following warm rains.

Females deposit 800-1,000 eggs singly or in small clusters attached to submerged vegetation or debris. The eggs are tiny (1-1.5 mm diameter) and nearly transparent, making them difficult to locate. Tadpoles develop rapidly, metamorphosing within 6-12 weeks depending on water temperature.

Year-Round Ecology

Despite their aquatic breeding habits, spring peepers are highly arboreal—spending much of the year in trees and shrubs. Their enlarged toe pads (characteristic of treefrogs) allow them to climb vertical surfaces and cling to vegetation. You might encounter them several feet off the ground during summer months, hunting small insects on tree bark and leaves.

During winter, spring peepers hibernate in crevices, under bark, and in leaf litter, surviving through partial freeze tolerance similar to wood frogs (though less extreme). They can tolerate brief periods of freezing but cannot survive the prolonged frozen conditions that wood frogs endure.

Their small size makes spring peepers vulnerable to desiccation, so they remain in humid microhabitats during dry periods. Despite this vulnerability, they’re among Maine’s most abundant and widespread amphibians, found in every county and in virtually every habitat type with suitable breeding sites.

Gray Treefrog

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Maine’s gray treefrogs present an identification puzzle that requires more than visual observation to solve. Two nearly identical species—the gray treefrog (Hyla versicolor) and Cope’s gray treefrog (Hyla chrysoscelis)—look so similar that you cannot reliably distinguish them by appearance alone. The key difference? Their calls, which reflect a fundamental genetic distinction between these cryptic species.

Both species measure 1.25-2.5 inches in length, making them Maine’s largest treefrogs. You’ll recognize them by their warty skin texture (unusual for treefrogs), large toe pads adapted for climbing, and remarkable color-changing ability. Gray treefrogs can shift from nearly white to dark gray or green, matching their background within 5-10 minutes.

Identification Challenges and Solutions

Visual characteristics shared by both species include:

• Mottled gray, brown, or green coloration with irregular blotching
• Bright yellow or orange flash coloration on inner thighs (hidden until the frog jumps)
• White spot beneath each eye
• Warty skin texture resembling tree bark
• Large toe pads with sticky mucus for climbing

Key Insight: The two species represent a fascinating case of polyploid speciation. Gray treefrogs are tetraploid (containing four sets of chromosomes rather than the normal two), likely arising through chromosome duplication in ancestral Cope’s gray treefrog populations. Despite looking identical, they cannot interbreed due to genetic incompatibility.

Call Characteristics and Breeding

The most reliable way to distinguish these species is through their breeding calls:

• Gray treefrog: Produces a slower, more melodious trill resembling a musical trill or short birdlike song. The sound is often described as “sweeter” and more musical. Each pulse is longer and more distinct.
• Cope’s gray treefrog: Delivers a faster, buzzier trill that sounds harsher and more insect-like. The rapid pulse rate creates a machine-gun quality lacking the musical character of gray treefrog calls.

Both species call from trees and shrubs near breeding sites rather than from water or ground level. Males position themselves 3-20 feet above ground in vegetation, producing calls that can be heard up to 0.5 miles away on calm nights.

Breeding occurs from late May through July in Maine, with activity peaks following warm rains. Unlike spring peepers that prefer wetland vegetation, gray treefrogs select taller trees and shrubs as calling perches, descending to water only for amplexus and egg deposition.

Habitat and Behavior

Gray treefrogs inhabit wooded areas near permanent or semipermanent water bodies. You’ll find them in:

• Mixed and deciduous forests with ponds or swamps
• Wooded suburban areas with suitable breeding sites
• Forest edges near beaver ponds
• Wetland margins with tall trees and shrubs

During non-breeding periods, these arboreal amphibians spend most of their time in trees, often resting on bark where their camouflage makes them nearly invisible. Their toe pads secrete sticky mucus allowing them to climb smooth vertical surfaces and even rest upside-down on leaves.

Females deposit small packets of 10-40 eggs attached to submerged vegetation or floating on the water surface. Total clutch sizes range from 1,000-2,000 eggs deposited over several days. The eggs and tadpoles are highly vulnerable to predation, but rapid larval development (6-8 weeks to metamorphosis) improves survival rates.

Gray treefrogs overwinter in tree cavities, under bark, and in rock crevices, surviving through freeze tolerance similar to wood frogs. The tetraploid gray treefrog shows slightly better cold tolerance than its diploid cousin, potentially explaining its wider distribution in northern Maine.

Cope’s Gray Treefrog

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Cope’s gray treefrog (Hyla chrysoscelis) shares nearly every physical characteristic with the gray treefrog, yet represents a completely distinct species—a prime example of cryptic species that eluded scientific recognition until the mid-20th century.

Named after the famous American herpetologist Edward Drinker Cope, this diploid species produces the faster, buzzier call that distinguishes it from its tetraploid relative.

The species exhibits identical size (1.25-2.5 inches), coloration patterns, and structural features to gray treefrogs. You’ll observe the same color-changing abilities, prominent toe pads, warty skin texture, and bright yellow-orange flash coloration on the inner thighs.

The white spot beneath the eye and mottled pattern provide camouflage against tree bark that’s so effective you might look directly at a Cope’s gray treefrog without recognizing it.

Genetic Distinction and Evolutionary History

The separation between these two species reflects evolutionary processes rather than geographical isolation:

1. Chromosome Count: Cope’s gray treefrog possesses the standard diploid chromosome count (24 chromosomes in 12 pairs). Gray treefrogs have 48 chromosomes in 24 pairs, arising through polyploidization.
2. Cell Size: Because tetraploid organisms have larger cell nuclei, gray treefrogs have slightly larger red blood cells and other cells—but this difference requires microscopic examination.
3. Reproductive Isolation: Despite overlapping ranges and similar breeding sites, the species cannot produce viable offspring. Any rare hybrids are infertile.

Pro Tip: When you encounter gray treefrogs in Maine, use a smartphone recording app to capture breeding calls. Later analysis of pulse rates (count pulses in one second of recording) can definitively identify the species—fewer than 35 pulses/second indicates gray treefrog, while more than 35 pulses/second indicates Cope’s gray treefrog.

Distribution in Maine

Cope’s gray treefrog reaches the northern limit of its range in Maine, occurring primarily in southern and central counties. The species shows preference for warmer habitats and may be limited by temperature constraints. You’re more likely to encounter Cope’s gray treefrog in:

• Southern coastal regions (York, Cumberland, Sagadahoc counties)
• Central Maine valleys (Kennebec, Androscoggin watersheds)
• Areas with milder microclimates and longer growing seasons

Gray treefrogs dominate in northern and inland Maine where cooler temperatures prevail. The two species overlap extensively in central Maine, sometimes calling from the same breeding sites—creating opportunities for direct comparison of their distinctive calls.

Breeding and Life History

Breeding biology closely parallels that of gray treefrogs, with males calling from elevated perches in trees and shrubs near water. The breeding season extends from late May through mid-July, with peak activity during warm, humid nights following rainfall.

Key breeding characteristics include:

• Males establish calling territories in trees 3-20 feet above ground
• Call rate correlates with temperature, increasing on warmer nights
• Females choose mates based on call characteristics and male size
• Egg deposition occurs in small packets scattered across breeding sites
• Tadpole development takes 6-8 weeks depending on water temperature

Research suggests that Cope’s gray treefrogs may show slightly earlier breeding phenology than gray treefrogs in areas of sympatry (overlapping ranges), potentially reducing competition for breeding sites and mates.

During non-breeding seasons, Cope’s gray treefrogs maintain arboreal lifestyles, feeding on flying insects, spiders, and other small invertebrates encountered in tree canopies. Their climbing ability and camouflage make them effective predators of moths, beetles, and other insects that rest on tree bark during daylight hours.

Like their tetraploid relatives, Cope’s gray treefrogs possess freeze tolerance for overwintering, though potentially at lower tolerance levels. This physiological limitation may contribute to their more southern distribution compared to gray treefrogs that extend farther into northern Maine’s harsher winter conditions.

Mink Frog

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You’ll encounter the mink frog (Lithobates septentrionalis) only in northern Maine, where it represents the state’s most specialized aquatic species.

Named for the distinctive odor it releases when handled—reminiscent of mink scent or rotting vegetation—this northern species reaches the southern limit of its range in Maine’s lakes and cold streams.

Mink frogs measure 1.9-3 inches in length, with a streamlined build adapted for aquatic life. Their coloration ranges from olive-green to dark brown, often with a bronze or golden sheen.

The defining visual features include irregular dark spots or mottling on the back and legs, combined with extensive webbing on the hind feet—more complete webbing than most other Maine frogs except bullfrogs.

Identification Features and Unique Characteristics

Several characteristics distinguish mink frogs from similar species:

• Prominent dorsolateral ridges similar to green frogs but less prominent
• Mottled or spotted pattern rather than geometric spots (unlike pickerel or leopard frogs)
• Strong odor when handled (the most reliable identification feature)
• Fully webbed hind feet with webbing reaching to or near the toe tips
• Preference for floating vegetation (especially water lilies)

The most distinctive feature remains the odor—a musky, onion-like or rotten-vegetable smell released from skin glands when the frog is handled or threatened. This defensive secretion is unique among types of frogs in Maine and provides instant identification confirmation, though you’ll need to handle the frog to detect it.

Important Note: Mink frogs are Maine’s most cold-adapted aquatic frogs, thriving in waters too cold for green frogs or bullfrogs. If you find an aquatic frog in a cold northern Maine lake or stream, especially one associated with water lilies, it’s likely a mink frog rather than other similar-looking species.

Habitat Specialization

Mink frogs show strong habitat preferences, limiting their distribution in Maine to suitable cold-water environments. You’ll find them exclusively in:

• Cold, clear lakes with water lily pads
• Lily-pad dominated ponds in northern regions
• Cool, rocky streams and brooks
• Beaver ponds in northern forests
• Lake margins with extensive aquatic vegetation

Unlike green frogs that utilize a broad range of water bodies, mink frogs require specific conditions: cool water temperatures, abundant floating vegetation (particularly lily pads), and well-oxygenated water. They’re rarely found in warm, weedy ponds or slow-moving waters that support green frog populations.

The species shows remarkable fidelity to water lily habitats, spending most of their lives sitting on lily pads or swimming between floating vegetation. This association likely reflects both the optimal calling platforms that lily pads provide and the abundant food resources (aquatic insects) associated with these plants.

Breeding Behavior and Calls

Mink frogs produce one of Maine’s most unusual breeding calls—a series of rapid, percussive “cut-cut-cut-cut” sounds often compared to hammering wood or cutting with a saw. Individual calls consist of 2-6 rapid notes delivered in quick succession, repeated at irregular intervals.

Breeding occurs relatively late compared to most Maine amphibians, from June through August. Males call from lily pads or emergent vegetation, usually within a few feet of shore in water 1-3 feet deep. The extended breeding season reflects the northern latitudes where mink frogs occur—shorter summers require more flexible breeding timing.

Females deposit eggs in surface films attached to submerged vegetation, typically in relatively deep water (2-4 feet) compared to most Maine frog species. Clutch sizes range from 500-4,000 eggs.

Tadpoles develop slowly in cold northern waters, often requiring two years to reach metamorphosis—an extended larval period similar to bullfrogs but in much colder environments.

Distribution and Conservation

In Maine, mink frogs occur primarily north of a line from Bangor to Rangeley, with populations concentrated in:

• Moosehead Lake region and surrounding waters
• Allagash Wilderness Waterway
• Aroostook County lakes and streams
• Cold-water habitats throughout northern Maine

The species becomes increasingly common as you travel north, reaching peak abundance in Maine’s northernmost counties. This distribution reflects temperature limitations—mink frogs struggle in warmer waters where green frogs and bullfrogs dominate.

Climate change poses potential threats to mink frog populations as warming water temperatures may favor more heat-tolerant competitors (especially green frogs) while degrading the cold-water conditions mink frogs require. Conservation of cold-water habitats in northern Maine becomes increasingly important for maintaining viable populations of this specialized species at the southern edge of its range.

Understanding Maine’s nine frog species transforms your experience of the state’s natural soundscape and wetland habitats.

From the earliest wood frog choruses signaling winter’s retreat to late-summer mink frog calls echoing across northern lakes, each species contributes unique adaptations to Maine’s amphibian community.

Whether you’re identifying frogs by their calls during breeding season, searching for tadpoles in vernal pools, or encountering adults during summer forest walks, you’re now equipped to recognize and appreciate the remarkable diversity of types of frogs in Maine—a modest but fascinating assemblage of amphibians shaped by northern climates, diverse habitats, and evolutionary pressures spanning millions of years.