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What the sources say

Wood FrogLithobates sylvaticus

Every figure, record and mechanism on the Wood Frog profile was written from a source, and this is the working table behind it: 41 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Animal Diversity Web, University of Michigan

Lithobates sylvaticus (wood frog). Animal Diversity Web, University of Michigan.

The page saysAs much as 35 to 45 percent of its body turns to ice beneath the skin
The source saysas much as 35 to 45% of a frog's body may freeze and turn to ice. Ice crystals form beneath the skin
The page saysits breathing, blood flow, and heartbeat stop
The source saysDuring the freeze the frog's breathing, blood flow, and heart beat cease.
The page saysThat sugar, combined with specialized proteins, keeps the water inside each cell from crystallizing while ice fills the spaces outside it
The source saysFreezing is made possible by specialized proteins and glucose, which prevent intracellular freezing and dehydration.
The page saysWood frogs live in tundra, bogs, and coniferous or deciduous forest
The source saysWood frogs inhabit a wide variety of habitats including tundra, thickets, wet meadows, bogs, coniferous and deciduous forests.
The page saysfound from northern Georgia to Alaska
The source saysThey are found from northern Georgia and in isolated colonies in the central highlands in the eastern to central parts of Alabama, up through the northeastern United States, and all the way across Canada into Alaska.
The page saysThey are found farther north than any other reptile or amphibian in North America
The source saysThey are found farther north than any other North American reptile or amphibian.
The page saysaverage about 8 grams
The source saysAverage mass 7.88 gNote: ADW displays this figure sourced from the AnAge database on its own page; rounded from 7.88 g.
The page saysA black patch runs from each wood frog's eardrum to the base of the front leg, earning the species the nickname "robber's mask,"
The source saysthey can be distinguished by a black patch that extends over the tympanum to the base of the front limb. It is this characteristic that causes them to be referred to as the frog with the "robber's mask".
The page saysagainst skin that's usually rust-brown or tan, but sometimes green or gray
The source saysThis species exhibits a number of color morphs, usually browns, tans and rust, but can also be found in shades of green and gray.
The page saysAdults eat small invertebrates, especially spiders, beetles, moth caterpillars, slugs, and snails
The source saysAdult wood frogs eat a variety of terrestrial insects and other small invertebrates, especially spiders (Order Araneae), beetles (Order Coleoptera), moth larvae (Order lepidoptera), slugs (Order Stylommatophora) and snails (Order Stylommatophora).
The page saysWood frogs are the first frogs of the year to start calling, often before the ice is completely off their breeding ponds
The source saysThey are the first frogs to begin calling, often before the ice is completely off the breeding ponds.
The page saysfilling the air with a chorus of duck-like quacking some describe as "a lot of chuckling"
The source saysthey create a chorus of duck-like quacking sounds, described by some as a "lot of chuckling".
The page saysEach female lays a globular mass of 1,000 to 3,000 eggs, 10 to 13 centimeters across
The source saysthe female will lay a globular egg mass ... Each egg mass measures about 10 to 13 cm in diameter, and can contain from 1000 to 3000 eggs.
The page saysNumerous small green algae then turn the jelly around the eggs green, which makes a great camouflage
The source saysThe jelly around the eggs becomes green in color creating a great camouflage. The green color of the jelly is due to the presence of numerous small green algae.
The page saysWood frog tadpoles have the strongest kin recognition yet discovered in amphibian larvae
The source saysWood frog tadpoles have been shown to have the strongest powers of kin recognition yet discovered in amphibian larvae.
The page saysResearchers marked tadpoles with dye and released them into natural habitats, and siblings sought each other out and regrouped together
The source saysThey have been documented (by marking them with dye and releasing them into natural habitats) to aggregate back together.
The page sayswhich may help them find food, keep warm, and avoid predators
The source saysThis may be a survival mechanism allowing them the potential benefit of food, thermoregulation, and defense against predators.
The page saysAdult wood frogs produce noxious skin secretions, though these only seem to deter shrews
The source saysAdult wood frogs have noxious skin secretions but they are only effective in deterring shrews.
The page saysthe frog may let out a piercing cry that startles its attacker into loosening its grip
The source saysIf captured, wood frogs may emit a piercing cry that may startle the attacker enough to release the frog.
The page saysA frog that can let ice fill over a third of its body each winter, stop its own heart, and thaw out alive again each spring
The source saysas much as 35 to 45% of a frog's body may freeze and turn to iceNote: Tagline; restates the freeze-percentage and heart-stop claims made in the body (35-45% rounds to "over a third").
The page saysTundra, bogs, and coniferous or deciduous forest
The source saysWood frogs inhabit a wide variety of habitats including tundra, thickets, wet meadows, bogs, coniferous and deciduous forests.Note: stats.habitat, first clause.
The page saysfarther north than any other North American reptile or amphibian
The source saysThey are found farther north than any other North American reptile or amphibian.Note: stats.habitat, second clause.
The page saysFirst to Call, Camouflaged as Eggs
The source saysThey are the first frogs to begin calling, often before the ice is completely off the breeding ponds.Note: Heading; 'camouflaged as eggs' refers to the green egg-mass jelly claimed later in the section.
The page saysIn winter, the wood frog (*Lithobates sylvaticus*) freezes while it hibernates
The source saysWood frogs utilize a cryogenic freezing process during hibernation. In the winter,
The page saysWhile a wood frog is frozen, its breathing, blood flow and heartbeat all stop.
The source saysDuring the freeze the frog's breathing, blood flow, and heart beat cease.

Source
02

National Wildlife Federation

Wood Frog. National Wildlife Federation.

The page saysIce forming inside its cells would be deadly
The source saysTheir bodies produce a special antifreeze substance that prevents ice from freezing within their cells, which would be deadly.
The page saysreaching north of the Arctic Circle
The source saysWood frogs are the only frogs that live north of the Arctic Circle.Note: Only the range fact is used. NWF's 'only frogs' superlative is cut: common and moor frogs also range north of the Arctic Circle in Eurasia.
The page saysAdults run 3.8 to 8.2 centimeters long
The source saysAdults of this amphibian species are 1.5 to 3.25 inches (3.8 to 8.2 centimeters) in length.
The page saysusually live no more than three years in the wild
The source saysA wood frog's lifespan in the wild is usually no more than three years.
The page saysIce forms in the spaces between the frog's cells, not inside them, where it would be deadly
The source saysprevents ice from freezing within their cells, which would be deadly. Ice does form, however, in the spaces between the cells.

Source
03

Larson et al. 2014

Larson et al. (2014). Wood frog adaptations to overwintering in Alaska: New limits to freezing tolerance. Journal of Experimental Biology.

The page saysWood frogs in Interior Alaska survive freezing to more extreme limits and durations than the populations studied in southern Canada and the Midwestern United States
The source saysWood frogs in Interior Alaska survive freezing to extreme limits and durations compared with those described in animals collected in southern Canada or the Midwestern United States.
The page saysTracked into their natural hibernacula, they stayed frozen for 193 days on average
The source saystracking animals into natural hibernacula ... Wood frogs in natural hibernacula remained frozen for 193 ± 11 consecutive days
The page saysthrough average minimum temperatures of -14.6°C and as low as -18.1°C, and all 18 of the frogs tracked survived the winter
The source saysaverage minimum temperatures of -14.6 ± 2.8°C (range -8.9 to -18.1°C) with 100% survival (N=18)
The page saysTheir muscles held glucose levels 13 times higher, and their hearts 10 times higher, than frogs frozen in a laboratory
The source saysMean glucose concentrations were 13-fold higher in muscle, 10-fold higher in heart and 3.3-fold higher in liver in naturally freezing compared with laboratory frozen frogs.
The page saysResearchers think that extra glucose builds up through the repeated freezing and thawing these frogs go through in early autumn
The source saysWe hypothesize that this enhancement of freeze tolerance in Alaskan wood frogs is due to higher cryoprotectant levels that are produced by repeated freezing and thawing cycles experienced under natural conditions during early autumn.
The page saysSix Months Frozen in Interior Alaska
The source saysremained frozen for 193 ± 11 consecutive daysNote: Heading rounds 193 days to roughly six months.

Source
04

Storey 1997

Storey (1997). Organic Solutes in Freezing Tolerance. Comparative Biochemistry and Physiology Part A: Physiology.

The page sayswhen ice starts forming in its outer tissues, the frog's liver rapidly manufactures large amounts of glucose and distributes it through the body
The source saysfreeze-tolerant frogs respond to ice formation in peripheral tissues by synthesizing large amounts of glucose in the liver and rapidly distributing the sugar throughout the body
The page saysWhen a frozen wood frog starts to warm up, its liver and heart melt before the rest of its body, letting its vital functions restart while the rest of the frog is still thawing
The source saysduring thawing, organs such as liver and heart melted first, allowing recovery of their vital functions to begin while the rest of the frog thawed
The page saysFreeze-tolerant animals like the wood frog build up high levels of small dissolved solutes, such as sugars, which limit how much of the body's water turns to extracellular ice and how much each cell shrinks as water leaves it
The source saysThe accumulation of high levels of low-molecular-weight solutes (polyhydric alcohols, saccharides) provides cryoprotection to freeze-tolerant animals by minimizing, via colligative effects, the percentage of body water converted to extracellular ice and the extent of cell volume reduction.
The page saysLiver and Heart Thaw First
The source saysduring thawing, organs such as liver and heart melted first, allowing recovery of their vital functions to begin while the rest of the frog thawedNote: Blockquote lead-in, restating the claim below it.

Source
05

The IUCN Red List of Threatened Species 2022

Lithobates sylvaticus. The IUCN Red List of Threatened Species 2022: e.T58728A193382501.

The page saysLeast Concern
The source saysIUCN Red List category: Least Concern (LC).Note: Category read through GBIF's copy of the Red List, per the source pack; the claim cites the assessment DOI, not the GBIF API.

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.