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What the sources say

Great Crested GrebePodiceps cristatus

Every figure, record and mechanism on the Great Crested Grebe profile was written from a source, and this is the working table behind it: 51 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

Podiceps cristatus (great crested grebe). Animal Diversity Web, University of Michigan.

The page saysthe largest grebe in Europe
The source saysGreat crested grebes are the largest grebes in Europe.
The page saysrunning 46 to 61 cm long with a wingspan of 59 to 73 cm
The source saysRange length 46 to 61 cm ... Range wingspan 59 to 73 cm
The page sayswithin a range of 800 to 1,490 grams
The source saysRange mass 800 to 1490 g
The page saysIts legs are set far back for swimming and diving
The source sayslegs set far back for efficient swimming and diving
The page saysgrebes cannot travel across land
The source saysgrebes are aquatic specialists and cannot travel across land
The page saysIt finds prey by sight
The source saysThey detect prey in the water using visual cues.
The page sayseats mainly large fish, with roach, perch and smelt among its favored foods
The source saysThe diet of great crested grebes consists mainly of large fish ... Their favored foods include roach (Rutilus rutilus), perch (Perca fluviatilis), and smelt (Osmerus eperlanus).
The page saysit forages most at dawn and dusk, possibly because that is when its prey are closest to the surface
The source saysThey forage the most during dawn and dusk, possibly because this is when their prey are closest to the surface.
The page saysBreeding birds need shallow open fresh or brackish water, with vegetation on the banks and in the water for their nests
The source saysBreeding habitats consist of shallow open bodies of fresh or brackish water. There must also be vegetation on the banks and in the water in order to provide suitable locations for nests.
The page saysThe species lives year-round from Western Europe and Britain to parts of Africa, Australia and New Zealand, breeds east through southern Russia to Mongolia, and winters as far as southern Asia
The source saysGreat crested grebes are residents of Western Europe, Britain, and Ireland, parts of southern and eastern Africa, Australia, and New Zealand. Breeding populations are found from Eastern Europe through Southern Russia and to Mongolia. After migration, wintering populations can be found on the coastal waters of Europe, southern Africa, and Australia, as well as in bodies of water throughout southern Asia.
The page saysIn Victorian Britain its breast plumage and head plumes decorated clothing, which greatly threatened the species
The source saysTheir breast plumage and head plumes were also used for decoration on clothing during Victorian times in Britain. This, however, greatly threatened the species
The page saysCourtship begins with the male and female facing each other, necks held up straight and crests erected, both shaking their heads from side to side
The source saysIt begins with the male and female facing each other, necks held up straight, showing the whites of their necks. Their ears are vertical, the crest is erected, and the tail is cocked. They both shake their heads from side-to-side
The page saysNests are made of aquatic weeds and reeds woven into existing water plants
The source saysNests are made of aquatic weeds, reeds, thickets, and kelp fronds. These materials are woven into existing water plants.
The page saysThey are suspended in the water, which protects the clutch from terrestrial predators, and must be reachable from the water
The source saysThe nests are suspended in the water, which protects the clutch from terrestrial predators. ... Nests need to be accessible from water
The page saysClutches range from 1 to 9 eggs but average 3 to 4
The source saysClutches range from 1 to 9 eggs, but average between 3 and 4 eggs.
The page saysboth parents incubate equally for 27 to 29 days
The source saysIncubation lasts 27 to 29 days and both males and females incubate equally.
The page saysOnce the chicks leave the nest, the parents take turns carrying them on their backs for up to 3 weeks
The source saysOnce the chicks leave the nest, the parents take turns carrying young on their back out into the water for up to 3 weeks.
The page saysThe Animal Diversity Web account links that to avoiding juvenile predation, though it found no information in the literature about which predators take great crested grebe chicks or adults
The source saysThere is no information in the literature about specific predators of juvenile or adult great crested grebes. ... To avoid juvenile predation, adults carry chicks on their backs for up to 3 weeks after hatching.
The page saysThe predator it does name is the Eurasian coot, which eats eggs
The source saystheir main predators, Eurasian coots (Fulica atra), which prey on eggs
The page saysA parent covers the eggs with nest material before leaving, which has been found to protect them effectively against coots, and when the nest is disturbed it dives and resurfaces farther away
The source saysthey cover the eggs with nest material before leaving the nest. This behavior has been found to effectively protect against their main predators, Eurasian coots (Fulica atra), which prey on eggs. When the nest is disturbed, the parent covers the eggs, dives into the water, and resurfaces in a location farther away from the nest.
The page saysThe diving bird
The source saysGreat crested grebes are mainly diving birds and prefer to dive and swim rather than fly.
The page sayswhose courtship runs from paired head-shaking
The source saysIt begins with the male and female facing each other, necks held up straight ... They both shake their heads from side-to-side
The page sayswhose chicks ride on their parents' backs
The source saysthe parents take turns carrying young on their back out into the water for up to 3 weeks
The page saysLakes, artificial waters, slow rivers, swamps, bays and lagoons
The source saysGreat crested grebes can be found in a variety of aquatic habitats, including lakes, artificial bodies of water, slow flowing rivers, swamps, bays, and lagoons.
The page saysacross Europe, Asia, Africa, Australia and New Zealand
The source saysGreat crested grebes are residents of Western Europe, Britain, and Ireland, parts of southern and eastern Africa, Australia, and New Zealand. Breeding populations are found from Eastern Europe through Southern Russia and to Mongolia.
The page saysMainly fish such as roach, perch and smelt, plus insects, crustaceans, molluscs and amphibians
The source saysThe diet of great crested grebes consists mainly of large fish, but also includes insects, crustaceans, molluscs, adult and larval amphibians, and invertebrate larvae. Their favored foods include roach (Rutilus rutilus), perch (Perca fluviatilis), and smelt (Osmerus eperlanus).
The page saysGreat crested grebes eat their own feathers more often when their diet is low in indigestible matter
The source saysThey ingest their feathers more frequently when their diet is low in indigestible matter
The page saysThe Animal Diversity Web account says this is thought to be a way to make pellets the bird can eject, cutting down parasites in its gastric system
The source saysthis is thought to be a way to create pellets that can be ejected in order to decrease the occurrence of parasites in the gastric system
The page saysParents take turns carrying the young out onto the water on their backs for up to 3 weeks, and still guard them in the 4th week
The source saysthe parents take turns carrying young on their back out into the water for up to 3 weeks. The parents still guard the chicks in the 4th week.
The page saysThe Animal Diversity Web account gives avoiding juvenile predation as the reason, though it found no information in the literature about specific predators of great crested grebe chicks or adults
The source saysThere is no information in the literature about specific predators of juvenile or adult great crested grebes. ... To avoid juvenile predation, adults carry chicks on their backs for up to 3 weeks after hatching.
The page saysThe example it offers is another species: western grebe chicks are preyed on by fish such as bass and pike
The source saysHowever, chicks of another grebe species, western grebes (Aechmophorus occidentalis), are preyed on by fish such as bass species (Micropterus) and pike species (Esox).
The page saysfacing each other, both birds shake their heads from side to side
The source saysIt begins with the male and female facing each other, necks held up straight ... They both shake their heads from side-to-sideNote: vibe.reason, settled in #836.

Source
02

British Trust for Ornithology

Great Crested Grebe BirdFacts. British Trust for Ornithology.

The page saysThe British Trust for Ornithology gives its weight as 993 grams
The source saysWeight 993g Eggs 3-4
The page sayspersecution for its feathers once reduced England's population to as few as 32 known pairs
The source saysHistorically persecuted for its beautiful feathers, the Great Crested Grebe population was once reduced to as few as 32 known pairs in England.

Source
03

AnAge: The Animal Ageing and Longevity Database, Human Ageing Genomic Resources

AnAge entry for Podiceps cristatus. AnAge: The Animal Ageing and Longevity Database, Human Ageing Genomic Resources.

The page saysThat is a maximum recorded age, not a typical lifespan
The source saysMaximum longevity 19.2 years (wild)Note: labels the figure as AnAge does, a maximum from banding studies; AnAge gives no typical lifespan
The page saysthe record from banding studies is a wild bird of 19.2 years
The source saysMaximum longevity 19.2 years (wild) ... Maximum longevity from banding studies is 19.2 years [ 0450 ].Note: AnAge's source [0450] is Fransson et al. (2010), EURING list of longevity records for European birds. A maximum from ringing, labelled as a record, not a typical lifespan.
The page saysThe record from banding (ringing) studies is 19.2 years for a wild bird, a figure AnAge takes from the EURING list of longevity records for European birds
The source saysMaximum longevity 19.2 years (wild) ... Source ref. 450 ... Maximum longevity from banding studies is 19.2 years [ 0450 ]. ... [ 0450 ] Fransson et al. (2010), EURING list of longevity records for European birds

Source
04

The IUCN Red List of Threatened Species 2021

Podiceps cristatus. The IUCN Red List of Threatened Species 2021: e.T22696602A166312625.

The page saysIUCN rates it Least Concern
The source saysLeast Concern (LC)Note: GBIF's copy of the Red List, checked against the taxon id in the DOI

Source
05

Huxley 1914

Huxley (1914). The Courtship-habits of the Great Crested Grebe (Podiceps cristatus), with an Addition to the Theory of Sexual Selection. Proceedings of the Zoological Society of London.

The page saysThe biologist Julian Huxley described these displays in 1914 and gave their parts names
The source saysBy Julian S. Huxley", B.A., Professor of Biology in the Bice Institute ... [Received March 14, 1914 : Read April 21, 1914.]Note: Huxley's title in the paper: Professor of Biology in the Rice Institute (OCR 'Bice'). The names themselves are the weed-trick and Penguin-dance claims.
The page saysIn one display he watched, each bird gave about a dozen or fifteen violent shakes
The source saysafter each bird had given about a dozen or fifteen violent shakes
The page saysHe called diving for water-weed and appearing again with it in the bill the "weed-trick."
The source saysLet us call the diving for water-weed and the appearing again with it in the bill the weed-trick
The page saysHe also watched a pair surface holding weed, swim toward each other and rise quickly from the water into an almost erect position, their breasts touching
The source saysboth were holding in their beaks a bunch of dark ribbony weed ... swam straight towards him at a good pace ... made off to meet her ... they both sprang up from the water into an almost erect position ... a very quick rising-up of the birds ... the two birds came actually to touch each other with their breasts
The page saysrocking gently from side to side "as if they were swaying to the music of a dance."
The source saysthey stayed for a few seconds rocking ... from side to side upon the point of their breasts ; it was an ecstatic motion, as if they were swaying to the music of a danceNote: the OCR reads 'gentty' for 'gently', so the quote skips that word
The page saysHe called the rapid swimming together and the erect breast-to-breast figure that follows the "Penguin-dance," because the general resemblance to penguins "forced itself upon the mind."
The source saysthe rapid swimming ... subsequent figure erect ... to breast, let us call the Penguin-dance , for here once more the general resemblance to Penguins ... forced itself upon the mindNote: the OCR mangles 'together' and 'breast-to-breast' ('brea,st-to-breast'), so the quote is fragmented around them
The page saysto a breast-to-breast 'Penguin-dance,'
The source saysthe rapid swimming ... subsequent figure erect ... to breast, let us call the Penguin-dance
The page saysA head-shaking courtship duet that can include a breast-to-breast 'Penguin-dance'
The source saysthe rapid swimming ... subsequent figure erect ... to breast, let us call the Penguin-danceNote: 'duet' is ADW's communication-mode tag ('Other Communication Modes duets'); head-shaking is the ADW courtship claim above
The page saysThe biologist Julian Huxley gave the parts of the grebe's courtship names in 1914
The source saysBy Julian S. Huxley", B.A., Professor of Biology in the Bice Institute ... [Received March 14, 1914 : Read April 21, 1914.]Note: Huxley's title in the paper: Professor of Biology in the Rice Institute (OCR 'Bice'). The names themselves are the weed-trick and Penguin-dance claims.
The page saysDiving for water-weed and surfacing with it in the bill was the 'weed-trick.'
The source saysLet us call the diving for water-weed and the appearing again with it in the bill the weed-trick
The page saysThe rapid swimming together and the erect breast-to-breast figure that follows was the 'Penguin-dance,' because the general resemblance to penguins 'forced itself upon the mind.'
The source saysthe rapid swimming ... subsequent figure erect ... to breast, let us call the Penguin-dance , for here once more the general resemblance to Penguins ... forced itself upon the mind
The page saysIn one pair he watched, the two birds held that pose for a few seconds, rocking gently from side to side 'as if they were swaying to the music of a dance.'
The source saysthey stayed for a few seconds rocking ... from side to side upon the point of their breasts ; it was an ecstatic motion, as if they were swaying to the music of a dance
The page saysthey dive for water-weed and rise breast to breast in what Julian Huxley named the Penguin-dance
The source saysLet us call the diving for water-weed and the appearing again with it in the bill the weed-trickNote: vibe.reason, settled in #836; the Penguin-dance naming is claimed on the page from the same paper.

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.