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What the sources say

Mountain GorillaGorilla beringei beringei

Every figure, record and mechanism on the Mountain Gorilla profile was written from a source, and this is the working table behind it: 44 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

Wright et al. 2021

Wright et al. (2021). Chest beats as an honest signal of body size in male mountain gorillas (Gorilla beringei beringei). Scientific Reports.

The page saysa chest beat heard more than a kilometer away
The source saysThis multimodal long-distance signal, which can be heard over 1 km away
The page saysA chest-beat drumroll that can be heard more than a kilometer away, pitched lower the bigger the male beating it
The source saysThis multimodal long-distance signal, which can be heard over 1 km away ... The chest beat of larger males comprised significantly lower peak frequencies than smaller males
The page sayshe usually rises onto two legs and beats his chest with cupped hands, producing a drumroll that can be heard more than a kilometer away
The source saysChest beating is performed when individuals usually rise bipedally and rapidly beat their chests with cupped hands in rapid succession, producing an impressive drumming sound ... which can be heard over 1 km away
The page saysResearchers who recorded six wild silverbacks in Rwanda's Volcanoes National Park
The source saysVolcanoes National Park, Rwanda ... six adult males from two social groups
The page saysfound that bigger males beat at a lower pitch than smaller ones
The source saysThe chest beat of larger males comprised significantly lower peak frequencies than smaller males
The page saysAcross the six, the average peak pitch was about 639 Hz
The source saysThe mean peak frequency per male was 638.9 HzNote: 639 rounds 638.9
The page saysThat makes the chest beat an honest signal
The source sayswe conclude that the gorilla chest beat is an honest signal of competitive ability
The page saysthe sound itself carries information about how big the drummer is
The source sayswe have demonstrated that chest beats reliably convey the body size of the emitter
The page saysChest beats are thought to help males judge a rival's fighting ability, though the researchers say future studies still need to show that listening gorillas use it
The source saysfuture studies need to show that receivers actually attend to this information. Gorilla chest beats are thought to play a key role in male–male competition allowing individuals to assess the fighting ability of competitors
The page saysThe bigger the silverback, the lower the pitch of his chest beat
The source saysThe chest beat of larger males comprised significantly lower peak frequencies than smaller males
The page saysResearchers call that an honest signal
The source sayswe conclude that the gorilla chest beat is an honest signal of competitive ability
The page saysit can be heard more than a kilometer away
The source sayswhich can be heard over 1 km away
The page saysSilverbacks usually rise onto two legs and slap cupped hands against their chest, producing a drumroll that can be heard more than a kilometer away
The source saysChest beating is performed when individuals usually rise bipedally and rapidly beat their chests with cupped hands in rapid succession, producing an impressive drumming sound ... which can be heard over 1 km away
The page saysRecordings of six wild silverbacks in Rwanda
The source saysVolcanoes National Park, Rwanda ... six adult males from two social groups
The page saysbigger males beat at a lower pitch than smaller ones, so the sound carries honest information about a male's size
The source saysThe chest beat of larger males comprised significantly lower peak frequencies than smaller males
The page saysChest beats are thought to help males size up rivals, though researchers still need to show that listening gorillas actually use that information
The source saysfuture studies need to show that receivers actually attend to this information. Gorilla chest beats are thought to play a key role in male–male competition allowing individuals to assess the fighting ability of competitors
The page saysusually rises onto two legs and beats his chest with cupped hands into a drumroll heard more than a kilometer away
The source saysChest beating is performed when individuals usually rise bipedally and rapidly beat their chests with cupped hands in rapid succession, producing an impressive drumming sound ... which can be heard over 1 km awayNote: vibe.reason (#692/#693)
The page saysThe bigger the male, the lower the pitch
The source saysThis multimodal long-distance signal, which can be heard over 1 km away ... The chest beat of larger males comprised significantly lower peak frequencies than smaller malesNote: vibe.reason (#692/#693)

Source
02

Elgart-Berry 2004

Elgart-Berry (2004). Fracture toughness of mountain gorilla (Gorilla gorilla beringei) food plants. American Journal of Primatology.

The page saysa study of food plants from Bwindi Impenetrable and Mgahinga Gorilla National Parks measured its fracture toughness at up to 8.2 kilojoules per square meter, tougher than the leaves and bamboo gorillas also eat
The source saysSamples of 44 food plants from Bwindi-Impenetrable National Park (BINP) and Mgahinga Gorilla National Park (MGNP) were tested ... Tree barks were the toughest food items (varying from 0.23 to 8.2 kJ/m2) ... The toughness of leaves and fruit was negligible compared to that of bark. The toughness of bamboo was low in comparison to the toughest food items.
The page saysThe researchers suggest that tough bark, pith, and stems may be key reasons mountain gorillas evolved such robust jaws and faces
The source saysthe prominent toughness of bark, pith, and stems may be key factors in the evolution of orofacial robusticity in mountain gorillas

Source
03

McFarlin et al. 2026

McFarlin et al. (2026). Variation in body size growth trajectories between ecologically distinct mountain gorilla populations. Proceedings of the Royal Society B: Biological Sciences.

The page saysA 2026 study comparing gorillas from Bwindi and the Virungas found that males from the two places end up almost the same adult size, while Bwindi females stay smaller and keep growing for longer
The source saysBwindi females attained a smaller adult size than Virunga females, despite continuing their growth over a longer duration. Population differences in male adult size were minimalNote: 2026 is the reference's publication year

Source
04

Animal Diversity Web, University of Michigan 2001

Gorilla beringei (eastern gorilla). Animal Diversity Web, University of Michigan, 2001.

The page saysIn the Virunga volcanoes, which separate the Democratic Republic of Congo from Rwanda and Uganda, they mostly live in montane cloud forest, and sometimes climb as high as 4,000 meters into afro-alpine meadows where nights turn subfreezing and there is little food to forage
The source saysare found in the Virunga volcanoes that separate the Democratic Republic of Congo from Rwanda and Uganda. ... Mountain gorillas inhabit the montane cloud forest of the Virunga range. Occasionally they go into the afro-alpine meadows (4,000 m) where temperatures are subfreezing at night and there is little suitable food to forage on.
The page saysTheir hair is longer than other gorillas'
The source saysMountain gorillas differ from other gorillas in having longer hair
The page saysMountain gorillas have longer hair than other gorillas
The source saysMountain gorillas differ from other gorillas in having longer hair
The page saysThey mostly live in the montane cloud forest of the Virunga volcanoes, but sometimes climb to 4,000 meters into afro-alpine meadows, where nights drop below freezing and there is little to eat
The source saysMountain gorillas inhabit the montane cloud forest of the Virunga range. Occasionally they go into the afro-alpine meadows (4,000 m) where temperatures are subfreezing at night and there is little suitable food to forage on.

Source
05

African Wildlife Foundation

Mountain Gorilla. African Wildlife Foundation.

The page saysUp to 220 kilograms
The source saysWeight 135 to 220 kilograms (300 to 485 pounds)
The page saysthe only great ape whose numbers are growing
The source saysOnly great ape with increasing population
The page saysCloud forests and dense bamboo slopes of the Virunga volcanic mountains and Bwindi Impenetrable Forest
The source saysDense forest, rainforest, bamboo forest, mixed forest, subalpine grassland on the volcanic peaksNote: cloud forest: adw-gorilla-beringei 'montane cloud forest of the Virunga range'; Bwindi is in this source's park list
The page saysWild celery, bamboo, thistles, wood, and roots
The source saysThey favor celery, thistles, wood, and rootsNote: bamboo: elgart-berry-2004 tested bamboo among the gorillas' food plants
The page saysis one of two subspecies of the eastern gorilla
The source saysThis great ape is one of two subspecies of the eastern gorilla
The page saysA mountain gorilla eats up to 18 kilograms (40 pounds) of vegetation a day
The source saysThese great apes can eat as much as 18 kg (40 lb) of vegetation each day.
The page saysIts favorites include celery, thistles, wood, and roots, and it rarely needs to drink, because its juicy food and the morning dew on it are full of water
The source saysThey favor celery, thistles, wood, and roots, and they rarely need to drink because they consume succulent vegetation which is full of water as well as morning dew
The page saysMountain gorillas live in three countries, across just four national parks: Bwindi Impenetrable, Mgahinga Gorilla, Volcanoes, and Virunga
The source saysThese great apes live in three countries spanning four national parks — Bwindi Impenetrable National Park, Mgahinga Gorilla National Park, Volcanoes National Park, and Virunga National Park.
The page saysthat thick black coat helps insulate them from the cold
The source saysTheir thick black hair helps insulate them from cold weather.
The page saysThe IUCN moved mountain gorillas from Critically Endangered to Endangered in 2018
The source saysDeclared endangered in 2018 by IUCN ... The biggest threats to this once critically endangered great ape's survival
The page saysAbout 1,000 live in the wild, according to the most recent census
The source saysOnly about 1,000 of these great apes remain in the wild, according to the most recent census.
The page saysthey are the only great ape whose population is increasing
The source saysOnly great ape with increasing population
The page saysThey live in groups of 2 to 40, each led by a silverback
The source sayslive in groups of two to 40 led by the silverbackNote: 2 is the source's 'two'
The page saysPoachers often target infants
The source saysUnfortunately, infants are often targeted by poachers.
The page saysconflict in the Democratic Republic of Congo threatens the gorillas' future
The source saysA future marred by conflict. War in the Democratic Republic of Congo
The page saysAs more people move in close to the gorillas, they bring the risk of human diseases such as flu and pneumonia
The source saysAs people move closer to these endangered apes, they also bring the risk of human diseases such as the flu, pneumonia, and even Ebola.
The page saysUp to 18 kilograms (40 pounds) of vegetation a day
The source saysThese great apes can eat as much as 18 kg (40 lb) of vegetation each day.
The page saysTheir favorites include celery, thistles, wood, and roots, and they rarely need to drink, because their juicy plants and the morning dew on them are full of water
The source saysThey favor celery, thistles, wood, and roots, and they rarely need to drink because they consume succulent vegetation which is full of water as well as morning dew
The page saysthat thick black hair helps insulate them from the cold
The source saysTheir thick black hair helps insulate them from cold weather.

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.