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Self‑destructive behavior among Hermann's tortoises on a Macedonian island is leading to 'demographic suicide'

Phys · · 1540 words · By Xavier Bonnet
Animal Behavior Population Dynamics Wildlife Conservation

Researchers have observed a population of Hermann's tortoises on Golem Grad island in North Macedonia experiencing a severe sex-ratio imbalance. The study suggests that aggressive male behavior, including pushing females off cliffs, is creating a 'demographic suicide' loop that may lead to the population's extinction.

open_in_new Read the original article: https://phys.org/news/2026-05-selfdestructive-behavior-hermann-tortoises-macedon…

analyticsAnalysis

20%
Propaganda Score
confidence: 95%
Minor concerns. Some persuasive language detected, but largely factual.

psychologyDetected Techniques

warning
Loaded Language 80% confidence
Using words with strong emotional connotations to influence an audience.
warning
Exaggeration / Hyperbole 70% confidence
Overstating facts or claims to create a stronger emotional response.

fact_checkFact-Check Results

15 claims extracted and verified against multiple sources including cross-references, web search, and Wikipedia.

schedule Pending 5
check_circle Corroborated 4
info Single Source 2
help Insufficient Evidence 2
cancel Disputed 1
verified Verified 1
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“On the strictly protected island of Golem Grad in North Macedonia, the tortoises are destroying their own population.”
CORROBORATED
Multiple independent web search results confirm that Hermann's tortoises on Golem Grad are experiencing a population decline due to self-destructive behavior and sex imbalance.
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wikipedia NEUTRAL — Over 22,500 species of wildlife have been recorded in North Macedonia. Over 10,000 of these are insects, which include 3,000 beetle species and large numbers of Lepidoptera, flies, and Hymenoptera. As…
https://en.wikipedia.org/wiki/Wildlife_of_North_Macedonia
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wikipedia NEUTRAL — Golem Grad (Macedonian: Голем Град), meaning Big City/Town, also known as Snake Island or Pelican Island, is an island in North Macedonia. The island covers an area of more than 20 hectares. It is loc…
https://en.wikipedia.org/wiki/Golem_Grad
travel_explore
web search NEUTRAL — Golem Grad island in North Macedonia is full of Hermann’s tortoises. However, demographic projections suggest the last female could be wiped out by 2083.On the strictly protected island of Golem Grad …
https://theconversation.com/self-destructive-behaviour-among…
+ 2 more evidence sources
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“aggressive males are exhausting the females and frequently pushing them off the cliffs.”
CORROBORATED
Multiple sources explicitly state that aggressive males exhaust females and push them off cliffs during courtship.
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wikipedia NEUTRAL — Golem Grad (Macedonian: Голем Град), meaning Big City/Town, also known as Snake Island or Pelican Island, is an island in North Macedonia. The island covers an area of more than 20 hectares. It is loc…
https://en.wikipedia.org/wiki/Golem_Grad
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web search NEUTRAL — Golem Grad is home to around 1000 Hermann's tortoises, which were introduced by humans to the island. Due to genetic variation or an initial imbalance in sex when they were first introduced, the torto…
https://en.wikipedia.org/wiki/Golem_Grad
travel_explore
web search NEUTRAL — Golem Grad island in North Macedonia is full of Hermann’s tortoises. However, demographic projections suggest the last female could be wiped out by 2083.During prolonged courtship, aggressive males ar…
https://theconversation.com/self-destructive-behaviour-among…
+ 1 more evidence source
cancel
“there are now one hundred males for every female capable of laying eggs.”
DISPUTED
The claim states a ratio of 100 males per female. However, multiple evidence sources report a ratio of 'up to 19 males to every female' or '19 to 1', which contradicts the 100:1 claim.
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wikipedia NEUTRAL — Grad (Cyrillic: град) is an Old Slavic word meaning "town", "city", "castle" or "fortified settlement". Initially present in all related languages as gord, it can still be found as grad, gradić, horod…
https://en.wikipedia.org/wiki/Grad_(toponymy)
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wikipedia NEUTRAL — A golem is an artificial animated being in medieval and Jewish folklore. Golem or The Golem may also refer to:
https://en.wikipedia.org/wiki/Golem_(disambiguation)
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wikipedia NEUTRAL — Golem Grad (Macedonian: Голем Град), meaning Big City/Town, also known as Snake Island or Pelican Island, is an island in North Macedonia. The island covers an area of more than 20 hectares. It is loc…
https://en.wikipedia.org/wiki/Golem_Grad
+ 3 more evidence sources
info
“This is the only known example of demographic suicide in the wild to date.”
SINGLE SOURCE
The specific phrasing that this is the 'only known example of demographic suicide in the wild to date' appears in one specific source title/snippet, while other sources discuss the imbalance without confirming it is the 'only' such case globally.
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wikipedia NEUTRAL — A golem is an artificial animated being in medieval and Jewish folklore. Golem or The Golem may also refer to:
https://en.wikipedia.org/wiki/Golem_(disambiguation)
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wikipedia NEUTRAL — Golem Grad (Macedonian: Голем Град), meaning Big City/Town, also known as Snake Island or Pelican Island, is an island in North Macedonia. The island covers an area of more than 20 hectares. It is loc…
https://en.wikipedia.org/wiki/Golem_Grad
menu_book
wikipedia NEUTRAL — Grad (Cyrillic: град) is an Old Slavic word meaning "town", "city", "castle" or "fortified settlement". Initially present in all related languages as gord, it can still be found as grad, gradić, horod…
https://en.wikipedia.org/wiki/Grad_(toponymy)
+ 3 more evidence sources
verified
“Hermann's tortoises (Testudo hermanni boettgeri) thrive on the wooded plateau [of Golem Grad].”
VERIFIED
Web results confirm that Testudo hermanni boettgeri is a recognized subspecies and that Golem Grad is inhabited by Hermann's tortoises.
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web search NEUTRAL — Testudo hermanni boettgeri, Mojsisovics 1889. [Bearbeiten | Quelltext bearbeiten]. Der Rückenpanzer von T. h. boettgeri ist etwas weniger hochgewölbt als bei der westlichen Unterart.
https://de.wikipedia.org/wiki/Griechische_Landschildkröte
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web search NEUTRAL — Biotype, nomenclature and taxonomic diagnostic characters of Testudo hermanni hermanni GMELIN 1789 in Southern France with preliminary notes on comparative egg morphology with T. h. boettgeri MOJSISOV…
https://www.tortoisetrust.org/articles/biohermanni.html
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web search NEUTRAL — Hermann’s tortoise (Testudo hermanni) is listed as “Near threatened” in the IUCN Red list of endangered species.The high number of islands with introduced individuals is associated with the tendency o…
https://herpetozoa.pensoft.net/article/103510/list/18
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“On Golem Grad, the adults have no predators, as wild boars, dogs, rats and humans are absent from this strictly protected island.”
CORROBORATED
Sources confirm the island is uninhabited by humans and is a protected natural laboratory, though the specific list of absent animals (boars, dogs, rats) is partially corroborated by the general 'uninhabited' status.
travel_explore
web search NEUTRAL — The only island in landlocked Macedonia is uninhabited… at least by humans. Located in the south of Lake Prespa, near the Albanian border, Golem Grad is frequently referred to as “Snake Island.” Our e…
https://macedonia.for91days.com/golem-grad-better-known-as-s…
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web search NEUTRAL — On Golem Grad island, at each capture and recapture event, researchers measure the individual’s body mass and size, note the exact location, note behaviour at capture, take additional morphological me…
https://www.pont.org/golem-grad-island-a-world-class-natural…
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web search NEUTRAL — Golem Grad, the only natural island in the Republic of Macedonia, is located on Lake Prespa in the southwestern region of MacedoniaGolem Grad also commonly referred to as “Snake Island”, for the seaso…
https://journeymacedonia.com/scenic/golem-grad-snake-island/
info
“The mild Mediterranean climate of this lake, situated at an altitude of 850 meters, is also favorable for reptiles.”
SINGLE SOURCE
The provided evidence for this claim contains generic definitions of lakes and does not mention the altitude of Lake Prespa or its climate.
travel_explore
web search NEUTRAL — Lake Idro, an Italian prealpine lake of glacial origin situated largely within the province of Brescia (Lombardy) and in part in Trentino. Sunset over Lake Michigan at Nordhouse Dunes in Manistee Nati…
https://en.wikipedia.org/wiki/Lake
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web search NEUTRAL — Apr 1, 2026 · What is a lake? Learn the clear definition, how lakes form, how they differ from ponds and reservoirs, and why lakes matter in geography.
https://geographypin.com/what-is-a-lake/
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web search NEUTRAL — View maps of Lake Serene and the surrounding area, including the location of public access sites. Summary of Lake Serene health and recreational opportunities.
https://snohomishcountywa.gov/5388/Serene
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“extraordinary population density, which stands at around 50 individuals per hectare—the highest ever recorded for tortoises.”
CORROBORATED
Two separate web search snippets explicitly state the population density is around 50 individuals per hectare and that this is the highest ever recorded for tortoises.
travel_explore
web search NEUTRAL — Golem Grad (Macedonian: Голем Град), meaning Big City/Town, also known as Snake Island or Pelican Island, is an island in North Macedonia. The island covers an area of more than 20 hectares. [1]
https://en.wikipedia.org/wiki/Golem_Grad
travel_explore
web search NEUTRAL — All these factors explain the extraordinary population density, which stands at around 50 individuals per hectare—the highest ever recorded for tortoises.
https://phys.org/news/2026-05-selfdestructive-behavior-herma…
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web search NEUTRAL — All these factors explain the extraordinary population density, which stands at around 50 individuals per hectare - the highest ever recorded for tortoises.
https://theconversation.com/self-destructive-behaviour-among…
help
“the establishment of the field-monitoring program in 2008... this long-term monitoring program was awarded the CNRS's SEE-Life label in 2023.”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results regarding the 2008 monitoring program or the 2023 CNRS SEE-Life label.
help
“On the plateau, over 700 adult males roam around looking for the forty or so adult females.”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results specifying the exact count of 700 males and 40 females.
schedule
“On July 18 2023, a GPS device fitted with an accelerometer, attached to a female, recorded her fall of over 20 meters; she died, broken in two, along with her three eggs.”
PENDING
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“Of the females that died, 22% suffered a fatal fall, compared to 7% of the males.”
PENDING
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“The oldest males are over 60 years old and the oldest female is 35.”
PENDING
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“In 2009, we captured 45 adult females in the field, compared to 37 in 2010, 20 in 2024, and just 15 in 2025.”
PENDING
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“it takes a female around fifteen years to reach adulthood.”
PENDING
info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.