{"id":211393,"date":"2025-10-14T03:32:11","date_gmt":"2025-10-14T03:32:11","guid":{"rendered":"https:\/\/www.newsbeep.com\/ca\/211393\/"},"modified":"2025-10-14T03:32:11","modified_gmt":"2025-10-14T03:32:11","slug":"ecosystem-killers-10-destructive-brutal-animals-that-destroy-entire-habitats","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ca\/211393\/","title":{"rendered":"Ecosystem killers: 10 destructive, brutal animals that destroy entire habitats"},"content":{"rendered":"

Indiscriminate predators,\u00a0insatiable grazers,\u00a0ecosystem engineers<\/a>, flagrant opportunists and invasive horrors\u2026 here\u2019s our pick of the animals great and small that\u00a0can\u00a0change\u00a0the world around them\u00a0beyond recognition\u00a0\u2013 and not in a good way.<\/p>\n

10 animals that destroy entire ecosystems
\nBrown tree snake
\n\"\"Gordon H. Rodda, Public domain, via Wikimedia Commons<\/p>\n

The remote Pacific island of Guam was serpent-free until around 1950 when the brown tree snake arrived from somewhere in its native range to the south.\u00a0<\/p>\n

However it got there \u2013 most likely as a stowaway on a boat or plane – it found a land teeming with birds, reptiles and bats that had no defences against its predatory instincts. By the time authorities started monitoring the situation in the 1980s, there were more than 100 snakes per hectare and much of the damage had already been done.\u00a0<\/p>\n

By 1990, just three species of native vertebrates \u2013 all small lizards \u2013 remained in significant numbers in the island\u2019s forests. The snake wiped out 12 of the 22 native bird species, including the\u00a0Guam flycatcher, which was found nowhere else in the world, and reduced numbers of another eight species by at least 90 per cent. It drove six native lizards to extinction and is also implicated in the disappearance of the endemic Guam flying fox, which was last seen in 1968.<\/p>\n

Unsurprisingly, this ecological disaster has had dramatic consequences for the island\u2019s wider ecology. Bird-pollinated plants are now setting fewer seeds, and loss of the vertebrates that disperse seeds is changing the species composition of the island\u2019s forests. Meanwhile, spider populations have increased 40-fold during the wet season since their avian predators disappeared.\u00a0<\/p>\n

Cane toad
\n\"AJason Edwards\/Getty<\/p>\n

Sometimes, a cure can be more dangerous than the disease it\u2019s meant to be treating. That is surely the case with the cane toad<\/a>, a native of South and Central America that was transported to Australia in the 1930s to control beetles plaguing the sugarcane crops.\u00a0<\/p>\n

Unfortunately, these\u00a0gluttonous\u00a0amphibians hunt on the ground, so they made little impact on the beetles, which feed high up on the plants. Instead, the toads turned their attentions to the native wildlife,\u00a0swallowing\u00a0pretty much anything that would\u00a0fit in their mouths\u00a0–\u00a0insects, frogs, reptiles, and small birds and mammals.<\/p>\n

But cane toads are not only dangerous, indiscriminate predators; they are also lethal prey.\u00a0Quolls\u00a0(predatory marsupials<\/a>), goannas (a type of large monitor lizard), snakes and\u00a0even\u00a0freshwater crocodiles\u00a0can be killed by the potent toxins secreted by glands on the frogs\u2019 skin.\u00a0<\/p>\n

In many invaded areas,\u00a0quolls\u00a0have vanished and\u00a0goannas have crashed by morethan 90 per cent. The cane toad is a species that can wreak havoc at both ends of the food chain.<\/p>\n

Beaver
\n\"\"Getty<\/p>\n

This big, bucktoothed rodent is hailed for its ability to create habitats rather than destroy them. By felling trees and damming streams, it engineers wetland ecosystems that boost aquatic biodiversity<\/a> and double as\u00a0natural flood defences.<\/p>\n

But you can\u2019t make an omelette without breaking eggs. Valleys that once held bubbling streams,\u00a0shady woodland\u00a0and wildflower meadows\u00a0become\u00a0quite literally swamped\u00a0by\u00a0standing water. Trees die, dams block the passage of migratory fish, and species\u00a0that\u00a0require flowing water\u00a0quietly disappear.<\/p>\n

In the beaver\u2019s\u00a0native ranges, these trade-offs are part of\u00a0long-established\u00a0ecological processes.\u00a0In places where beavers don\u2019t belong, though, the downsides can be more striking. Beavers\u00a0introduced\u00a0from North to South America\u00a0have destroyed swathes of\u00a0native\u00a0beech forest in Tierra del Fuego.<\/p>\n

Whether you see the activities of these quintessential ecosystem engineers as creative or\u00a0destructive depends\u00a0on where you stand when the water starts to rise.<\/p>\n

Rosy wolf snail
\n\"\"Dylan Parker, CC BY-SA 2.0 https:\/\/creativecommons.org\/licenses\/by-sa\/2.0, via Wikimedia Commons<\/p>\n

The vast majority of terrestrial snails are vegetarians, and for good reason.\u00a0Predators need to be fast, and\u00a0yet\u00a0speed is not something snails are known for.\u00a0The\u00a0rosy wolf snail, though, is very much a hunter. While it\u2019s\u00a0not\u00a0exactly\u00a0nippy, it is, crucially,\u00a0faster than its prey \u2013 other snails,\u00a0which\u00a0it hunts down by following their slime trails.<\/p>\n

Native to\u00a0the\u00a0southeastern\u00a0United States,\u00a0the rosy wolf snail\u00a0was introduced\u00a0to\u00a0a number of\u00a0Pacific islands, including Tahiti and\u00a0Hawaii,\u00a0in the mid-20th century in the hope that it would control\u00a0the giant African land snail, which\u00a0had become\u00a0an\u00a0invasive\u00a0agricultural pest\u00a0after its own introduction.<\/p>\n

Tragically, the rosy wolf snail turned out to prefer easier pickings –\u00a0the small,\u00a0delicate native snails that had been evolving in splendid isolation\u00a0on the various islands\u00a0for hundreds of thousands of years.\u00a0A\u00a0massacre\u00a0ensued.\u00a0More than 130 native snailspecies\u00a0were driven to extinction\u00a0within decades.\u00a0<\/p>\n

Rats
\n\"\"Getty<\/p>\n

Opportunistic and adaptable, rats seem\u00a0to flourish wherever life takes them. They areagile climbers, strong swimmers,\u00a0fiercely\u00a0intelligent,\u00a0prolific\u00a0breeders,\u00a0catholic in their tastes, and\u00a0have\u00a0a knack for\u00a0availing themselves of human modes of transportation.<\/p>\n

Between them, the black rat,\u00a0brown rat and Pacific rat \u2013 all originally native to south and eastern Asia –\u00a0now infest more than 80 per cent of the world\u2019s islands. And the transformation of habitats begins as soon as they have hopped\u00a0ashore.<\/p>\n

Globally, rats are implicated in the extinction of more than 70 vertebrate species.\u00a0In\u00a0the\u00a0Chagos\u00a0Archipelago\u00a0in the Indian Ocean,\u00a0the densities of seabirds on\u00a0rat-free islands are 760 times\u00a0higher than\u00a0on\u00a0infested ones.\u00a0<\/p>\n

This has had dramatic effects on the wider ecosystem, which has historically been\u00a0nourished\u00a0by\u00a0the guano depositedby the\u00a0resident\u00a0bird colonies.\u00a0Even the\u00a0coastal waters are affected, to the extent that the coral reefs fringing rat-free islands support around 50 per cent more fish.<\/p>\n

Nile perch
\n\"\"Daiju Azuma, CC BY-SA 4.0 https:\/\/creativecommons.org\/licenses\/by-sa\/4.0, via Wikimedia Commons<\/p>\n

Few introductions have caused such havoc as the Nile perch\u2019s release into Lake Victoria\u00a0in East Africa\u00a0in the 1950s. This giant predator, growing more than two metres long, was meant to boost fisheries.\u00a0Arguably, it succeeded – but at a huge ecological cost.<\/p>\n

In the 15,000 years since climatic changes created the world\u2019s second largest lake, evolution has\u00a0worked\u00a0its magic on\u00a0a population of cichlid fish\u00a0that\u00a0arrived there soon after its formation.\u00a0These founding mothers and fathers\u00a0multiplied,\u00a0dispersed and\u00a0diversified to fill\u00a0a multitude of specialised niches. While some\u00a0took to hunting\u00a0in the open water or scraping\u00a0algae from rocks,\u00a0others\u00a0strained particles from the sediment, crushed molluscs or scavenged at the surface. A\u00a0few even\u00a0specialised in nibbling\u00a0the fins and scales of their neighbours.<\/p>\n

Add to that the gaudy colours and elaborate courtship rituals that set species apart, and\u00a0the result was\u00a0a\u00a0living\u00a0evolutionary\u00a0laboratory\u00a0unrivalled anywhere in freshwater.<\/p>\n

To the\u00a0Nile\u00a0perch, though, it was all just food.\u00a0Within\u00a0a few\u00a0decades, as many as 200 of the lake\u2019s cichlid species were extinct.\u00a0Many others\u00a0now cling\u00a0on in tiny populations, while some survive only in aquaria.\u00a0<\/p>\n

European rabbit
\n\"\"Getty<\/p>\n

Don\u2019t be fooled by the endearing twitchy nose and photogenic\u00a0dandelion-nibbling, the European rabbit has\u00a0proved capable of causing\u00a0ecological devastation\u00a0around the world.<\/p>\n

Native to the Iberian Peninsula,\u00a0it has\u00a0been introduced to all continents except Antarctica for its fur and\u00a0as a game animal.\u00a0Most infamously, perhaps,\u00a0a handful released\u00a0in\u00a0Australia\u00a0in the 1850s soon became\u00a0hundreds of millions,\u00a0which\u00a0gnawedthrough crops\u00a0and native vegetation, stripping\u00a0landscapes\u00a0bare and turning fertile soils to dust. The problem was so overwhelming that authorities built the rabbit-proof fence –\u00a0the longest continuous barrier in the world at the time,\u00a0at over 3,000 km\u00a0–\u00a0in a vain attempt to hold back the tide.<\/p>\n

New Zealand fared little\u00a0better, and the destruction was compounded by\u00a0efforts to control them with\u00a0introduced\u00a0stoats and weasels. These\u00a0had\u00a0a modest effect\u00a0on the rabbits but\u00a0tragic\u00a0consequences for native birds, including\u00a0the laughing owl, which was driven to extinction by the early 20th century.<\/p>\n

Domestic cat<\/p>\n

People\u00a0have long enjoyed\u00a0having cats around the place, not only for\u00a0their company, but also for\u00a0their\u00a0rodent-control\u00a0skills.\u00a0Unfortunately, they don\u2019t\u00a0stop at eating\u00a0just vermin.<\/p>\n

In the US alone,\u00a0pet and feral cats kill an estimated 1.3 to\u00a04\u00a0billion birds\u00a0every year, and cats introduced to islands\u00a0around the world\u00a0are implicated in\u00a014 per cent\u00a0of\u00a0all\u00a0the bird, mammal and reptile extinctions\u00a0in modern times.<\/p>\n

Take what happened on\u00a0Stephens Island\u00a0in the Cook Strait between New Zealand\u2019s North and South islands.\u00a0Until the 1890s it\u00a0was an uninhabited\u00a0pristine refuge for many species that had\u00a0already\u00a0been ravaged by the Polynesian rat, which hadarrived\u00a0with the Maoris.\u00a0<\/p>\n

But when\u00a0a new\u00a0lighthouse\u00a0was switched on in 1894, the island became home to\u00a0three lighthouse-keepers, their families, a teacher for the\u00a0children, and a succession of\u00a0pet cats that quickly spawned\u00a0a\u00a0feral\u00a0population\u00a0that feasted on the island\u2019s birdlife and reptiles such as the tuatara, the sole living representative of an ancient lineage of lizard-like animals\u00a0that had already been eliminated from the mainland. The\u00a0Stephens Island wren \u2013\u00a0a tiny, flightless songbird found nowhere else\u00a0on Earth\u00a0\u2013\u00a0was first described from a specimen killed by one of the cats, and seems to have disappeared completely by 1899.<\/p>\n

The\u00a0feral\u00a0cats were finally eradicated\u00a0from\u00a0the island\u00a0by 2025,\u00a0in a pioneering effort that provided\u00a0an early lesson in how habitats can be restored\u00a0to their former glory.\u00a0Seabird and reptile populations\u00a0have rebounded,\u00a0and the tuatara recovered to the point that individuals could be shipped to other islands. The wren, though, is gone forever.<\/p>\n

Feral goat
\n\"\"Getty<\/p>\n

A century after the removal of cats from Stephens Island,\u00a0habitat restoration\u00a0efforts have become\u00a0increasingly ambitious.\u00a0A case in point is\u00a0Project\u00a0Isabela,\u00a0which aims\u00a0to eradicate\u00a0hundreds of thousands of\u00a0feral goats from the\u00a0Gal\u00e1pagos\u00a0archipelago.\u00a0<\/p>\n

When goats arrived in the\u00a0islands\u00a0during the 1600s \u2013 deposited there by passing sailors as a living food store \u2013 the only native terrestrial mammals were a few species of bat. The islands would later become famous\u00a0for the\u00a0endemic\u00a0birds and reptiles\u00a0that\u00a0were so influential on the development of\u00a0Darwin\u2019s ideas on the mechanism of evolution<\/a>.\u00a0But as the goats multiplied, they posed an increasing threat to\u00a0the\u00a0native habitats\u00a0on which the iconic finches and giant tortoises depend.<\/p>\n

Goats\u00a0are hardy and\u00a0adaptable\u00a0and\u00a0their digestive systems can deal\u00a0with plant toxins that would kill other\u00a0herbivores, allowing them to\u00a0eat anything and everything\u00a0of a botanical nature.\u00a0On some islands,\u00a0vast tracts have been stripped of vegetation and turned to dust, while forest trees have been unable to reproduce because the goats eat each and every seedling.\u00a0<\/p>\n

Project\u00a0Isabela\u00a0is not yet complete.\u00a0More than 140,000 goats\u00a0have been removed\u00a0from 400,000ha of land\u00a0at a cost of at least\u00a0$10.5 million,\u00a0but they\u00a0continue to roam on three islands.\u00a0<\/p>\n

Red grouse
\n\"\"Getty<\/p>\n

It is neither\u00a0an invader\u00a0nor especially destructive in its own right, but\u00a0the\u00a0red grouse\u00a0has managed to reconfigure\u00a0the\u00a0landscape\u00a0of pretty much an entire country.\u00a0Or more accurately,\u00a0perhaps,\u00a0the landscape has been reconfigured around it.\u00a0<\/p>\n

Native to the uplands of Britain and Ireland \u2013 and, indeed, found nowhere else in the world – the bird\u00a0has long\u00a0been hunted as game, and\u00a0grouse-shooting\u00a0has becomeincreasingly commercialised over the past couple of centuries.<\/p>\n

To keep grouse\u00a0numbers high, vast tracts of the Scottish Highlands are managed as heather moorland.\u00a0Since\u00a0the mid-19th century, the heather itself\u00a0has\u00a0been\u00a0burned in rotation (a practice known as\u00a0muirburn)\u00a0to provide\u00a0the birds with young shoots to eatand older stands for cover, giving\u00a0the hills a\u00a0distinctive\u00a0patchwork appearance.\u00a0Trees are discouraged.\u00a0Saplings that survive the flames\u00a0are grazed by sheep and deer. Historically,\u00a0predators\u00a0such as raptors, foxes and stoats\u00a0have been\u00a0trapped or shot,\u00a0and some\u00a0illegal\u00a0persecution\u00a0continues\u00a0today.<\/p>\n

They might be bonny, but Scotland\u2019s\u00a0heather-clad hillsides\u00a0are\u00a0low in biodiversity, poor at storing carbon, and prone to erosion and flooding.\u00a0They look wild,\u00a0but\u00a0they\u00a0are managed\u00a0intensively\u00a0to serve\u00a0the interests of a single species \u2013\u00a0until\u00a0the 12th of August,\u00a0at least, which is\u00a0when the shooting starts.<\/p>\n

Top image: Pavel Kirillov from St.Petersburg, Russia, CC BY-SA 2.0 https:\/\/creativecommons.org\/licenses\/by-sa\/2.0<\/a>, via Wikimedia Commons<\/p>\n","protected":false},"excerpt":{"rendered":"Indiscriminate predators,\u00a0insatiable grazers,\u00a0ecosystem engineers, flagrant opportunists and invasive horrors\u2026 here\u2019s our pick of the animals great and small…\n","protected":false},"author":2,"featured_media":211394,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[49,48,66,323],"class_list":{"0":"post-211393","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-wildlife","8":"tag-ca","9":"tag-canada","10":"tag-science","11":"tag-wildlife"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/211393","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=211393"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/211393\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/211394"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=211393"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=211393"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=211393"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}