211 Fun Facts About Ecology

Which German scientist coined the term 'ecology' (Ökologie) in 1866?

Ernst Haeckel introduced 'Ökologie' in his 1866 Generelle Morphologie der Organismen, the same book in which he pushed Darwin's ideas onto German readers.

Which artistic movement drew on the sea-creature plates of Kunstformen der Natur (Art Forms in Nature), published from 1899?

Art Nouveau: designers such as René Binet and Émile Gallé borrowed the curling shapes of its jellyfish and radiolarians, and Binet drew on the same zoologist's work for his gate to the 1900 Paris Exposition.

The word 'ecosystem' first appeared in print in 1935 in a publication by which British ecologist?

Arthur Tansley used 'ecosystem' in his 1935 paper in the journal Ecology, wanting a word that stressed the exchange of materials between organisms and their physical surroundings.

Garrett Hardin's 1968 essay about herders overstocking a shared pasture gave environmental debate which phrase?

The tragedy of the commons: each herder gains by adding one more animal while the cost of overgrazing is shared by all, so, Hardin argued, freedom in a commons brings ruin to everyone.

Which American ecologist wrote the 1953 textbook Fundamentals of Ecology with his brother?

Eugene Odum wrote it with his younger brother Howard and built the whole book around the ecosystem, which carried that word out of the journals and into common use.

Whose 1927 book Animal Ecology set out food chains, ecological niches and the 'pyramid of numbers'?

Charles Elton: such diagrams are still called Eltonian pyramids, and his 'food cycle' is what later textbooks renamed the food web.

Ecologists sort organisms into trophic levels, a term taken from the Greek trophē, meaning what?

Nourishment: a trophic level is a step in the food chain. Raymond Lindeman's 1942 paper setting the levels out was at first rejected by the journal Ecology as too theoretical.

Roughly what share of the chemical energy in its food does a consumer turn into its own tissue?

About 10%: most of the rest is lost as heat, which limits how many levels an ecosystem can support and is why food chains run out after only a few links.

Which ecological pyramid can be inverted in a pond, where phytoplankton reproduce fast but live briefly?

The pyramid of biomass: a small standing crop of fast-reproducing phytoplankton can weigh less than the zooplankton and fish that eat it, whereas energy pyramids are always upright.

Which zoologist introduced the keystone species concept in the 1960s after a starfish-removal experiment?

Robert Paine coined 'keystone species' after he removed the starfish Pisaster from a stretch of Washington shore and watched mussels crowd out most other species.

The 1960s paper that coined 'keystone species' paired the California mussel with which predator as its main example?

Ochre starfish: Pisaster ochraceus eats the mussels that would otherwise take over the rock, which leaves room for the seaweeds, sponges and anemones it does not eat.

Sea otters protect kelp forests mainly by eating which grazers?

Sea urchins: where fur hunters all but wiped the otters out, urchins multiplied unchecked and overgrazed the kelp forests.

The sea otter's fur, the densest of any animal, packs up to how many hairs per square centimetre?

150,000: that is about a million hairs per square inch, more than on a whole human head. With no blubber, the otter relies on that coat to keep warm.

In ideal conditions, giant kelp can lengthen by roughly how much in a single day?

About 50 cm: published peaks run from 45 to 60 cm a day, among the fastest growth of any organism, so a kelp forest torn up by winter storms can grow back each spring.

Which animal makes up most of the winter prey of Yellowstone's wolves?

Elk: in the decades without wolves the herds grew until young aspen and cottonwood were badly overbrowsed, and since the 1995 reintroduction elk have again been the staple of the park's packs.

Who killed Yellowstone's last known wolves, two pups, in the 1920s?

Park rangers: wiping out wolves was then government policy, and it took a change of policy to bring wolves back to the park in 1995.

Which animal's colonies multiplied in Yellowstone as streamside willows recovered from the late 1990s?

Beaver: willow is their winter food, so colonies spread as it came back; how much credit the returned wolves deserve is still argued.

The 1960 'green world hypothesis' says the planet stays green because which group keeps herbivores in check?

It flipped the prevailing bottom-up view of communities, and is often shortened to the HSS hypothesis.

Joseph Grinnell's 1917 paper, probably the first to use 'niche' in research, concerned which bird?

The California thrasher: Grinnell's 1917 paper in The Auk tied the bird to chaparral habitat, a habitat-based niche now contrasted with later functional and mathematical definitions.

G. Evelyn Hutchinson defined the niche as an 'n-dimensional' what?

An n-dimensional hypervolume: giving each condition a species needs its own axis let Hutchinson blend the older habitat and feeding ideas of the niche into one that could be measured.

The competitive exclusion principle is also known by what name?

Gause's law: the name honours a Soviet biologist whose 1930s laboratory cultures showed one species driving a rival extinct when both lived on the same food.

A classic 1930s laboratory test of competitive exclusion grew two species of which microorganism?

Paramecium: each species thrived alone, but grown together on the same food P. aurelia drove P. caudatum to extinction.

Henry Cowles's pioneering 1899 study of ecological succession was carried out on sand dunes beside which Great Lake?

Lake Michigan: Cowles, who learned Danish to read Eugen Warming's plant ecology in the original, worked on the Indiana Dunes, and his paper set off the campaign to preserve them.

In succession theory, what is the supposedly stable community at the end of a sere called?

Climax: Frederic Clements held that each region's climate fixes one stable climax, an idea challenged by ecologists who saw a far greater role for local soils and chance.

Off which country does Surtsey, the volcanic island that rose from the sea in 1963, lie?

Iceland: Surtsey was protected in 1965 while it was still erupting, so that scientists could watch plants and animals colonise brand-new land without outside interference.

Which cactus of the Sonoran Desert is called a keystone species because so many animals feed and nest in it?

Saguaro: woodpeckers and gilded flickers dig nest holes in its flesh, and when they move out, elf owls, purple martins and finches move in.

A remora riding a shark, eating scraps while the shark is unaffected, is a classic example of which interaction?

Commensalism leaves the host unchanged while the hanger-on often evolves big adaptations, like the remora's sucker disc.

When an interaction harms one species while the other is completely unaffected, it is called what?

Amensalism, as when a penicillium mould's secretions kill nearby bacteria at no cost to the mould; it sits beside competition, where both parties lose, in the grid of species interactions.

Cowbirds, whydahs and many cuckoos lay eggs in other birds' nests for the hosts to raise; what is this strategy called?

Brood parasitism goes as far as disguise: the common cuckoo's barred underparts make small birds treat it like a sparrowhawk, which buys the female time to lay.

In 1885 botanist Albert Frank argued that mycorrhizae on tree roots were doing what?

Feeding the tree: Frank proposed that the root partner draws nutrients from soil and humus and passes them to its host, which feeds it in return, a trade since confirmed.

Which forest ecologist's 1997 work revealed the mycorrhizal networks nicknamed the 'wood wide web'?

Suzanne Simard used carbon isotopes as tracers and found birch and Douglas fir passing carbon to each other underground, with firs growing in shade on the receiving end.

What lets a clownfish nestle among an anemone's stinging tentacles without being harmed?

A mucus coating: the fish's slime seems to lack the chemical cue that fires the anemone's stinging cells, though how much of it is innate and how much is picked up from the host is disputed.

What happens in an anemonefish group when the dominant breeder is lost?

The breeding male becomes female: clownfish live in a strict size ranking, so when the dominant female dies her mate changes sex and the largest non-breeder becomes the new breeding male.

Australia's cane toads all descend from roughly how many animals, shipped to Queensland in 1935?

About 100: the 102 toads from Hawaii bred so fast that thousands of their young were released into the cane fields within months, sent to eat the beetles whose grubs were killing the crop.

Cane toads, a plague across northern Australia, are native to which region?

The Americas: native to Central and South America, the toads were shipped first to Puerto Rico and then Hawaii to eat sugar-cane pests, and Australia took up the idea from there.

Zebra mussels, which invaded the Great Lakes in the 1980s, are native to which waters?

The Black and Caspian Seas: zebra mussels crossed in ships' ballast water and were first found in Lake St. Clair, between Lakes Huron and Erie, in 1988.

Kudzu was introduced to the US at the 1876 Centennial Exposition in which city?

Philadelphia: Japan's garden at the 1876 Centennial Exposition showed kudzu off as an ornamental; in the 1930s the US government handed out some 85 million seedlings to hold eroding soil.

In r/K selection theory, what does the K in the logistic growth equation stand for?

Carrying capacity: K-strategists such as elephants and whales live at densities close to that ceiling, so they raise a few well-tended young rather than flooding the world with offspring.

MacArthur and Wilson's 1967 theory of island biogeography predicts the most species on which kind of island?

Large and near the mainland: nearness brings more colonists and size lowers each species' risk of dying out, so the count settles where arrivals balance losses.

Daniel Simberloff's test of island biogeography theory fumigated small mangrove islets where?

The Florida Keys: once the islets had been fumigated to clear their insects and spiders, the team monitored the arrivals, and within a year the species counts were back at their old levels.

Rachel Carson's Silent Spring warned chiefly against the overuse of what?

Pesticides: Carson's 1962 attack on their careless use helped open the debate about pollution that led Washington to create the Environmental Protection Agency eight years later.

The title Silent Spring was inspired by a poem containing the line 'And no birds sing' by which poet?

John Keats: the line closes the first stanza of 'La Belle Dame sans Merci' (1819); 'Silent Spring' was first just the birds chapter's title before Carson's agent Marie Rodell suggested it for the book.

Which 1951 ocean bestseller won Rachel Carson a National Book Award and let her write full-time?

The Sea Around Us: on the strength of it Carson's first book, which had sold poorly a decade earlier, was republished and became a bestseller as well.

What is the process by which a persistent toxin grows more concentrated at each step up the food chain called?

Biomagnification: such poisons lodge in body fat instead of being flushed out, so each animal inherits the load of everything it eats and top consumers end up carrying the most.

Nitrogen gas makes up what percentage of Earth's atmosphere?

About 78% by volume, with oxygen at 21%; almost none of that nitrogen is usable until bacteria, lightning or the Haber-Bosch process fix it into other forms.

Symbiotic nitrogen-fixing bacteria such as Rhizobium live in the root nodules of which group of plants?

Legumes: peas, beans, clover and alfalfa house Rhizobium in root nodules, which is why farmers rotate them through tired fields to add nitrogen.

Which process closes the nitrogen cycle by turning nitrates back into nitrogen gas?

Denitrification: it is the work of bacteria that, where oxygen runs short, breathe nitrate instead and so send the nitrogen back to the atmosphere.

Which reservoir holds Earth's largest pool of actively cycled carbon, about 50 times more than the atmosphere?

The deep ocean: for all that it holds, it trades carbon with the surface only over centuries, because the thermohaline circulation that links the two layers is so slow.

Which nutrient cycle is unusual in that the atmosphere plays almost no part in it?

Phosphorus rarely forms a gas, so its cycle runs through rock, soil and water rather than the air; phosphine appears only in isolated anaerobic conditions.

Norman Myers's 1988 term for regions exceptionally rich in unique species yet under severe threat is biodiversity what?

Hotspots: to qualify, a region must also have lost at least 70% of its original vegetation, so the label marks a crisis as much as a treasure house.

The Great Barrier Reef is made up of roughly how many individual reefs?

About 3,000: they string out along some 2,300 km of the Queensland coast, and every one was built up by tiny coral polyps.

During coral bleaching, stressed corals expel which photosynthetic symbionts living in their tissue?

Zooxanthellae: these single-celled algae feed the coral through photosynthesis, so once they are expelled it turns white and, if the stress lasts, starves.

The Ramsar Convention, the 1971 treaty protecting wetlands, is named after a city in which country?

Iran: the treaty was adopted on 2 February 1971 in the northern town of Ramsar, which is why World Wetlands Day falls on that date each year.

Which region is the world's largest tropical wetland?

Pantanal: most of its floodplain goes under water in the rainy season, and that yearly flood pulse is what sustains its dense array of animal life.

Marjory Stoneman Douglas famously described which wetland as a 'River of Grass' in 1947?

The Everglades: Douglas's 1947 book The Everglades: River of Grass described its sheetflow, a broad, shallow river creeping south from Lake Okeechobee across southern Florida.

The taiga, or boreal forest, holds which record among Earth's biomes?

Largest land biome: it owes its size to geography, forming a belt of conifers right around the north of the globe, through Alaska, Canada, Scandinavia and Siberia.

Robert Whittaker's classic biome classification uses which two abiotic factors?

Precipitation and temperature: plotted against each other, the two sort the land into biomes, so a desert and a forest of the same warmth differ only in how much rain they get.

The textbook lynx and snowshoe hare population cycle came from which firm's fur records?

Hudson's Bay Company: its fur-trade ledgers, kept for business and not for science, logged each year's lynx and hare pelts and so became ecology's classic record of linked boom and bust.

The Lotka-Volterra equations are the classic model of which ecological relationship?

Predator and prey: Volterra took up the problem when his future son-in-law, a marine biologist, noticed that predatory fish made up more of the Adriatic catch after the First World War cut fishing.

Which chemist formulated the Gaia hypothesis in the 1970s with microbiologist Lynn Margulis?

James Lovelock: the idea came to him while he was working for NASA on ways to detect life on Mars, when he reasoned that living things must reshape a planet's atmosphere.

Which novelist suggested naming the Gaia hypothesis after the Greek Earth goddess?

William Golding, the Lord of the Flies author, was a fellow villager and walking companion of the hypothesis's creator in Bowerchalke, Wiltshire, and proposed the goddess's name to him.

Biosphere 2, the largest closed ecological system ever built, stands in which US state?

Arizona: it is called '2' because its builders counted Earth itself as Biosphere 1; eight people were sealed inside the glass complex at Oracle for two years from 1991.

What turned out to be quietly draining oxygen from Biosphere 2 during its first two-year closure?

Concrete soaking up CO2: soil microbes were turning oxygen into carbon dioxide, and isotope tests showed the unsealed concrete absorbing that gas, which hid where the oxygen had gone.

At deep-sea hydrothermal vents, what forms the base of the food chain in place of plants?

Chemosynthetic bacteria: they build food from the vents' hydrogen sulfide instead of sunlight, and giant tube worms, which have no mouth or gut, live by housing them inside their bodies.

Periodical cicadas of the genus Magicicada emerge en masse at intervals of how many years?

13 or 17 years: emerging in such numbers means the birds and mammals that feast on them cannot eat them all, and one hypothesis holds that prime-numbered cycles stop any enemy's own cycle from matching theirs.

The Wallace Line runs through the strait between Bali and which neighbouring island?

Lombok: the strait is narrow but deep, so when ice-age seas fell and joined Bali to mainland Asia, Lombok stayed cut off, and the animals on its two shores remain strikingly different.

Lichens are hybrid colonies: filaments of fungus living symbiotically with which other organisms?

Algae or cyanobacteria: these partners make food from sunlight for the whole colony, so a lichen feeds itself as a plant does though it has no roots.

What does the greater honeyguide eat from the bees' nests it leads honey-hunters to?

Wax: the bird eats the comb the hunters leave behind, and Mozambican honey-hunters summon it with a special call that doubles their chance of being guided.

Oxpeckers perch on rhinos and zebras eating ticks, but they also feed on what from their hosts?

Blood from wounds: oxpeckers peck at sores to keep them open and drink from them, which is why some biologists now class the birds as part parasite, not pure helper.

Which insects pollinate figs by squeezing in through a tiny pore to reach the flowers hidden inside?

Wasps: a fig is a hollow stalk lined on the inside with tiny flowers, so only a female fig wasp, crawling in through the pore at its tip to lay her eggs, can pollinate it.

Which naturalist, who climbed the Andean volcano Chimborazo in 1802, is often called the father of plant geography?

Alexander von Humboldt climbed higher on Chimborazo than any European before him, and by noting how plants changed as the air cooled he founded the idea of altitude zones.

What is the over-enrichment of a lake or sea with nutrients, which feeds algal blooms that use up its oxygen, called?

Eutrophication: fertiliser runoff and sewage feed the blooms, and as the dead algae rot, bacteria use up the dissolved oxygen that fish and other animals need.

What is the sunlit top 200 metres or so of the open ocean called?

Photic zone: beyond about 200 metres there is rarely any significant light, so this thin layer supports the vast majority of the ocean's commercial fisheries.

Which group includes the white rots, among the few organisms able to digest the lignin that makes wood tough?

Fungi: lignin resists decay better than almost any other plant material, and where brown rots eat only a tree's cellulose, white-rot fungi digest the lignin as well.

Henry Walter Bates, of Batesian mimicry, studied butterflies in the rainforests of which country?

Brazil: Bates sailed for the Amazon with Alfred Russel Wallace in 1848 and stayed eleven years, noticing there that harmless butterflies wore the warning colours of foul-tasting ones.

Tundra is divided by region into which three types?

Arctic, Alpine and Antarctic: in all three, cold and a short growing season stop forest from taking hold, whether near the poles or high on mountains anywhere in the world.

What is the ecotone between tundra and forest called?

The timberline, or tree line: beyond it cold and wind stop trees growing, and the last ones at the edge are sparse, stunted and bent by the wind.

What key feature defines a savanna's tree cover?

Trees are spaced so the canopy stays open: the gaps let enough light reach the ground to support a continuous grass layer, which is what separates savanna from closed forest.

Which type of climate shapes California's chaparral shrubland?

Mediterranean: mild wet winters grow the shrubs and hot dry summers leave them tinder-dry, so chaparral is built to burn, reseeding or resprouting from its stumps after each fire.

What stops mangroves, which grow mainly between 30° N and 30° S, from spreading further toward the poles?

Freezing temperatures: mangroves are tropical trees that frost kills, which is why the greatest area of mangrove forest lies within 5° of the equator.

Mangroves belong to several unrelated plant families that each evolved ways to survive in what?

Salt water: mangroves are not close relatives but a case of convergent evolution, each family separately evolving ways to filter out or shed salt and to breathe in airless mud.

The Valdivian temperate rainforests are found in which region?

Southwestern South America: hemmed in by the Pacific, the Andes and the Atacama Desert, Chile's Valdivian forests have a long history of isolation from the continent's tropical forests.

Why are estuaries among the most productive habitats on Earth?

Rivers and tides both deliver nutrients: river and sea meet in sheltered shallows, and that food-rich calm is why so many sea fish spend their youth in estuaries.

Which giant snake, descended from released pets, now breeds in south Florida's wetlands?

Burmese python: hard to spot despite its size, it has been linked to sharp declines in the mammals of the areas where it is established.

Which venomous, banded reef fish from the Indo-Pacific has invaded the western Atlantic and Caribbean?

Lionfish: probably dumped from home aquariums off the US coast, they spread fast because almost nothing in Atlantic waters will eat them, and they devour the young of snapper and grouper.

Which island's native birds were mostly wiped out by the brown tree snake?

Guam: the snake arrived by accident after the Second World War and emptied nearly all the island's forests of birds; with them gone, spiders spin up to 40 times as many webs there as on nearby islands.

Under what commercial name, adopted in 2022, are invasive Asian carp sold in the US?

Copi: the name was launched in June 2022 to sell the fish to the public as healthy, responsible seafood, in the hope that eating them will thin their numbers in American rivers.

Why did Thomas Austin have rabbits shipped from England to his Australian estate in 1859?

Sport hunting: Austin wanted game to shoot, and within a few years tens of thousands of rabbits had been killed around his estate; their descendants went on to overrun the continent.

Which pathogen was released in Australia in 1950 to cut rabbit numbers?

Myxoma virus: at first it killed almost every rabbit it infected, but resistant rabbits and milder strains of the virus soon evolved, and numbers climbed back.

Which Australian state finished a coast-to-coast rabbit-proof fence, some 1,800 km long, in 1907?

Western Australia: rabbits had already been found west of the line by 1902, long before the crews finished, so a second and a third fence were built behind the first.

The Nile perch's spread through Lake Victoria devastated which group of native fish?

Cichlids: Lake Victoria's haplochromine cichlids, perhaps 500 species, lost around 200 of them after the Nile perch, introduced in the 1950s, boomed through the lake in the 1980s.

Water hyacinth is anecdotally known as the 'terror' of which region?

Bengal: the South American floater earned the name 'terror of Bengal' after choking the region's waterways; its mats can double in area in a fortnight.

Which trees does the invasive beetle Agrilus planipennis, found near Detroit in 2002, kill?

Ash: the emerald ash borer, Agrilus planipennis, was detected in Michigan in 2002; its larvae tunnel under the bark and have killed tens of millions of ash trees across North America.

Which WWF founder co-created the IUCN's Red Data Books?

Peter Scott took over the IUCN's species commission in 1963 and backed the loose-leaf Red Data Books, begun in 1964, which listed animals at risk and grew into today's Red List.

Martha, the last passenger pigeon, died in 1914 at which zoo?

The Cincinnati Zoo: Martha died there on 1 September 1914, and her body was frozen into an enormous block of ice and sent to the Smithsonian to be mounted.

In which US state did a boy shoot 'Buttons', long thought the last wild passenger pigeon, in 1900?

Ohio: the bird was shot in Pike County and mounted with buttons for eyes, but later research found wild passenger pigeons shot in Illinois in 1901 and Indiana in 1902.

Which living bird is the dodo's closest relative?

The Nicobar pigeon: DNA work in 2002 tied the dodo to this iridescent Southeast Asian bird; sailors hunted it, but the pigs and rats they brought, eating eggs laid on the ground, probably did more to finish it off.

The Serengeti's wildebeest migration loops north out of Tanzania into which Kenyan reserve?

Maasai Mara: the herds follow the rains in a great circle, crossing the Mara River around July and turning back south to the Serengeti plains around October.

Which New Mexico area did Aldo Leopold propose as the Forest Service's first wilderness?

The Gila: Leopold argued that some wild country should be kept free of roads, and on 3 June 1924 the Forest Service made it the first area in the world managed as wilderness.

In which state is the shack where Aldo Leopold wrote A Sand County Almanac?

Wisconsin: the Leopolds bought a farm near Baraboo in 1935, made its old chicken coop 'the Shack', and set about planting trees and restoring prairie on the land.

The Population Bomb (1968) was published by Ballantine together with which organisation?

The Sierra Club: the book appeared as a Sierra Club–Ballantine paperback in 1968 and sold over two million copies, though co-author Anne Ehrlich went uncredited at the publisher's insistence.

Which term did Paul Ehrlich and Peter Raven popularise in a 1964 paper on butterflies and the plants they eat?

Coevolution: they argued that plants evolve new chemical defences, butterflies evolve ways round them, and each escape lets one side spread into many new species.

Which 1954 series began David Attenborough's presenting career?

Zoo Quest: Attenborough was only meant to produce it, but London Zoo curator Jack Lester fell ill after the first trip, to Sierra Leone, so he stepped in front of the camera.

In which 1979 series did David Attenborough famously come face to face with mountain gorillas in Rwanda?

Life on Earth: he had crawled close to deliver a scripted line about the opposable thumb, but when a female gorilla turned to him he dropped the script and whispered an ad lib.

In Mao's Four Pests campaign of 1958, the mass killing of which birds let crop-eating insects multiply unchecked?

Sparrows: people chased the birds until they dropped from exhaustion, but sparrows eat insects as well as grain, locusts flourished, and in 1960 bed bugs took their place on the list.

Which conditions are typically greater at habitat edges than in the interior?

Wind exposure, light and temperature fluctuations: without a closed canopy the edge is brighter, windier and swings more between day and night, which is why small fragments show such strong edge effects.

Which term did Richard Levins coin for scattered colonies linked by occasional migrants?

Metapopulation: Levins, modelling insect pests in farm fields, called it 'a population of populations', in which local patches die out and are recolonised from their neighbours.

Which Canadian province hosts the Experimental Lakes Area, famed for phosphorus research?

Ontario: in lakes near Kenora, David Schindler's 1970s whole-lake experiments pinned algal blooms on phosphorus and drove bans on phosphate detergents.

What term describes water so short of dissolved oxygen, under about 2 mg per litre, that most fish flee or die?

Hypoxic: below about 2 mg of oxygen per litre most fish swim away, and under 0.5 mg mass die-offs begin; rotting algal blooms fed by excess nutrients are the usual cause.

Runoff from which river system feeds the Gulf of Mexico's annual summer dead zone?

The Mississippi: nitrogen and phosphorus washed off Midwest farmland feed algal blooms off Louisiana each summer, and the 2017 dead zone reached a record 22,700 square kilometres.

Peruvian fishermen named the El Niño current after whom?

The Christ Child: the warm current tended to arrive off Peru around Christmas, so fishermen called it El Niño de Navidad.

What is the cooling phase of the ENSO cycle called?

La Niña, 'the girl', is the cool phase in which strong trade winds pile warm water in the west Pacific and cold upwelling chills the coast of Peru; El Niño is the warm phase.

Which discipline studies periodic events such as leaf-out and bird migration dates?

Phenology: Kyoto's cherry-blossom dates have been logged since the year 812, and in 2021 the trees peaked earlier than at any time in those 1,200 years as springs warmed.

Monarch butterflies overwinter in Mexico on which tree?

The oyamel fir: its high mountain forests hold a cool, humid microclimate, mild enough that the butterflies need not burn their fat to keep warm and damp enough that they do not dry out.

Since 1976, monarch roosting sites have been identified in which two Mexican states?

Michoacán and México: Fred Urquhart had long tracked the migration with wing tags, but the first roost was found only in January 1975, by a couple who had answered his newspaper appeal.

What is ground called once it has stayed at or below 0 °C for at least two years running?

Permafrost: two years is enough to qualify, yet the oldest has stayed frozen for some 700,000 years, and it locks away about twice as much carbon as the whole atmosphere holds.

Fish that hatch in fresh water, mature at sea and return upriver to spawn are called what?

Anadromous, from the Greek for 'running up'; Pacific salmon are the extreme case, swimming far upriver to spawn once and then dying.

Which nutrients do dead salmon carry from the ocean into forests and wetlands?

Nitrogen, sulfur, carbon and phosphorus: bears haul salmon into the woods and leave half-eaten carcasses, and nitrogen from the sea turns up in spruce needles up to 500 m from the stream.

Which principle says island colonists tend to become bigger if small and smaller if large?

Foster's rule, or the island rule, from J. Bristol Foster's 1964 study: with fewer enemies small animals can afford to grow, while scarce food on a small island favours shrinking in big ones.

Island dwarfism shrank which animals to about a metre tall on Sicily and Malta during the Ice Age?

Elephants: Sicily's Palaeoloxodon falconeri stood about a metre tall, yet its bones show it grew slowly, matured at about 15 and could live nearly 70 years, longer than its four-metre ancestor.

Bergmann's rule links larger body size to which kind of environment?

Colder: Carl Bergmann reasoned in 1847 that a bigger body has less surface for its bulk and so sheds heat more slowly, though he was not the first to spot the pattern.

Allen's rule predicts that mammals of hot climates will have noticeably larger what than their cold-climate relatives?

Ears: Joel Asaph Allen argued in 1877 that long ears, tails and limbs shed heat in hot climates while short, thick ones hold it in, which is why a polar bear's ears are so small.

What do conservationists call a charismatic animal, like the giant panda, chosen as the public face of a campaign?

Flagship species: the WWF modelled its 1961 logo on Chi Chi, a giant panda at London Zoo, partly because a black-and-white animal would stand out in cheap one-colour printing.

What term describes the productive area able to regenerate what people take from nature?

Biocapacity: the accounts weigh cropland, forest, grazing land and fishing grounds by how productive they are, and since the early 1970s humanity has demanded more each year than the planet's total.

What problem do wildlife corridors chiefly mitigate?

Habitat fragmentation: corridors such as the Banff wildlife overpasses on the Trans-Canada Highway let animals move between patches, keeping isolated populations genetically connected.

How does rewilding differ from other forms of ecological restoration?

It aims to reduce human influence on ecosystems: rather than managing toward a fixed historical baseline, rewilding restores processes such as grazing and predation and accepts the novel ecosystems that result.

Pleistocene Park aims to restore a grassland named after which animal?

Woolly mammoth: Sergey and Nikita Zimov argue that herds trampling the winter snow let the cold bite deeper into the soil, so a restored 'mammoth steppe' could help keep Arctic ground frozen.

In which forest was the last wild lowland European bison killed, shortly after the First World War?

Białowieża: the wild herd was gone within a few years of the war and the species survived only through 54 animals in zoos; bred back and released, hundreds roam the forest again.

To keep condor chicks wild, zoo keepers fed them using what?

Hand puppets: keepers fed chicks with a glove shaped like a condor's head so the birds would not imprint on people, and captive-bred condors were flying free in California again by 1992.

Since releases began in 1992, what has killed more free-flying California condors than anything else?

Lead poisoning: condors swallow fragments of lead ammunition in the carcasses and gut piles they scavenge, so wild birds are regularly recaptured to be tested and treated.

Which bird, off the US endangered list since 2007, built the largest nest ever recorded?

Bald eagle: a pair near St Petersburg, Florida, and possibly their successors, kept adding sticks until the nest, examined in 1963, was 2.9 metres wide and weighed over two tonnes.

Which North American mammal, thought extinct in 1979, turned up alive in Wyoming two years later?

Black-footed ferret: the last 18 wild animals were caught by 1987 to start a breeding programme, and the ferrets released on the prairies since all descend from that one Wyoming colony.

Which falcon vanished from eastern North America as DDT thinned its eggshells?

Peregrine falcon: the pesticide left its eggs too thin-shelled to survive, but after the ban falconers and biologists released captive-bred young, and it came off the US endangered list in 1999.

A chytrid fungus spread worldwide by trade has been linked to declines in hundreds of species of which animals?

Frogs: the fungus attacks the skin of amphibians, and a 2019 survey, since challenged, linked it to declines in at least 501 species, 90 of them presumed extinct.

In 2016, the IUCN reclassified the giant panda to which Red List category?

Vulnerable: the IUCN moved the panda down from Endangered in September 2016 after China's fourth survey counted 1,864 wild adults, a recovery it credited to restored bamboo forest.

After Sudan, the last male northern white rhino, died in 2018, the two surviving females lived under armed guard in which country?

Kenya: Najin and her daughter Fatu were guarded at Ol Pejeta Conservancy, where vets collected their eggs to be fertilised with stored sperm in a laboratory, hoping southern white rhinos could carry the embryos.

Bycatch from illegal fishing of which fish is driving the vaquita to extinction?

Totoaba: gillnets set illegally for its swim bladder, sold at high prices in China, drown vaquitas, the smallest living cetacean, and fewer than 20 were left by the 2020s.

Where does the vaquita live?

The northern Gulf of California: the vaquita has the smallest range of any whale, dolphin or porpoise, so illegal nets in that one corner of Mexico threaten every animal left.

When geologists voted down the Anthropocene in 2024, which epoch, begun about 11,700 years ago, stayed as the official present?

Holocene: the panel rejected the new epoch by a wide margin, citing its shallow sedimentary record and very recent start date, and the International Union of Geological Sciences confirmed the vote.

Which atmospheric chemist popularised the term 'Anthropocene' in 2000?

Paul Crutzen, a Nobel laureate for his work on the ozone layer, was not the first to use the word: the biologist Eugene Stoermer had used it informally since the 1980s.

Per square metre, kelp forests grow about as much new plant matter each year as which land biome?

Tropical rainforest: kelp and other algal beds match it because currents and upwelling keep bathing them in nutrients, so with reefs they yield about 0.9% of Earth's plant growth from 0.1% of its surface.

Roughly how many species of fully marine seagrasses exist?

About 60, or 72 on the fullest count: they are flowering plants whose ancestors went back into the sea 70 to 100 million years ago, and some Mediterranean Posidonia clones are thousands of years old.

Which sea is the only named one without land boundaries?

The Sargasso Sea: its edges are four ocean currents, the Gulf Stream among them, circling as the North Atlantic Gyre, and it is named for the floating Sargassum weed they trap.

Danish biologist Johannes Schmidt traced ever-smaller larvae of which fish to a breeding ground in the western Atlantic, far from European rivers?

Eels: Schmidt's Dana expeditions netted the tiniest larvae thousands of kilometres from Europe, yet a century on nobody has directly watched European eels spawn there.

Why can't the Great Pacific Garbage Patch be seen from satellites?

Its debris density is too low: the patch is mostly tiny fragments spread thinly through the water, so a boat can sail through this plastic soup and see little or no debris.

Which yachtsman claimed to discover the garbage patch after a 1997 race?

Charles Moore, sailing home through the North Pacific Gyre after the 1997 Transpac race, reported a vast stretch of floating debris, a build-up that ocean scientists had already predicted on paper.

Which two mountain ranges create most rain shadows in the western United States?

The Sierra Nevada and Cascades wring Pacific moisture out of the westerly winds, which leaves the Great Basin and Death Valley beyond them among the driest places in North America.

Krummholz, the stunted tree-line growth, is German for what?

Crooked wood: freezing winds kill the exposed shoots, so the trees survive only as bent, low mats where rocks or snow shelter them; Newfoundlanders call the same growth tuckamore.

Biological soil crusts of cyanobacteria, lichens and mosses bind the ground mainly in which kind of landscape?

Deserts and drylands: these living skins cover about 12% of Earth's land and hold loose soil in place, but once crushed underfoot they can take decades, sometimes far longer, to grow back.

Which conifer's cones are sealed with resin that only fire melts away?

Lodgepole pine: many of its cones stay sealed with resin for years until heat of about 45 °C melts them open, so a fire like Yellowstone's in 1988 sows the next forest as it burns.

Which childhood accident turned E. O. Wilson towards studying insects?

He was partly blinded while fishing: at seven he lost the sight of his right eye, and without depth vision but with one very sharp eye he took to studying the 'little things' he could hold up close.

Which 1975 E. O. Wilson book set off a furious nature-versus-nurture row?

Sociobiology: The New Synthesis (1975) argued that social behaviour, human behaviour included, has a biological basis; at a 1978 science meeting protesters who called that racist doused Wilson with water.

Which palaeontologist mentored both Jane Goodall and Dian Fossey?

Louis Leakey, who believed living apes would illuminate early hominids, sent Goodall to Gombe in 1960 and Fossey to the mountain gorillas in 1966; Biruté Galdikas followed with orangutans.

In 1960 Jane Goodall watched a chimpanzee do what, long thought uniquely human?

Make and use tools: he fished termites from a mound with grass stems, and her mentor replied that we must now redefine man, redefine tool, or accept chimpanzees as human.

Dian Fossey founded which research centre in Rwanda?

Karisoke, founded in 1967 and named for the volcanoes Karisimbi and Bisoke it sits between; Gorillas in the Mist appeared in 1983, two years before Fossey's murder there.

Which Galápagos birds, rather than the finches, first made Darwin doubt that species were fixed?

Mockingbirds: Darwin found that those shot on different islands were different species and wrote that they first 'thoroughly aroused' his attention, whereas most of his finch specimens had been mingled together.

Despite their name, DNA studies place Darwin's finches in which family of mostly tropical American songbirds?

Tanagers: their nearest living relative is the dull-coloured grassquit of South America, so the most famous finches in science are not true finches at all.

Peter and Rosemary Grant saw which Galápagos finch trait shift after a 1977 drought?

Beak size: the drought left only large, hard seeds, so birds with bigger beaks survived to breed, the most intense natural selection then measured in a wild vertebrate.

Estimates in the 2010s put extinction rates at how many times the background rate?

100 to 1,000 times higher: a 2014 review led by Stuart Pimm put current losses at about 1,000 times the natural background rate, which is why scientists speak of a sixth mass extinction.

Bullhorn acacias of Central America house and feed colonies of which insects, which attack anything that touches the tree?

Ants: the acacia offers hollow thorns to nest in, nectar and protein-rich leaf tips, and in return the ants sting browsing animals and clear away competing plants, a textbook mutualism.

Coral reefs cover under 0.1% of the ocean but shelter at least what share of sea species?

A quarter: reefs thrive in clear water that holds few nutrients, yet on an area about half the size of France they shelter at least 25% of known marine species.

Which waterlogged wetlands cover about 3% of Earth's land yet hold more carbon than all the world's forests?

Peatlands: year-round waterlogging slows the rotting of dead plants so much that carbon piles up as peat, and when bogs are drained or burned it escapes, causing almost 5% of human CO2 emissions.

Which desert is the driest place on Earth outside the polar regions?

Atacama: the Andes on one side and Chile's Coast Range on the other block moist air from both oceans, and its soil is so lifeless that instruments bound for Mars are tested there.

Which wetland in the Ganges–Brahmaputra delta is the world's largest mangrove forest?

The Sundarbans: about 10,000 square kilometres of tidal forest shared by Bangladesh and India, where tigers swim from island to island to hunt deer and wild boar.

Warder Clyde Allee first demonstrated the Allee effect in the 1930s by showing which animals survive better in larger groups?

Goldfish in a crowded tank survived better, leading Allee to argue that aggregation and cooperation can raise individual fitness.

Liebig's law of the minimum was actually first formulated by which agricultural scientist?

Carl Sprengel set out the principle in 1828, a dozen years before Liebig's 1840 book popularised the idea that growth is set by the scarcest resource, not the total available.

Liebig's law, that growth is capped by the scarcest nutrient, is usually pictured as what everyday object?

A barrel with uneven staves holds only as much water as its shortest stave allows, just as a plant grows only as far as its scarcest nutrient permits; the image is known as Liebig's barrel.

Which microscopic animals, nicknamed water bears, can survive freezing, drying out and even the vacuum of space?

Tardigrades: when their moss dries out they draw in their legs and shrivel into a dormant husk with no measurable metabolism, a state in which they have survived open space.

Which 1972 report for the Club of Rome used a computer model to warn of global collapse within a century?

The Limits to Growth: its World3 model had resource shortages or pollution ending growth if nothing changed, and a 2020 check found real-world data still tracking scenarios in which growth halts within a decade or so.

In which unit is a country's ecological footprint measured?

Global hectares: each is a hectare of world-average biological productivity, so rich cropland counts for more than thin pasture and any two countries can be compared on one scale.

What does Earth Overshoot Day mark?

Nature's yearly budget used up: Andrew Simms devised the day at the New Economics Foundation, and by the Global Footprint Network's reckoning it slid from 31 December in 1972 to 30 July in 2026.

Which shrimp-like crustacean, eaten by whales, seals and penguins, anchors the Antarctic food web?

Krill are among the most abundant animals on Earth by weight, with Antarctic swarms totalling hundreds of millions of tonnes. Crabeater seals, despite the name, eat almost nothing else.

Which sea mammal tops ocean food webs and even hunts great white sharks to eat their livers?

Orca pods have no natural enemies anywhere in the sea. They flip great whites onto their backs, which paralyses the sharks, then eat the rich liver.

On a food web diagram, each arrow leaves one organism and points to another that does what to it?

Eats it: arrows follow the food, running from the organism consumed to the one consuming it. An arrow from grass to a rabbit shows the energy stored in the grass ending up in the rabbit.

Which scavenging birds have stomach acid corrosive enough to let them eat meat laced with anthrax?

Vultures have stomach acid of about pH 1, which makes them a food web's safest clean-up crew. Some species even urinate down their legs to kill germs picked up from their meals.

Australia's 5,600 km sheep fence became a food web experiment by shutting out which top carnivore?

Dingo country now lies on one side of the fence and sheep country on the other. Kangaroos and emus are scarcer where the wild dogs roam, a sign that the hunters hold grazers down.

Which term fits an animal like the grizzly bear, which feeds on berries, moths and salmon alike?

Omnivore is the label, even though grizzlies belong to the order Carnivora. In Yellowstone they can get half their yearly calories from moths gathered on mountain slopes.

Which animals, the subject of Darwin's last science book, drag dead leaves into the soil food web?

Earthworms pull leaves into their burrows by the pointed tip, Darwin found, the easiest way to drag them. He doubted many other animals had played so important a part in the world's history.

Which process in plants and plankton captures the sunlight that powers almost every food web?

Photosynthesis stores the Sun's energy as sugar, the fuel every other member of the web depends on. As a by-product it also keeps the atmosphere stocked with oxygen.

The collapse of which fish off Newfoundland let shrimp and crab take over the local food web?

Cod numbers fell to about 1% of historic levels by 1992, and Canada shut a fishery that had lasted 500 years. With the big hunter gone, the crab and shrimp it once ate boomed.

Which name covers tiny drifting sea animals, such as copepods, that graze on microscopic plant life?

Zooplankton rise toward the surface each night to feed and sink again by day. Measured by weight, that daily commute is the largest synchronised migration on Earth.

Which African mammal grazes on land by night, then feeds river food webs with its droppings by day?

Hippopotamus herds carry grass from the plains into the river as waste, feeding fish and small river animals. In large amounts, though, it can use up the water's oxygen and kill them.

What is the 'whale fall' that deep-sea biologists say can feed a seabed community for decades?

A sunken carcass delivers as much food at once as the mud beneath it would normally receive in about 2,000 years. Specialists such as bone-boring worms then feed on the skeleton for decades.

What do oceanographers call the steady shower of dead plankton and waste feeding deep-sea food webs?

Marine snow flakes can grow to several centimetres across and sink for weeks before reaching the animals waiting on the seabed. Most of it is eaten on the way down.

Which type of food web, paired with most grazing ones, is built on dead leaves and droppings?

Detrital webs carry more traffic than most people guess. On land, far more plant material is broken down after it dies than is ever eaten alive by grazing animals.

Whale faeces boost Southern Ocean food webs by returning which scarce metal to surface plankton?

Iron is so scarce in the Southern Ocean that plankton growth stalls without it. Whale faeces hold up to 10 million times more of the metal than the surrounding seawater.

The cattle plague rinderpest reshaped the Serengeti food web by killing off which antelope's herds?

Wildebeest losses left the plains to burn in intense wildfires every year. After vaccination beat the disease, the herds came back and the trees returned with them.

On which Lake Superior island have scientists tracked a simple wolf-and-moose food web since 1958?

Isle Royale gives its wolves one main quarry and its moose one main enemy, making it the longest-running study of its kind. The two populations never settled into balance and still swing wildly.

A 1999 study found songbirds persisting in suburban scrub wherever which carnivore kept cats scarce?

Coyotes turned out to be the songbirds' unlikely bodyguards. Where the big canines vanished, cats and other small hunters multiplied and the scrub-nesting birds disappeared.

Which often-overlooked group of organisms is involved in about 75% of all food web links?

Parasites are left out of most food web diagrams, yet nearly every animal carries several kinds. Drawn in properly, they would sit above even the top carnivores.

Puffin chicks starve in years when which slender fish, their staple in Shetland, runs short?

Sand eels normally make up at least 90% of the food Shetland puffins bring their chicks. A parent can catch several in one dive, pinning each against its beak with a grooved tongue.

A 2013 study ranked which species at 2.21 on the food chain, level with pigs and anchovies?

Humans eat so many plants that their average rank sits far below a top carnivore's. On the same scale a plant scores 1, a pure plant-eater such as a cow scores 2, and the fiercest hunters reach 4 or 5.

Which plant, native only to the Carolinas, flips the food chain by trapping and eating insects?

Venus flytrap leaves count before they bite: a trap shuts only when two trigger hairs are touched within about 20 seconds. That stops it wasting effort on raindrops.

Most of the energy a rabbit eats never reaches the fox that catches it, escaping mainly as what?

Heat leaks away at every step as animals burn food just to stay alive. That steady drain is why food chains rarely run past five or six links.

A caterpillar that eats oak leaves and is later eaten by a robin fills which food chain role?

Primary consumer is the role of any animal that feeds directly on plants. The robin, one step up, is a secondary consumer, and a hawk that caught the robin would be a tertiary one.

Minamata disease struck a Japanese town when which metal in factory waste moved up the food chain?

Mercury from the factory concentrated in the bay's fish and shellfish, then in the people who ate them. Local cats were struck so badly that the illness was nicknamed dancing cat fever.

Polar bear liver is toxic because which nutrient builds up along the food chain from fish to seal?

Vitamin A is stored in the liver, so each hunter inherits the load its last meal carried. By the top of the chain, one serving of liver holds a dangerous overdose for a person.

Monarch butterflies taste foul to birds because their caterpillars store toxins from which plant?

Milkweed is the only food monarch caterpillars eat, and they keep its heart-stopping poisons in their bodies. The bright orange wings warn birds of the foul taste.

Students tracing food chains often dissect which compact masses of fur and bone that owls cough up?

Pellets hold the bones an owl cannot digest, so pulling one apart shows exactly what it ate. Scientists use them to study a bird's diet without harming the bird.

Which Arctic rodents boom and crash roughly every four years, at times sending snowy owls far south?

Lemmings are the link Arctic hunters depend on, so their numbers ripple up the chain. The old tale that they leap off cliffs was staged for a 1958 Disney documentary.

Which Antarctic hunter sits near the top of the food chain, ambushing penguins at the ice edge?

Leopard seal teeth do double duty: long canines for seizing penguins, and back teeth that lock together to sieve tiny crustaceans from the water.

Which raptor sits at the end of an aquatic food chain, with live fish making up 99% of its diet?

Osprey feet are built for the job: an outer toe swings backwards so two toes grip each side of a slippery fish. The bird can also shut its nostrils as it plunges in.

Flamingos hatch greyish, then turn pink as which pigments pass up the food chain from plankton?

Carotenoids are the same pigments that colour carrots, pumpkins and egg yolks. Zoo flamingos fade to pale pink unless their feed is topped up with them.

Many cave food chains begin not with plants but with which rich deposit left by roosting bats?

Guano supports cave communities of microbes, invertebrates and even vertebrates that never see daylight. If the bats abandon a cave, the species living on their droppings can die out.

Which sea turtle, the largest of all, lives on a food chain link few animals want: jellyfish?

Leatherback turtles cross whole oceans for jellyfish, some swimming about 6,000 miles across the Pacific to reach them. Floating plastic bags look so like their food that many adults have swallowed them.

What do biologists call organisms that start a food chain by making their own food from sunlight?

Autotrophs include every green plant and seaweed, which is why they are also called producers. Everything else alive, from mushrooms to tigers, must eat them or eat something that did.

What dark, crumbly material is left in soil once decomposers finish with dead plants and animals?

Humus is simply the Latin word for earth. It can hold up to 90% of its own weight in water, which helps the plants that start the next food chain survive drought.

Poison dart frogs bred in captivity are harmless because wild ones get their toxins by eating what?

Ants and mites carry the alkaloids that wild frogs store and reuse as their own defence. Feed a captive frog the right diet and it turns poisonous again.

Which insects did Australia import from the 1960s to rescue its cattle pastures?

Dung beetles native to Australia evolved with the small, dry droppings of kangaroos, not the wet dung of cattle. Left unburied, it smothered pasture for months and bred swarms of flies.

The earliest known account of a food chain is in a medieval 'Book of Animals' in which language?

Arabic was the language of al-Jahiz of Basra, who described mosquitoes feeding on larger animals, flies hunting the mosquitoes, and other hunters eating the flies.

Sperm whales dive over a kilometre deep mainly to hunt which animals of the deep-sea food web?

Squid have hard beaks that a sperm whale cannot digest, and as many as 18,000 have been found in one stomach. Ambergris, prized by perfumers, forms around the beaks that slip further down.