Field notebook
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Field notebook
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Permanent editions
Published facts keep their original date, evidence and correction trail. Drafts and withdrawn editions are never mixed into this index.
Unlike its stalked relatives, a feather star grips the substrate with claw-like cirri it can release at will. Once free, it swims by beating its arms in alternating sets, which is unusual behaviour for an echinoderm.
Most mammal orders contain dozens or hundreds of living species. Tubulidentata contains exactly one: the aardvark. Every other branch of that lineage has died out, leaving a single animal to represent a whole order of mammals.
A ten-gram bird loses heat fast. In hard winter weather, Eurasian wrens abandon their usual solitary habits and pile into a single roost hole, with counts of dozens of birds in one cavity on record.
Before hibernating, Helix pomatia withdraws into its shell and secretes a thick calcareous plug, the epiphragm, across the opening. It is a purpose-built winter door, discarded in spring, and it takes hours to construct.
In 1984 researchers recovered and sequenced fragments of DNA from a quagga museum skin, the first time genetic material had been read from an extinct animal. The result showed the quagga was not a separate species but a subspecies of the plains zebra.
Magicicada emerge after either thirteen or seventeen years underground, never twelve or fifteen. Both intervals are prime numbers, and both broods emerge in densities so extreme that predators cannot eat their way through the cohort.
Those enormous ears carry a dense network of blood vessels close to the surface. By dilating them in shade and shunting warm blood through the thin skin, a jackrabbit dumps heat to the air and to the cool sky without spending any water on sweating.
Donkeys tolerate dehydration that would kill a horse, then replace the deficit in a single long drink. The capacity comes from a gut that stores water and from blood that stays fluid while tissue water is drawn down.
In flight the Eurasian spoonbill holds its neck fully extended, unlike a heron or egret, which folds the neck back into an S over the shoulders. The difference is anatomical and reliable enough to identify a distant white bird by silhouette alone.
The best-supported explanation for zebra stripes is not camouflage or predator confusion. Field experiments show that horseflies approach striped surfaces as readily as plain ones but fail to land properly on them.
A moose will submerge completely to crop pondweed rooted metres below the surface. The plants carry little energy, but they are loaded with sodium, a mineral that the surrounding boreal forest almost entirely fails to supply.
Most mammals synthesise their own ascorbic acid. Guinea pigs, humans, other primates and a few scattered species cannot, because of independent losses of the same enzyme, and a deprived guinea pig develops scurvy.
A skeletal variant reducing lumbar vertebrae from six to five, and sometimes altering rib and tail vertebra counts, appears at elevated frequency in Arabian horses. It is a breed tendency rather than a defining trait, and many purebred Arabians have the standard count.
Adult workers cannot produce silk. To sew a nest they hold a mature larva in their mandibles and move it back and forth across the leaf edges, squeezing out silk that adult ants cannot make themselves.
Sea snakes almost never bite swimmers. The overwhelming majority of serious envenomations occur when a fisher sorts a catch by hand and a snake hauled up with the fish is handled, trodden on or unhooked.
Most birds have modest olfaction, but the turkey vulture detects the gas ethyl mercaptan released by early decay. It can locate carcasses under forest canopy that a soaring bird could not possibly see, and gas engineers have used the behaviour to find pipeline leaks.
Short, rounded wings and a long rudder-like tail make the goshawk slower in level flight than a falcon but far more manoeuvrable. It hunts by bursting from cover and threading between trunks, accepting frequent failure for surprise.
Shark skeletons are cartilage and rarely fossilise, so megalodon is reconstructed from teeth and a handful of vertebral columns. Its length, diet and even its family placement are inferences, and the popular figure of twenty-five metres exceeds what the evidence supports.
Transparency alone would not hide a wing, because smooth surfaces still catch the light. The glasswing's clear panels carry irregular waxy nanopillars that suppress reflection across angles, which is why the wing does not glint as it turns.
The Canada goose is a symbol of migration, yet large numbers no longer migrate. Resident flocks, seeded partly by mid-century restoration releases, now live year-round on the mown lawns and ice-free ponds that cities supply.
Females have no wings and run over sand like large furry ants, which is where the name came from. The nickname cow killer describes the sting's pain, not any recorded death of livestock.
A breeding pair holds a territory together, often for life, and yearlings from the previous litter frequently stay on to guard and feed the new pups. Litters with helpers survive at measurably higher rates than those without.
Saguaro and organ pipe cactus blooms open after dark, smell faintly of rotting fruit and hold nectar deep in a sturdy tube. Those are traits shaped by bat pollinators, and the lesser long-nosed bat is the one they were shaped for.
Each spring the great majority of North America's sandhill cranes funnel into a short stretch of the Platte River in Nebraska. They spend weeks feeding on waste grain to build fat for the flight north, then leave almost at once.