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 Drafts and withdrawn editions are never mixed into this index.
Helmeted guineafowl are sold to smallholders as a living tick-control system. They do eat ticks, along with a great deal else, but the field evidence that a flock meaningfully reduces tick numbers on a property is much thinner than the marketing suggests.
On open sand with no shelter, the mimic octopus adopts postures resembling flatfish, sea snakes and lionfish. It is one of the few animals credibly documented switching between several different impersonations.
Trained sheep distinguish and remember the faces of other sheep and of humans, retaining the associations for years. In one study they identified photographs of celebrities they had learned, and still picked out familiar faces shown at an angle.
Adult Japanese fire-bellied newts can regenerate a removed eye lens from the iris. In one long-running experiment the same individuals regrew lenses eighteen times over sixteen years, and the final lenses were as good as the originals.
The drooping face that made the blobfish famous is not how the animal looks in its own habitat. It is the appearance of a low-density deep-water fish that has been brought up through more than a kilometre of decompression.
Biomechanical modelling shows the sabre-toothed cat's jaw muscles produced less force than a modern lion's. Its long canines were fragile in a struggle, so the killing method depended on massively powerful forelimbs pinning prey first.
Glaucus atlanticus swallows air into a stomach sac to stay buoyant, drifting with its foot uppermost. Because it is upside down, its camouflage is reversed: the blue side faces the sky and the silver side faces down.
Pink salmon complete their lives in almost exactly two years. Because of that rigid clock, the fish spawning in odd years and those spawning in even years form genetically separate lineages that share a river but never share a generation.
A female Ichthyophis lays her clutch in a burrow near water and then wraps her body around it, staying with the eggs until they hatch. It was among the first parental care ever recorded in a caecilian, a group otherwise very poorly observed.
The call begins as a sequence of creaking or croaking notes, accelerates, and ends in a series of piercing shrieks audible across a wide stretch of forest. It is a nightly landmark for people living near West African rainforest.
Age estimates from otoliths and from radiometric dating agree that orange roughy live well over a century and do not spawn until their twenties or thirties, which makes a fished population very slow to recover.
Rays swim in two distinct ways. Bottom-dwelling stingrays send a wave down the edge of the disc, while eagle rays and mantas beat the whole wing up and down, which is what allows them to cover open water.
Dwarf crocodiles are among the most heavily hunted crocodilians in Africa, taken not for hides but for food. Their small size means they are often kept alive, bound, for days in markets, which makes the trade hard to quantify from carcass counts.
The boll weevil devastated American cotton after 1892. In 1919 the town of Enterprise, Alabama, erected a statue honouring the insect, because ruined cotton had forced a switch to peanuts and other crops that paid better.
Hundreds of described species, examined for well over a century, have produced no male specimen and no evidence of conventional sex. They reproduce from unfertilised eggs, and yet they have diversified rather than stagnating.
Exendin-4, isolated from Gila monster venom in the early 1990s, mimics the human hormone GLP-1 but resists the enzyme that clears it within minutes. A synthetic version, exenatide, was approved in 2005 and founded the GLP-1 agonist drug class.
A vampire bat that fails to feed for two nights running is close to starving. Roostmates regurgitate part of their own meal to keep it alive, and the sharing follows a pattern closer to friendship than to family obligation.
Porphyrin pigments in fresh flight feathers fluoresce magenta under ultraviolet light and break down with sun exposure. Banders use the pattern of glow across the underwing to estimate a bird's age, because new and retained feathers fluoresce differently.
Between the late 1970s and the 1990s the western Alaskan Steller sea lion population fell by roughly 80 per cent, while the eastern population increased. The two trends running in opposite directions is what made the cause so hard to identify.
Startled Arctic hares have been filmed rearing up and bounding on their hind legs alone, upright and kangaroo-like, for stretches of open tundra. It is a genuine gait rather than a trick of the footage, though why they use it is not established.
A foraging wood turtle stamps its front feet, or rocks and thumps its plastron, against damp soil. Earthworms below respond by surfacing, apparently reading the vibration as a burrowing mole, and the turtle simply picks them up.
After spring rain a desert tortoise drinks heavily and holds the surplus as dilute urine, a reserve it can reabsorb through months without water. Startling one into emptying that bladder can cost it the reserve it needs to survive the summer.
It is a siphonophore: a single floating unit built from many specialised zooids that cannot live apart. The float, the fishing tentacles, the digestive polyps and the reproductive bodies are separate individuals bound into one working animal.
Flamingos hatch grey and turn pink only by eating. Carotenoid pigments in the algae and brine shrimp they filter from saline water are absorbed, modified in the liver, and deposited into growing feathers, skin and bill.