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 Drafts and withdrawn editions are never mixed into this index.
Cornered Texas horned lizards can rupture vessels in a sinus near the eye and project a jet of blood up to a metre or more. The defence is aimed mainly at foxes, coyotes and dogs, whose reaction suggests the blood carries a compound they find foul.
Before a pack moves off, its members greet each other in an excited rally, and audible sneezes punctuate it. Observers in Botswana found that the more sneezes recorded, the more likely the rally was to end in a departure.
The desert locust has two forms so different that they were once described as separate species. The switch is triggered by physical contact, specifically repeated touching of the hind legs, and can begin within hours of crowding.
A robin cocking its head at the lawn is often described as looking, not listening. Aviary experiments point the other way: robins found buried prey with visual, olfactory and vibrational cues removed, and their success fell when white noise masked the sound.
The Atlantic striped bass fishery crashed in the early 1980s. Coordinated state moratoria and coastwide rules under a federal backstop rebuilt the stock within about a decade, making it one of the clearest cases of a deliberate fishery recovery.
The reason a cockroach is hard to swat is that it does not wait to see the threat. Wind-sensitive hairs on two rear appendages detect the air pushed ahead of a moving object, and the escape turn begins in a few tens of milliseconds.
One of the world's most widespread birds has collapsed in several European capitals. London's house sparrow population fell by the large majority over recent decades, and comparable declines were recorded in other cities while rural populations held up better.
Records for the largest moth depend on what is measured. The white witch wins on wingspan and the atlas moth is often cited by name, but by total wing surface the hercules moth of New Guinea and Queensland leads.
Muscle alone cannot contract fast enough to produce a grasshopper's take-off. The insect first co-contracts opposing muscles to bend a pad of resilin and cuticle in the hind leg, then releases the catch, so the energy comes out far faster than it went in.
Red touches yellow separates the eastern coral snake from its harmless mimics reliably enough in the southeastern United States. Applied to Central or South American coral snakes, the same rule misidentifies species with dangerous venom.
Brazilian researchers found that venom peptides from a Bothrops lancehead blocked an enzyme in the body's blood pressure pathway. That observation led to captopril, the first ACE inhibitor and the template for a class of drugs taken by millions.
The South Island takahe was written off as extinct at the end of the nineteenth century, known from a handful of specimens. In 1948 a physician tracked a surviving population to a remote Fiordland valley, and the species has been intensively managed ever since.
The copperhead is responsible for more venomous snakebites than any other snake in the United States, yet deaths are exceptionally rare. Its venom is comparatively mild and it frequently delivers little or none.
A sengi keeps a network of pathways swept clear of leaves and grit, patrols them by day, and uses them to escape at speed. An obstructed trail is a hazard, so trail maintenance is a routine part of the animal's day.
The three-second goldfish memory is folklore. Laboratory and classroom experiments have shown goldfish learning to press levers, navigate mazes and respond to feeding cues, and retaining those associations for weeks to several months.
Odontomachus mandibles close in well under a millisecond at speeds above 35 metres per second. Aimed at the ground, the same strike throws the ant several centimetres into the air, an escape reflex rather than an attack.
A drumming ruffed grouse stands on a log and beats its wings rapidly against the air. The thumping sound comes from momentary vacuums created by the wingbeats, not from the bird striking the log or its own body.
One ear opening is higher than the other, so a sound arriving from above or below reaches them with slightly different intensity and timing. That asymmetry lets a barn owl fix prey in two dimensions and strike accurately in complete darkness.
Rather than swallowing coral, the sea star pushes its stomach out through its mouth, spreads it over the colony surface, and dissolves the living tissue in place. What is left behind is a clean white scar of bare skeleton.
Bat detectors in the 1980s picked up pipistrelles calling at two clearly separated frequencies. What looked like variation in one species proved to be two, differing in genetics, roost choice and social calls but barely distinguishable by eye.
The yaks familiar from Himalayan photographs are the domestic form, bred smaller. A wild bull can stand about two metres at the shoulder and approach a tonne, roughly double the weight of a large domestic bull and considerably more against a domestic cow.
A marmot family plugs its winter burrow and hibernates together for six to eight months, arousing in loose synchrony. Older non-breeding offspring warm the pups during those arousals, so the young survive winters they could not survive alone.
At under two grams, this shrew loses heat so fast that it must run its body at an extreme rate. Heart rates as high as about 1,500 beats a minute have been recorded, the fastest measured in any mammal.
Unlike frog tadpoles, common toad larvae carry unpalatable skin compounds. This lets the species breed in deeper, fish-holding ponds where frogspawn would be eaten, and explains the different ponds the two use.