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 Drafts and withdrawn editions are never mixed into this index.
The piercing cry played over soaring bald eagles in films and advertisements is almost always a red-tailed hawk. The eagle's own voice is a thin, chattering series of high whistles that sound closer to a gull than to a predator.
Thermal imaging showed that a toco toucan can shed a large share of its body heat through the bill by adjusting blood flow, dumping heat when hot and shutting the vessels down at night.
A blue-tongued skink's threat display is not just blue to human eyes. Spectrometry shows the rear of the tongue reflects ultraviolet strongly, and the animal reveals that most vivid rear portion only in the final moments of an encounter with a predator.
The word sardine covers many small clupeid fishes rather than one animal. In Europe it usually means Sardina pilchardus, the same fish sold as pilchard when it is large, but tins elsewhere may hold sprat, round herring or a Sardinops species.
The megamouth shark entered science by accident, tangled in a US Navy vessel's sea anchor off Oahu in November 1976. It was so unlike anything described that it required a new genus and a new family, not merely a new species.
A colony of snapping shrimp produces a continuous crackle loud enough to mask sonar returns. During the Second World War, submarines are reported to have sheltered near shrimp beds because the noise degraded the detection equipment hunting them.
Flying foxes are the exception to the assumption that bats find their way by echo. Pteropus species have large forward-facing eyes and excellent low-light vision, and lack the laryngeal echolocation that defines most of the order.
What was long treated as a single circumtropical ray is now recognised as at least three species separated by ocean basin. The name Aetobatus narinari was retained for the Atlantic animal, leaving decades of Indo-Pacific literature filed under the wrong species.
One queen breeds and everyone else digs, forages or defends. This division of labour, called eusociality, is common in insects and vanishingly rare in mammals, and the naked mole-rat was the first mammal shown to live this way.
The common octopus has roughly half a billion neurons, but only about a third of them are in the central brain. The majority lie in the arms, where nerve cords let each limb process touch and taste locally.
A mature greater kudu bull carries spiralled horns that typically complete around two and a half twists. Measured along the spiral they can exceed a metre and a half, but the animal moves through thick bush by tilting its head back along its spine.
It can identify a prey item and swallow it in well under a quarter of a second. The twenty-two tentacles around its nose are a touch organ dense with mechanoreceptors, and they let the animal decide edibility almost as fast as its nervous system can respond.
The long pink sac hanging from a marabou stork's neck looks like a pelican's fishing pouch but connects to the left nostril, not the gullet. It is inflated in display and thermoregulation, and deflates when the bird is calm.
Bagheera kiplingi lives on ant-defended acacias and steals the Beltian bodies the tree produces to feed its ant guards. In Mexican populations plant material accounts for roughly nine-tenths of the diet.
Male eastern tiger swallowtails are always yellow. Females come in two forms, and the dark one closely resembles the toxic pipevine swallowtail, a resemblance that appears to buy protection where the model butterfly is common.
In crowded ponds, a fraction of tiger salamander larvae develop wider heads and enlarged teeth and begin eating their pondmates. The switch is triggered by conditions rather than fixed at fertilisation, and cannibals avoid eating close relatives.
Ridges of enlarged, hooked denticles run over the eyes and down the back of this ray, unusual armour among batoids. Beneath them sit ridged tooth plates built for grinding open crabs and molluscs.
A six-week survey of the Yangtze in 2006 covering the species' entire historic range found no baiji. It was the first cetacean species to be lost through human activity, and it disappeared without a single deliberate hunting programme against it.
Rival males rub scent from wrist and shoulder glands onto their striped tails, then arch the tail forward over the back and flick it towards an opponent. Contests are settled by odour and persistence, and one animal eventually retreats.
House dust mites take no liquid water. They absorb water vapour directly from the air using a salt solution secreted by glands in the mouth region, which means humidity, not cleaning, is the variable that decides whether a population survives.
In an environment where prey arrives unpredictably with floodwater, the olm has traded speed for endurance. It lowers its metabolism, absorbs its own tissue reserves, and has been kept in laboratory conditions through fasts measured in years.
The defensive jet reaches about 100 degrees Celsius, hot enough to be widely described as boiling. High-speed imaging showed it is not a continuous stream but hundreds of separate pulses per second.
Goats have horizontally elongated pupils that give a panoramic band of sharp vision. When the animal lowers its head to feed, the eye rotates within the socket so the slit stays aligned with the horizon.
A piping plover lays four speckled eggs in a shallow scrape of open sand, sometimes lined with pebbles or shell fragments. The camouflage is so effective against predators that the main risk from people is being stepped on rather than being hunted.