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 Drafts and withdrawn editions are never mixed into this index.
Each segment is a hollow keratin shell left behind at a moult, interlocking loosely with the one before it. The rattle records moults, not years, and segments break off routinely, so counting them says nothing about the snake's age.
Its seasonal moult from brown to white is triggered by changing day length, not by snow. As snow arrives later and melts earlier, hares increasingly spend days conspicuously white on brown ground, a mismatch that raises their mortality.
Nineteenth-century naturalists described solitary male coatis as a different species from the social bands of females and young. The name coatimundi survives from that error, and both are the same animal at different life stages.
Madagascar's elephant birds weighed several hundred kilograms. Ancient DNA showed their nearest living relatives are not the ostriches of nearby Africa but New Zealand's kiwi, small nocturnal birds on the far side of the Indian Ocean.
The simplest way to separate a damselfly from a dragonfly is the resting posture. Damselflies bring their wings together over the back, while dragonflies hold theirs out flat, and the difference reflects wing shape and musculature rather than a behavioural choice.
Rather than individual nests, colonies of sociable weavers construct a single haystack-like mass of sticks containing dozens of separate chambers. The structures are maintained continuously and some have been in use for a century or more.
Sailfish are routinely called the fastest fish in the sea at around 110 kilometres per hour, but that figure traces to old line-stripping trials, and careful measurements of attacking sailfish give far lower speeds.
The metre-long transparent ribbon is a ctenophore whose body has been extended enormously along one axis and compressed along another. Four of its eight comb rows run the length of the upper edge, so the shimmer travels the animal's whole length.
The blue cap looks the same on both sexes to a human eye. Under ultraviolet, which birds can see and humans cannot, males are markedly brighter, and that hidden difference influences how blue tits choose partners.
Footage from remotely operated vehicles has shown the pelican eel inflating its huge pouched mouth until the head swells far beyond the width of its body, then deflating back to a slim eel shape.
Penguins are associated with cold southern seas, but the Galapagos penguin lives at the equator, with part of its small breeding population on the northern side of it. Cold upwelling currents, not latitude, make that possible.
Molecular and morphological evidence place the monito del monte in Australidelphia, the group containing Australia's marsupials, rather than with the American opossums it lives among. It is the sole survivor of an order that once spanned Antarctica.
The Burmese python is listed as Vulnerable in its native Asian range while an introduced population in Florida has become one of the most damaging invasive predators in North America. Conservation status describes a species where it belongs, not everywhere it lives.
On land a kangaroo's hind legs swing together, and it alternates them only in water. Tree-kangaroos, descended from those ground-dwellers, have re-evolved independent hind-limb movement on land, which is what lets them walk along a narrow branch.
After a female deposits eggs on a gravel nest a male smallmouth has excavated, she leaves. He remains, fanning the eggs and driving off intruders through hatching and beyond, often eating little for the duration of the guarding period.
These crows do not merely use sticks. They cut and shape twigs into tools with a deliberate hook at the working end, and hooked tools extract prey several times faster than straight ones in the same crevice.
Several Indo-Pacific nudibranchs share almost identical bold striping with polyclad flatworms living on the same reefs. Both groups are chemically defended, so the resemblance is usually read as mutual mimicry rather than one group copying the other.
The story that daddy long-legs carry the deadliest venom but cannot bite through skin fails twice over. Three different animals share the name, and no evidence supports exceptional potency in any of them.
The scarlet and blue skin on an adult male mandrill's muzzle is not fixed decoration. Its intensity rises and falls with testosterone and social standing, so a male who loses his position fades, and the colour signals status to rivals and females alike.
Edible-nest swiftlets navigate lightless cave interiors using bursts of clicks, one of very few bird groups known to echolocate. Unlike bat calls, the clicks fall within the range of human hearing, and their resolution is comparatively coarse.
Underwater footage of pelagic threshers confirmed a long-suspected behaviour: the shark swims into a bait ball, brakes with its pectoral fins, and slams the elongated upper tail lobe overhead fast enough to stun several fish at once.
A housefly has no jaws at all. It lands on solid food, floods it with saliva and regurgitated crop fluid, waits while the mixture dissolves, then mops up the solution through a spongy pad. A fly that walks over a meal has usually also drunk from it.
The advice to burn or salt an attached leech is worse than useless. A leech has no barbed mouthparts to break off, and irritating one makes it more likely to regurgitate gut contents into the wound.
Female Indian pythons coil around their clutch and contract their muscles in rapid twitches, raising body temperature several degrees above the surrounding air. It is one of the few clear cases of heat production by a snake.