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 Drafts and withdrawn editions are never mixed into this index.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 thick spine is a single crystal of calcite, a mineral that normally cleaves along flat planes. Its internal architecture of struts and layers arrests cracks, so the spine crumbles locally rather than splitting apart.
The first pair of legs in a tailless whip scorpion is not used for walking. Each is drawn into a whip up to several times body length, packed with chemical and mechanical sensors, and swept ahead of the animal to read a pitch-dark world.
Jackdaws are almost alone among corvids in having a strikingly pale iris. Experiments with model eyes at nest holes indicate the bright iris deters other jackdaws from entering an occupied cavity, in a species where nest sites are scarce.
The young fish is dark blue with concentric white rings, a pattern so unlike the striped adult that the two were once described as separate species. The transformation takes place gradually over roughly two years.
Eunice aphroditois lies concealed in sediment with five antennae above the surface. When prey brushes them it strikes upward and closes toothed jaws, sometimes cutting small fish, then withdraws the animal into its burrow.
Customs and police confiscations of Indian star tortoises have repeatedly involved thousands of animals in a single case. The scale of that trade led CITES to move the species to Appendix I in 2019, banning commercial international trade outright.
The population bottomed out at 22 birds in 1982. By April 1987 the last wild condor had been trapped, leaving 27 in captivity, and every condor alive today descends from that group. Lead poisoning remains the main cause of death.
True sea snakes have become so specialised that they cannot move on land. Sea kraits kept the ability. They hunt eels underwater, then haul out on rocks and islands to digest, shed their skin, drink fresh water and lay eggs.
Most European songbird species leave the singing to males. The European robin does not: females defend their own winter territories and advertise them with song, which is why robin song carries through the coldest, quietest months.
Bombyx mori exists nowhere in the wild. Millennia of selection for silk yield left adults with wings too weak to lift them and larvae that will not disperse to find food, making it one of the most thoroughly domesticated animals.
A single gopher tortoise burrow can run more than ten metres and drop several metres below the surface, holding steady temperature and humidity. Well over three hundred other animal species have been recorded using these tunnels, which is why the tortoise is called a keystone species.
Shown a Madagascan orchid with a nectar tube nearly 30 centimetres long, Darwin argued in 1862 that a moth with a matching proboscis must exist. One was described in 1903, and it was filmed feeding at the orchid only in 1992.
A caracal can spring from a standstill to strike birds flushing from cover, sometimes knocking down more than one in a leap. The story that Indian and Persian courts wagered on this is often told as the origin of the phrase to put a cat among the pigeons, but it is unverified.
The nightjar's genus name Caprimulgus means goat-milker, from an ancient belief that the birds drained livestock at night. They were feeding on insects disturbed by the animals, and the misreading has been embedded in the scientific name ever since.
Eastern and western meadowlarks overlap across the central plains and can be nearly indistinguishable in the hand. They are treated as separate species largely because their songs differ sharply and the birds themselves respond to that difference.
A displaying male skylark climbs to a hundred metres or more and sings without pause while hovering, sometimes for several minutes at a stretch. The song is a near-unbroken stream of trills, sustained by snatched breaths taken in the gaps between phrases.
Turaco feathers contain turacin and turacoverdin, copper-based pigments. The red turacin is known from no other bird; a turacoverdin-like green has since been reported in a few unrelated species. Almost all other green birds make green from structure and yellow pigment, not a green pigment at all.
The frenzy myth has the logic backwards. Experimental work indicates that red-bellied piranhas gather in shoals mainly because grouping reduces each individual's risk from larger predators, rather than because a crowd is needed to bring down prey.
It begins life with five arms, like most sea stars, and adds more throughout its life until an adult may carry two dozen. The extra arms are grown, not regenerated, and the count is a rough guide to age.
Lorikeets have papillae at the tongue tip that erect into a fringe when feeding, sweeping nectar and pollen from blossom. It is a specialisation that sets the whole subfamily apart from seed-eating parrots.
Feathers on the displaying male's cape reflect as little as a small fraction of one percent of visible light, a super-black produced by feather microstructure rather than pigment, which makes the adjacent blue shield look almost luminous.
Almost every other bird carries its nostrils near the base of the bill. The kiwi's sit at the very tip, letting it sniff out earthworms and grubs underground, and giving it a sense of smell exceptional among birds.
A female known only as Number 16 was monitored in the same Western Australian burrow from 1974 until 2016, when a parasitic wasp ended a life span longer than any recorded for a spider.
No male of this species has ever been found. It reproduces by parthenogenesis, each female producing daughters that are clones of herself, and a single animal carried in a plant pot can found a population anywhere warm.