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 Drafts and withdrawn editions are never mixed into this index.
A breeding male clears a rock patch and cultivates specific red algae on it, weeding out unwanted species by hand, or rather by mouth. Females inspect the resulting turf before choosing where to deposit eggs.
The iridescent bristles of Aphrodita aculeata contain a regular hexagonal array of hollow cylinders. Colour arises from how that structure reflects light, not from pigment, and the effect changes with viewing angle.
Argentine ranching programmes collect caiman eggs from wild nests, rear the hatchlings, and return a proportion to the wild while selling the rest. Because wild nest survival is very low, the scheme can return more animals than would have survived unaided.
Chrysiridia rhipheus flies by day in brilliant colour and was originally placed among the butterflies and even the swallowtails. Its iridescence, like a morpho's, is structural, and its larvae take their poison from a single plant genus.
A Bonellia viridis larva that settles on bare seabed develops into a large female. One that settles on an existing female's proboscis becomes a microscopic male, a few millimetres long, and takes up residence inside her.
A paca's zygomatic arches are enlarged and hollowed into chambers unlike anything in another mammal. Air pushed into them appears to amplify a low rumbling call, which makes the paca's skull a rare example of built-in acoustic hardware.
The Andean cock-of-the-rock carries a permanent semicircular crest of feathers that projects forward over the top of the bill, obscuring it. It is not raised or lowered for display, unlike most crests.
A dugong ploughs a furrow through the seabed, taking whole plants including rhizomes and leaving visible feeding trails. Repeated grazing shifts meadows toward faster-growing, more nutritious pioneer seagrass species, a pattern sometimes called cultivation grazing.
Threaten a swallowtail caterpillar and a bright forked organ everts behind its head, releasing a sharp smell. The osmeterium is a defensive gland, and its chemistry differs depending on which plant family the larva eats.
The macaques that sit in steaming pools at Jigokudani are not following an ancient instinct. The habit began with a single young female in the early 1960s and spread through the troop by observation, one of the best documented cases of cultural transmission in a wild primate.
For centuries European writers used the black swan as shorthand for something that could not exist. Dutch navigators found flocks of them in Western Australia in 1697, and the phrase survived, inverted, as a name for the unforeseen event.
In the cold parts of its range the raccoon dog lays down fat through autumn and then enters a winter dormancy, with reduced metabolism and long periods in a den. No other member of the dog family does this.
The grey heron is the subject of one of the longest-running bird censuses in the world. British heronries have been surveyed almost every year since 1928, producing a nearly century-long record that shows severe winters knocking populations down and mild years letting them recover.
Mandarin ducks nest in holes in trees, often well above the ground. Within about a day of hatching, the ducklings jump out at the mother's call, bouncing on leaf litter and surviving falls that would be expected to injure them.
The name poison dart frog is applied to well over a hundred species, but the practice of wiping dart tips on a live frog is documented for only the genus Phyllobates, and chiefly for the golden poison frog of Chocó.
White-faced capuchins seek out particular millipedes, bite them until they secrete defensive chemicals, then rub the animal vigorously through their fur, often several monkeys sharing one millipede. The secretions include benzoquinones, which repel mosquitoes and other biting insects.
The red bloodworms sold as fish food are chironomid larvae, and the colour is real haemoglobin dissolved in their body fluid. It lets them keep taking up oxygen in lake sediment where almost nothing else with a similar demand can survive.
Stingrays are defined in most people's minds by lying buried in sand. The pelagic stingray abandoned that entirely, living in the open water column far offshore, and its body has been reshaped accordingly.
Tracking shows snowy owls do not follow fixed migration routes. Individuals shift hundreds or thousands of kilometres between years, breeding wherever lemmings are abundant, and some winter far out on Arctic sea ice rather than moving south.
A grouper will swim to a resting moray, shake its head rapidly, and lead it to prey hiding in coral. The eel flushes fish from crevices the grouper cannot enter, and each takes what it catches.
The flesh of an alligator gar is edible, but its roe is not. Gar eggs contain an ichthyotoxin that causes serious gastrointestinal illness in mammals and birds, an unusual chemical defence for a fish that is otherwise armoured purely by scale.
Burrowing owls collect mammal dung and spread it around the burrow entrance. A field experiment found that owls with dung present ate roughly ten times more dung beetles, which points to deliberate baiting rather than lining or odour masking.
A California sea lion named Ronan was trained to bob her head in time to music and could hold the beat across tempos she had never heard, undermining the idea that rhythmic entrainment requires the vocal-learning brain of a parrot or a human.
In the Serengeti, the great majority of wildebeest births fall inside a window of roughly two to three weeks. The synchrony floods predators with more calves than they can take, and a newborn is standing within minutes.