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 Drafts and withdrawn editions are never mixed into this index.
Male greater prairie-chickens gather each spring on traditional booming grounds, sometimes the same patch of short prairie for decades. They inflate orange air sacs to produce a low three-note call that carries well over a kilometre across open grass.
The elf owl weighs about 40 grams, less than a golf ball, and raises its young in old woodpecker holes drilled into saguaro cactus. The cactus seals the cavity with hard scar tissue, producing a cool, defended chamber known as a saguaro boot.
This dolphin habitually turns onto one flank and trails a flipper through the mud as it moves, nodding its head from side to side. Its eyes have no lens and cannot form an image, so the whole business of finding food is acoustic.
A harbour seal's vibrissae are not simple bristles. They have a wavy, flattened profile that suppresses self-generated turbulence, and blindfolded seals have used them to follow the hydrodynamic trail a fish leaves behind seconds after it has passed.
Once found across Cuba and on the Cayman Islands and Bahamas, this crocodile is now restricted to the Zapata Swamp and a small population in the Lanier Swamp. Interbreeding with American crocodiles now threatens what remains.
Shave a tiger and the pattern is still there. The stripes are laid down in the skin's pigment cells as well as in the fur, so each animal carries a permanent, individually distinctive marking that researchers use to identify it.
A specimen of the cusk-eel Abyssobrotula galatheae was collected at 8,370 metres in the Puerto Rico Trench in 1970, the deepest depth from which any fish has been physically recovered.
When seized, it inflates and secretes a thick white skin mucus that is sticky and irritating. The gum can bind a snake's jaws temporarily and causes enough discomfort that the frog is usually dropped.
Every other insect stops moulting once it has functional wings. Mayflies do not. They emerge from the water as a dull-winged subimago, fly to streamside vegetation, and shed a complete skin, wings included, to become the shining adult.
Adult male southern elephant seals can exceed four metres and weigh several tonnes, far more than any bear or big cat. The sexual size difference is among the most extreme in mammals, with bulls several times the mass of the females they guard.
Adult coho returning to urban streams in the Pacific Northwest had been dying before spawning for decades with no known cause. In 2020 the culprit was identified as 6PPD-quinone, a transformation product of a preservative used in vehicle tyres.
Most geckos have fused transparent eye caps and adhesive toe pads. The leopard gecko has neither: it belongs to a lineage with movable eyelids and plain clawed toes, so it blinks like a skink and stays firmly on the ground.
An adult giant anteater carries not a single tooth. Insects are swallowed whole and broken down in a muscular stomach that mills them with hard folds and swallowed grit, doing the work jaws would normally do.
Howler monkeys produce one of the loudest calls of any land mammal using an enlarged, cup-shaped hyoid bone in the throat. The bone acts as a resonating chamber, and in males it is so large that it displaces the space available for the vocal tract itself.
Canada lynx populations swing on a cycle of roughly ten years, lagging a year or two behind snowshoe hare abundance. The pattern was documented from more than a century of fur-trading records long before anyone measured it in the field.
A swordfish hunting several hundred metres down passes through water near five degrees Celsius. A modified eye muscle warms its eyes and brain by well over ten degrees, keeping vision fast in the cold.
A peacock mantis shrimp accelerates its club so fast that the water behind it cannot keep up. The resulting cavitation bubble collapses with a flash of light and a second shock wave, so the prey is hit twice from one strike.
Makos are the quickest sharks anyone has reliably clocked, with sustained speeds around 30 kilometres per hour and short bursts considerably higher. Many widely quoted top speeds are extrapolations from hooked fish rather than measurements of free swimming.
Sepioteuthis lessoniana was long treated as a single wide-ranging species spread across the Indo-Pacific. Genetic work in Japanese and other regional waters found deeply divergent lineages living side by side in the same waters without interbreeding.
Most familiar gulls have moved inland and onto landfill. The kittiwake did not: it feeds on small fish and plankton at sea, nests on sheer cliffs, and is now assessed as Vulnerable while its scavenging relatives increase.
A gannet hits the sea from up to about thirty metres at high speed. It survives the impact through a set of anatomical features: no external nostrils, a reinforced skull and neck, and a network of air sacs under the skin of the breast and face.
On the River Tarn in southwestern France, introduced wels catfish lunge from the water onto gravel bars to seize pigeons drinking at the edge, then wriggle back. Researchers filmed the behaviour and found roughly a quarter of attempts succeeded.
Eciton burchellii excavates nothing. At the end of each day the colony hangs a bivouac from a log or branch, made entirely of workers linked leg to leg, with the queen and brood held inside.
A shrike hunts like a small raptor but does not have a raptor's feet. Impaling prey on thorns or barbed wire substitutes for the grip that would otherwise hold a carcass steady while the hooked bill tears it apart.