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 Drafts and withdrawn editions are never mixed into this index.
At dusk many parrotfish secrete a transparent envelope of mucus from glands near the gills and spend the night inside it. Experimental work indicates it reduces attack by blood-feeding gnathiid isopods.
Hamadryas society nests one grouping inside another: a single male with a few females forms a unit, several units form a clan, clans form a band that forages together, and bands converge at night into cliff-side troops that can number in the hundreds.
Eggs laid on leaves above a pond can sense the vibrations of a snake or wasp attacking the clutch and hatch within seconds, dropping into the water days ahead of schedule.
A numbat consumes something on the order of twenty thousand termites a day, gathered with a long sticky tongue. It is also one of very few strictly diurnal marsupials, because its schedule is set by when termites are near the surface.
A black fly larva anchors itself to a rock in fast water with a ring of hooks and a pad of its own silk, then opens a pair of feathery head fans into the current and combs out whatever the river carries past.
Tracking with flight recorders showed Andean condors flapping for barely one per cent of their time airborne. One bird flew more than five hours and over 170 kilometres without a single wingbeat, riding thermals and slope lift instead.
A frigatebird spends most of its life over open ocean but has almost no waterproofing and very small feet. It cannot take off from the surface, so it must snatch food while flying, or take it from a bird that has already caught some.
Despite the old name white ants, termites sit inside the cockroach order Blattodea. Their nearest living relatives are the wood-eating Cryptocercus cockroaches, and their resemblance to ants is pure convergence.
Analyses of recorded brown thrasher song have catalogued repertoires running into the hundreds and by some counts over a thousand distinct song types, placing it among the largest documented repertoires of any North American bird.
Rather than patching damage, many orb-weavers take the old web down by eating it, recovering the silk proteins, and spin a fresh one. A garden spider can therefore work each day on a snare that no longer exists by evening.
From the 1930s to the 1960s hospitals injected women's urine into a female Xenopus laevis. If the woman was pregnant, hormones in the urine made the frog lay eggs within about a day.
A rolling dung beetle needs a straight line away from the pat, not a destination. Experiments in a planetarium showed African ball-rollers hold that line at night using the bright streak of the Milky Way.
Honduran white bats bite through the side veins of a Heliconia leaf until the blade folds down into a tent. A small group shelters beneath it, and the green light filtering through turns their white fur the colour of the leaf.
Mudpuppies keep external gills for life, and the gills are not a fixed shape. In warm, still, oxygen-poor water they are large and bushy; in cold, fast, well-oxygenated water the same animal carries markedly smaller ones.
The initial contact is often barely noticed. Twenty to forty minutes afterwards comes severe back and muscle pain, vomiting, sweating and a surge in blood pressure, a systemic reaction from a jellyfish whose bell is about a cubic centimetre.
A barnacle larva chooses a rock, cements itself down by the front of its head, and grows a shell around itself. From then on it kicks food into its mouth with its legs, which is why Louis Agassiz described it as an animal standing on its head.
Because a moray cannot create suction in a narrow crevice, it launches pharyngeal jaws forward from the throat, grips the prey with them, and drags it backward down the gullet. The mechanism was filmed in 2007.
A reed warbler builds a deep cylindrical cup lashed to several vertical reed stems rather than resting on anything. The depth matters: it keeps eggs and chicks inside while the reeds sway in wind that would empty a shallow nest.
Many ruby-throated hummingbirds fly non-stop over the Gulf of Mexico on migration, a water crossing of roughly 800 kilometres. They do it by nearly doubling their body mass in fat before departure rather than by any trick of gliding.
Durian flowers open in the late afternoon and shed their petals before dawn, giving pollinators a single night. Nectar-feeding bats do most of the work, and orchards without them set noticeably less fruit.
On cold desert mornings a greater roadrunner turns its back to the sun, raises its feathers and exposes a patch of black skin between the shoulders. Absorbing solar heat directly lets it climb out of an energy-saving overnight torpor without burning food.
Video and tagging show great hammerheads cruising rolled between fifty and seventy-five degrees from upright for up to ninety percent of their time. The posture turns the tall dorsal fin into an extra lifting surface and cuts the energy cost of swimming by roughly a tenth.
On islands off Thailand and Myanmar, long-tailed macaques carry stones down to the tide line and use them to open oysters, snails and crabs. They choose different stone shapes for different prey, and the habit is confined to particular coastal groups.
Male common yellowthroats wear a black facial mask that varies in size between individuals. In one long-studied population, mask size predicted a male's immune gene diversity and his success with females, tying an ornament to disease resistance.