The science behind animal behaviour

Double-Jointed Leg Probe

Clambering • Probing • Methodical

That makes it a mid-frequency system: rhythmic, patient and defined by access rather than speed.

Colour From a Sponge

Feather barbs containing a spongy keratin structure with air spaces of a consistent size but no regular arrangement • Light scattered by that structure reinforcing one wavelength regardless of the direction it is viewed from • A deep even blue that does not shift or flash with angle, unlike the iridescence of a starling or a sunbird

Because the property is constant, it operates as a mid-frequency system.

Socially Inherited Route

Grazing the flush • Flying as a family • Returning to the same ledge

Because a single continuous grazing operation is maintained across a moving geography, it operates as a mid-frequency system.

Material Tucked Into Feathers

The female cutting strips of leaf and bark with her bill • Tucking those strips among the feathers of her rump and flanks rather than carrying them in the bill • Flying to the nest hole with both bill and feet free and unloading the strips there

Because nest building is seasonal, it operates as a low-frequency system.

Shivering Before It Can Fly

Decoupling the flight muscles from the wings and contracting them against each other • Generating heat until the thorax reaches around thirty degrees regardless of the air temperature • Flying in cold, wet and early-morning conditions that ground other bees entirely

Because warming and foraging repeat constantly, it operates as a mid-frequency system.

A Population on Lunar Time

Waiting in forest burrows through the dry season • Moving to the coast en masse when the wet season rains begin • Releasing larvae into the sea at the turn of the high tide on a specific lunar day

Since the cycle is annual, it operates as a low-frequency system.

Taking Cavities Already Occupied

Locating an occupied nest hole • Evicting the residents and destroying eggs or chicks • Holding the cavity and breeding in it

Since takeovers and foraging recur through the day, it operates as a mid-frequency system.

A Sticky Front Leg

Front legs thickened and held folded, used to seize rather than to walk • A dense pad of fine adhesive hairs on the underside of the tibia gripping the prey's surface directly • The captured insect held by adhesion rather than by force while the beak is inserted

Because captures recur through the day, it operates as a mid-frequency system.

Sallying Out and Coming Back

Watching from a low exposed perch • Launching to take an insect in the air • Returning to the same perch and pumping the tail

Since sallies recur within seconds, it operates as a high-frequency system.

Staying Put and Starting Early

Holding a territory through the winter rather than migrating • Beginning to breed weeks before migrants arrive • Fitting in two or three broods before the season closes

Since hunting drops recur constantly, it operates as a mid-frequency system.

Chewed-Fibre Envelope, One Season

Rasping • Pulping • Expanding

Continuous building and provisioning makes this a mid-frequency system.

Forms Locked in One Block

Wearing a tailed, red-bodied, white-patched pattern • Copying a distasteful Pachliopta swallowtail • Protected only where birds have learned that model

The two strategies also work on different timescales, one needing a season of predator learning and the other acting within a single encounter, which makes this a bimodal system.

Pollen-Fed Adult Longevity

Trap-lining the same flowers • Kneading pollen into a drop • Living for months

Since the circuit repeats at one unhurried daily tempo, it operates as a mid-frequency system.

Colour Aimed at Another Animal

Shifting pigment cells and reflective crystal layers within seconds • Producing high-contrast display colours during rival encounters and courtship • Returning to muted greens when no other chameleon is present

Because encounters recur, it operates as a mid-frequency system.

Diving Into the Seabed Itself

Shoaling in open water over sandbanks by day • Driving headfirst into coarse sand with a pointed snout and elongated body • Spending nights and whole winter months buried in the sediment

Since emergence recurs daily, it operates as a mid-frequency system.

Mirror-Sided Counterillumination

Hanging in the twilight zone • Sides reflecting the water • Belly lights matched to the surface

Since the hovering and watching run without interruption in a place that has no day or season, it operates as a mid-frequency system.

A Head Turning Red

An ordinary brown or olive lizard basking, feeding and moving inconspicuously through vegetation

Because the display runs seasonally against a continuous background, it operates as a bimodal system.

Dark Patches Painted on Glass

Broad opaque dark patches of pigment laid into otherwise transparent wing membrane • Those patches held out and displayed during territorial encounters over water • Rivals assessing the patches directly, so disputes over perching sites are settled by display rather than by collision

Because encounters recur constantly, it operates as a mid-frequency system.

Teeth Built for Cracking Nuts

Rows of broad flat molar-like teeth strikingly similar to human molars • Fruit and hard nuts falling into flooded forest during the annual high water • The fish cracking those seeds, digesting some and voiding others intact far from the parent tree

Because the cycle is annual, it operates as a low-frequency system.

Vent-Mineralised Iron Sclerites

Fed by bacteria • Enormous heart running • Plating itself in iron sulphide

Because the circulation and chemosynthesis run continuously at one unvarying rate, it operates as a mid-frequency system.

Gumfoot Lines Under Tension

Anchored • Waiting • Disproportionate

Minimal expenditure and a durable structure make this a single low-frequency system.

Bleeding a Blistering Compound

Feeding openly on foliage in conspicuous stripes • Releasing haemolymph from leg joints when seized • Delivering cantharidin that blisters the skin of whatever grasped it

Since the cycle runs annually, it operates as a low-frequency system.

Ears on the Front Legs

Rubbing a file on one wing across a scraper on the other • Producing a pure carrying tone in short pulses • Hearing it through tympanal membranes on the foreleg tibia

Since chirps repeat several times a second, it operates as a high-frequency system.

One Dove Per Island Group

A genus of fruit doves distributed across the Pacific with each island group holding its own species • Populations separated by sea crossings too long for a small canopy dove to make routinely • Each isolated group diverging in plumage and voice until it no longer recognises or interbreeds with its neighbours

Because divergence runs across evolutionary time, it operates as a low-frequency system.