BBC Wildlife - UK (2020-09)

NorbertClockwise from butterfly: Getty; Paul Souders/Getty; Getty;

Probst/Getty;

Bob

Hunter/Getty;

Br

an

Masters/Getty

A

fairquestion,givenBritain’s

recordsunshinein2020.Infact,

themaindangeris notoverheating,

butdesiccation.Smallcreatureslike

insectshavea proportionallygreater

surfaceareafortheirsize.Sowhile

theyhavetheprotectionofa nearly

waterproofwaxycuticlecoveringtheir

bodies,theycanstilllosemoisture

dangerouslyeasily.Theythenfind

it difficulttoreplenishlostwater,as

nectarsources,dew,dungandmuddy

puddlesdryup.Onthehottestsummer

days,butterfliesactiveinthemorning

oftenseekshelterbynoon,andthe

caterpillarsofspeckledwoodbutterflies

maystopfeedingduringhotperiods,

resuminginautumn.RichardJones

Cansummers

gettoohotfor

butteries?

LEPIDOPTERA

ORNITHOLOGY

T

heEurasiancuckoois farfrom

unique,andofallthecuckoo-type

birdsonthewesternsideof‘thepond’,

thebrown-headedcowbirdis perhaps

bestknown.Thisbroodparasiteis

equallycraftyaboutraisingitsyoung

withoutreallyraisingitsyoung.Butit

hasa peculiarbehaviourofitsown.The

femalecowbirdwillstalkthehostbird,

suchasa warbler,sparroworblackbird,

andtomakesureshelayshereggatthe

righttime,shemaydestroyitsclutchor

eventheyoungornestitself.This

forcesthehosttostartover,enabling

thewatchingcowbirdtolayinsync.

AlsounliketheEurasiancuckoo,

cowbirdnestlingsgrowupalongside

hostchicks,butoutcompetethem.

Nestlinggrowthratesofthehostmay

decreaseduetotheparasiticcowbird’s

greaterdemands.If thehostspeciesis

alreadyunderconservationpressure,

thiscanhaveanimpact.

LaurenPharr

Docowbirdsharmotherbirds?

BIOLOGY

W

e oftenseemoremolesduringlong

spellsofhot,dryweather,becausethey’re

forcedintotheopenastheearthhardens.But

aretheirspade-likeforelimbs,whichworksuch

a treatunderground,anygoodaboveit?The

evolutionarytrendamongfour-leggedland

animals,ortetrapods,hasbeentomovefroma

sprawlingposturetoanuprightonethathelps

‘stack’weightverticallythroughtheload-bearing

limbs.Perfectforwalking– butnottunnelling.

Sincemolesdoboth,theyhavecomeupwith

a two-for-onedesign.Theyretaina sprawling

posturefordigging,whileabovegrounda

sixthdigit,orfalsethumb,helpstolifttheload

duringtheupwardphaseoftheircommando-

crawl-likegait.Ungainlyperhaps,yetit works!

GillianBurke

Howdomoleswalk?

Pushyparent:the

brown-headed

cowbirdmaykill

otherbirds’young.

Molesspendalmost

alltheirlivesdigging

underground,butwill

occasionallycometo

thesurface.

Butterflies enjoy

the sun – but not

too much.

Q&A

82 BBC Wildlife September 2020