Whale be­hav­iour

Australian Geographic - - CONTENTS - JOANNA KHAN

WHEN UN­DER WA­TER, hump­back whales mostly seem to move de­lib­er­ately and grace­fully, but above wa­ter they’re known for en­er­getic, some­times air­borne, dis­plays. These ma­rine mam­mals can throw their mas­sive bod­ies around with sur­pris­ing agility, slap­ping, splash­ing and breach­ing. Re­searchers be­lieve these be­hav­iours of­ten have roles in com­mu­ni­ca­tion or mat­ing, but some­times they seem to be just for sheer joy. Hump­backs spend the sum­mer months feed­ing on krill in the South­ern Ocean, be­fore set­ting off on an­nual mi­gra­tions up Aus­tralia’s east and west coasts to breed in trop­i­cal waters. You’re most likely to see their re­mark­able sur­face ac­ro­bat­ics in Aus­tralian waters be­tween May and Novem­ber. 1 Breach­ing The whale beats its tail to launch from the wa­ter and twists its body in the air, be­fore crash­ing down on the back or side, cre­at­ing a huge splash with flail­ing pec­toral fins. In­di­vid­u­als can breach re­peat­edly – this could re­late to com­mu­ni­ca­tion, dis­lodg­ing skin par­a­sites or per­haps just be­cause it’s fun.

2 Flip­per (fin) slap A pec­toral fin is raised out of the wa­ter and slapped down forcibly, mak­ing a sound that can be heard for kilo­me­tres, above and be­low the wa­ter. It may be used by males to at­tract fe­males or to com­mu­ni­cate with other whales in the area. 3 Fluke slap The whale force­fully smacks the tail flukes down onto the wa­ter’s sur­face, mak­ing a loud slap, that may sig­nal its po­si­tion to other whales. This may be per­formed re­peat­edly.

4 Lat­eral fluke The whale dis­play swims on its side with one tail fluke and one pec­toral fin out of the wa­ter, of­ten seen in pods of males com­pet­ing for fe­male at­ten­tion. Some­times when a hump­back is rest­ing, it may swim gen­tly through the wa­ter on its side, slic­ing the sur­face with one tail fluke and one pec­toral fin.

5 Pe­dun­cle slap/ tail throw The whale karate chop – it strikes the base of its tail (pe­dun­cle) side­ways onto the wa­ter, usu­ally an ag­gres­sive be­hav­iour dis­played by com­pet­ing males. Un­like a fluke slap, a pe­dun­cle slap or tail throw is when the whale uses all of the tail (flukes and base/ pe­dun­cle) to strike the wa­ter.

6 Spy hop The whale slowly raises its head ver­ti­cally out of the wa­ter, mouth closed, un­til the eyes are just above the wa­ter­line. This could be to see what’s hap­pen­ing above the sur­face, and may be done by in­di­vid­u­als or groups, prob­a­bly not for com­mu­ni­ca­tion.

It is jok­ingly termed ‘hu­man watch­ing’ when ob­served by peo­ple from boats.

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