NOTES ON MALE SPERM WHALE REACTIONS TO KILLER WHALE ATTACK IN A HIGH LATITUDE FEEDING GROUND

NOTES ON MALE SPERM WHALE REACTIONS TO KILLER WHALE ATTACK

IN A HIGH LATITUDE FEEDING GROUND

Marta Acosta, Heike Vester, Ricardo Antunes, Iva Kovacic & Luca Tassara

INTRODUCTION- Killer whales have a broad diet

- Aggressive interactions may underline ecological interactions (e.g. prey competition)

- To date, agressive interactions between killer and sperm whales, refer to female groups with calves

- First compilation of (3 events) harassment/attack of killer whales towards adult male sperm whales and their response

EVENT 1

Late 90´s:

A small group of killer whales was observed approaching and harassing a male sperm whale, that responded by defecating until the attackers left

EVENT 230/07/2009:

A male sperm whale that surfaced in the middle of a group of killer whales feeding on herring triggered an aggressive response. The whale repelled the attack by shaking its peduncle 90º sideways

EVENT 323/07/2011:

- 4 sperm whales vs 5 killer whales (1 calf)- Sperm whale diving interruption and

clustering- Acoustic response: 5R, 5+1- Silent killer whales?- Slight wounds

CONCLUSIONS- First compilation of killer whale

harassment/attack on male sperm whales- Not homogeneous sperm whale response- First evidence of social response among males- Killer whale behaviour consistent with previous

reports- Predator-prey? Competition?

THANKS!!

macostaplata@gmail.com