
TY  - JOUR
A1  - Woodall, PF 
T1  - Kleptoparasitism in Hardheads and Pacific Black Ducks, including size-related differences
JF  - Emu
JO  - EMU
Y1  - 1984
VL  - 84
IS  - 2
SP  - 65
EP  - 70
KW  - 
UR  - https://doi.org/10.1071/MU9840065 
N2  - Hardheads Aythya australis, diving for freshwater mussels in a lake on the Queensland University campus, were chased by other Hardheads and by Pacific Black Ducks Anus superciliosa. Only Pacific Black Ducks and male Hardheads were successful pirates (9.8% of chases), fewer female Hardheads were pirates and they were never successful. More female Hardhead hosts than males dived during a chase and females lost fewer mussels to Pacific Black Ducks than did males. There was no simple relationship between the numbers of pirates and the probability of successful piracy in a chase. During the period of observation, there was a decline in the median time of chases, particularly of female Hardheads, and also a decline in successful piracy (20 to 5%). It is suggested that male and female (= smaller) Hard- heads may form an Evolutionarily Stable Strategy of divers and pirates. 
ER  -

