The predatory and foraging behaviour of brown hyenas is observed at mainland Cape fur seal breeding colonies to
- assess the availability,condition and accessibility of seals for brown hyenas,
- evaluate the importance of the coast for brown hyena abundance, movement and energy budget,
- determine factors influencing the foraging related time budget of brown hyenas,
- assess feeding preferences, and
- examine the consumption of prey.
Behavioural observations and seal pup mortality data is recorded at the different seal colonies and GPS collars have been fitted on coastal brown hyenas to determine their movement.
Live seal pups are available for brown hyenas all year round, but their increasing size, mobility and activity, as well as the attendance pattern of adult females may influence the brown hyena’s foraging behaviour. Many dead pups are also available to scavenge during the pupping season (November to January) and represent an easy and safe way to obtain food.
The results of this on-going study showed that brown hyenas preferred to kill seal pups despite the availability of carrion. The predation rate was unrelated to carrion availability, but the absolute number of kills was positively correlated to seal pup density. Increasing seal pup density led to an increase in brown hyena capture rate and hunting efficiency. Furthermore the overabundance of easy and vulnerable prey led to surplus kills.
However, brown hyenas foraged opportunistically by scavenging, killing and caching seal pups in proportion to their occurrence at the colony, and hence, caused an additional impact on seal pup mortality by not only choosing the doomed surplus. Brown hyenas preferred to consume larger and heavier prey, but a large proportion of the brown hyena’s prey was only partially consumed. Selectivity increased with seal pup density, and feeding and handling times per prey item were reduced.
Although black-backed jackals outnumber brown hyenas and are their main competitors at seal colonies, they did not influence the brown hyena’s foraging strategy.
Future observations of foraging brown hyenas outside the pupping season and at night could yield additional interesting information about adaptations in predatory and foraging behaviour to changes in seal behaviour, abundance and attendance.