|SREL Reprint #2137|
Reproduction under Predatory Threat: Trade-Offs between Nest Guarding and Predator Avoidance in Male Dollar Sunfish (Lepomis marginatus)
DANA L. WINKELMAN
Male dollar sunfish exhibit parental care by building a nest and defending eggs and
larvae against predators. I conducted field observations and experiments to
determine whether intensity of nest defense was related to the presence of
offspring and altered when males faced predatory threats to themselves. I
measured intensity of nest defense as either time spent away from the nest when
threatened with a predator or time spent guarding the nest both in the presence
and absence of a predatory threat. Nest defense increased when eggs and larvae
were present. When males were threatened with a model kingfisher (Ceryle
alcyon) or a model heron (Ardea herodias), males returned more quickly to nests
containing offspring than to nests that were empty. Predatory threat reduced the
time spent guarding the nest and depressed activity level while on the nest.
Habituation to models was not observed. Increased nest defense after spawning
with and without the threat of predation indicates sensitivity to the value of
offspring. However, reductions in nest defense in the presence of a predatory
threat indicate that offspring survival is traded off against parental survival. Nest
guarding in this species is an adaptive response that increases the chance of
offspring survival while ensuring the survival and future success of the parents.
SREL Reprint #2137
Winkelman, D.L. 1996. Reproduction under predatory threat: tradeoffs between nest guarding and predator avoidance in male dollar sunfish (Lepomis marginatus). Copeia 4:845-851.