Ovivorous opportunities: Predation events during nest guarding in a colonial-nesting fish species

The construction and defence of nests leading up to and following spawning
is widespread across many freshwater fish species. Despite the known role
of nesting in sexual selection and the establishment of social hierarchy,
how nesting and nest guarding behaviour may shape predation risk for both
offspring and nest guarding individuals remains relatively underexplored.
Here, we documented a novel interaction between a nest guarding fish
species, the pumpkinseed sunfish (Lepomis gibbosus), and common snapping
turtles (Chelydra serpentina) during the pumpkinseed nesting period. Field
surveys were conducted over three days in an Ontario wetland to document
nest densities, predator presence, and predation attempts by potential
nest predators. A total of 118 pumpkinseed nests were observed, with all
but five nests located in colonies. In nine instances, adult snapping
turtles were recorded inspecting guarded pumpkinseed nests. On two
occasions, snapping turtles were observed consuming nest contents, as
indicated by a gulping motion while on the nest. Male pumpkinseed
exhibited defensive behaviours, such as diversion and aggression.
Following these interactions, we returned to quantify nest abandonment in
three nests and observed that pumpkinseed had abandoned each nest within
48 hours. While no observations of predation by snapping turtles on adult
sunfish were made, other opportunistic predators made foraging attempts on
guarding males. Though nest guarding can improve egg and offspring
survival, our results document that predators are still capable of
consuming nest contents even while guarded. Omnivorous foraging on fish
eggs that are only briefly available to consumers but spatially aggregated
in specific spawning habitats and nest colonies warrants future work
evaluating the impact of nesting for: 1) adult and offspring survival
across systems with divergent predator communities, and 2) the
contribution of egg consumption to the seasonal energy budgets of egg
predators.