When can efforts to control nuisance and invasive species backfire?

Area of Science:

• Population Ecology
• Invasive Species Management
• Conservation Biology

Background:

• Population control via harvesting is a common strategy for managing nuisance and invasive species.
• However, demographic factors and density-dependent processes can lead to unintended outcomes like overcompensation and population instability.
• Previous studies indicate that increased mortality can trigger these undesirable responses in various taxa.

Purpose of the Study:

• To develop a general population model to identify conditions under which control harvest leads to unintended consequences.
• To analyze the potential for overcompensation and population instability resulting from harvest strategies.
• To propose guidelines for assessing harvest risks based on species' life history traits.

Main Methods:

• Development of a general population model incorporating juvenile and adult stages.
• Analytical and simulation analyses to examine harvest impacts.
• Integration of model results with existing literature on nuisance and invasive species.

Main Results:

• High fecundity significantly increases the potential for overcompensation, even with low survivorship.
• Population instability is less frequent, primarily occurring with adult-targeted harvest when fecundity and adult survivorship are high.
• Species with high per capita fecundity, short juvenile stages, and constant survivorship are most susceptible to undesirable responses.

Conclusions:

• Control harvest strategies must consider species-specific life history traits to avoid unintended population dynamics.
• Further empirical studies are needed to validate model predictions on population-level responses to removal efforts.
• The study highlights often-overlooked factors in population control that are potentially applicable across diverse taxa.