A type IV functional response with different shapes in a predator–prey model

•We consider a predator–prey model.•We develop a functional response representing group defense using timescale separation.•The resulting functional response does not necessarily have to be dome-shaped but can also be monotonically increasing.•The system is analyzed using bifurcation analysis.•A paradox is identified. In certain parameter regimes, higher group defense of the prey can rescue its predator from extinction.