We investigate a population dynamics model that exhibits a Neimark Sacker
bifurcation with a period that is naturally close to 4. Beyond the bifurcation,
the period becomes soon locked at 4 due to a strong resonance, and a second
attractor of period 2 emerges, which coexists with the first attractor over a
considerable parameter range. A linear stability analysis and a numerical
investigation of the second attractor reveal that the bifurcations producing
the second attractor occur naturally in this type of system.Comment: 8 pages, 3 figure