The authors study the Hopf bifurcation for the Holling-Tanner predator-prey model. Using Andronov-Hopf bifurcation theorem, they show that for some parameters the bifurcation is subcritical, i.e., there exists a small-amplitude repelling periodic orbit enclosing a stable equilibrium and separating it from another, stable limit cycle. The paper also summarizes earlier results of S.-B. Hsu
and T.-W. Hwang
[SIAM J. Appl. Math. 55, 763-783 (1995; Zbl 0832.34035
)] on global asymptotical stability of the internal equilibrium.