Durban — Two Fridays ago, Durban snake rescuer Nick Evans and veterinarian Dr Carla Goede rescued two black mambas in Chatsworth and Yellowwood Park respectively.One of the rescues was a close call.Evans said Durban has a healthy black mamba population because of suitable habitat and an abundance of the house rat, an invasive species (there are a few other factors).He said Durban was not the cleanest place, unfortunately, so rats are happy here.Last Friday Evans and Goede answered a call in Chatsworth for a black mamba in a chicken coop.Chicken coops or farms and breeders of other bird…