This is a discrete time model of birds designed for simulation of West Nile virus in bird populations, when coupled to a mosquito model.
Birds progress through an egg, fledgling, juvenile, and adult stage. Sexual maturity is reached at the adult stage. Egg and fledgling stages are not capable of flight. Juveniles are capable of flight, but do not mate, and consequently disperse to find a nest. Birds capable of flight distribute their risk according to a time spent matrix giving their home range.
A function for mating gives the time-varying (usually a yearly pulse) at which birds seek out a mate, find a nest, and lay eggs. The model assumes these 3 events occur simultaneously, and that nest finding uses a different dispersal matrix which will cause actual dispersal of birds.
Nestling and adult life stages can transmit disease between each other (see Overwintering of West Nile virus in a bird community with a communal crow roost). There is no vertical transmission. Density-dependent mortality occurs in the fledgling and juvenile stage.