Due to human activity, many species have strongly declined in number and are currently threatened with extinction. Management directed at conservation of these species can benefit from the use of simple population models such as matrix models. However, for many species, data on survival and reproduction are scarce. Therefore, we set up a general framework based on a matrix model with three parameters: reproduction, juvenile (=first year survival) and adult survival in which incomplete data can be analysed. This framework is applicable to species that can mature after their first year of life. The point in a calendar year at which the population size is determined, i.e. the census time, is varied. We discuss the differences and the similarities between matrices modelling the same population at different census times. The population growth rate and the elasticity of the survival and reproduction parameters have been determined analytically. From these we made, as a visual diagnostic tool (general framework), plots of the growth rate and the elasticity pattern and their dependence on actual values of the reproduction parameter and the juvenile and adult survival. To illustrate the use of this framework we plot and discuss literature data on survival and/or reproduction of a few bird species with a juvenile stage of one year in the light of our modelling results.
- growth rate
- great tit