|Life Cycle Parameter||Default Value in SIMSPAR|
|Maximum Age||5 years|
|Juvenile Mortality||0.40 per year|
|Adult Mortality||0.40 to 0.42 per year|
|Walking Age||23 days|
|Fledging Age||33 days|
|Inter-brood rest period||3 days|
|Clutch Probability (Size:Probability)||2 eggs:0.16/ 3 eggs:0.48/ 4 eggs:0.36|
|Sex Ratio (Male:Female)||0.5:0.5|
A number of life cycle parameters influence the sparrow's populations dynamics within the model. Each breeding season, the model determines if any individuals are greater than 5 years of age. If they are, these individuals die off since it represents the physiological limit placed upon their longevity. At each time step, the model randomly chooses a number of adults that die based on an annual probability of 0.40. Juvenile mortality, a linear density-dependent model that ranges form an annual probability of 0.40 to 0.42, is determined by the number of successful territories in the juvenile's nesting cell. At the minimum density of one nest per cell the mortality rate is minimal and at the maximum nesting density the juvenile mortality is maximal.
The nesting cycle and its interval lengths are based on field data (see Lockwood, et al., 1997, Wilson Bulletin 109: 720-731). The sex ratio of juvenile birds is assumed to be 50/50 and the clutch size varies according to a set range of probabilities.