Notes on reproduction Sample Clauses

Notes on reproduction. Although stages A and B are important milestones in the GCC life cycle, field data for these stages are very sparse and difficult to collect. Conversely, fledging rates (i.e. the number of chicks per breeding pair that survive to 5 months) can be determined relatively easily and is a more robust measure. Breeding success is the outcome of the interaction between the proportion of females that breed and the mean number of chicks that each breeding female produces. Two ways to measure this are outlined in Table 1. Table 1: Two alternative methods to calculate breeding success, defined as the mean number of fledglings produced per adult female Measure of productivity Alternative 1 Alternative 2 Proportion of adult females breeding The proportion of all females in the population that breed, where breeding is defined as the act of pairing up. This is measured at time of nesting. The proportion of all females in the population that successfully produced fledglings. This is measured at the time of fledging. Number of fledglings produced The average number of fledglings produced per breeding female (where breeding is defined as per definition in Alternative 1). The average number of fledglings produced per breeding female (where breeding is defined as per the definition in Alternative 2). Table 2 provides an example of how the two alternate methods for calculating breeding success can arrive at the same results. For the purposes of modelling it is critical to ensure that appropriate measures are used. Table 2: Example to illustrate two alternative methods for calculating breeding success Alternative Proportion of females breeding Number of fledglings produced Breeding productivity (fledglings per adult female) 1 0.8 0.80 0.64 2 0.4 1.6 0.64