Five variables (nest failure, nest success rate, average
brood size, productivity and chick mortality)
were used to measure the reproductive performance
of Little Grebes in 2003 and 2004 (Table 2)
in a subset of occupied ponds. There were differences
between 2003 and 2004 in the percentage of
successful pairs and productivity whereas the rest
of the variables did not change significantly
between years. Therefore, we used GLMMs for
these two variables and GLMs for the variables
that did not differ among census years. As a measure
of reproductive performance, none of the variables
was related to the pond type or to the pond
occupation frequency using GLMs and GLMMs
(all P-values > 0.1).