Among the given species, the Z value is highest for

Ecologists have discovered that the value of Z lies in the range of 0.1 to 0.2, regardless of the taxonomic group or the region (whether it is the plants in Britain, birds in California or molluscs in New York state. But, for frugivorous (fruit-eating) birds and mammals in the tropical forests (e.g., Amazon forest) of different continents, the slope is found to be 1.15.