Reaction of reed warblers to cuckoo eggs

Explain that in all graphical displays (bar charts, stacked bar charts and pie charts), the area of ink used for each category is in proportion to its frequency (or relative frequency);

Cuckoos are birds that lay their eggs in the nests of other species then leave them to be raised by the nest's owner. A high proportion of Great Reed Warbler (Acrocephalus arundinaceus) nests are parasitised in this way by the European Cuckoo (Cuculus carnorus) in central Hungary. Ecologists studied several nests and the bar chart below shows the reaction of the 71 Great Reed Warblers that had a single Cuckoo eggs laid in their nests. (Egg burial can occur if the cuckoo egg is laid before any of the host eggs and the nest is then built up over this egg.)