"Emeritus professor and the study's lead author David Norton said deer populations have grown back to levels seen in the 1950s and 60s.
He told RNZ the decline might not be visible straightaway.
He said deer were hollowing out forests of food sources which support forest ecosystems."
rnz.co.nz
Rising deer numbers drive decline in native forests - research
Ecologists are calling for a deer management strategy, as a new report finds the pests threaten native forests' regrowth.
