The Dunedin Wildlife Hospital is treating eight of the birds which have crashed into glass.
Project Kereru is caring for seven, many of which sustained injuries in the same way.
Project Kereru rehabilitator Nik Hurring said there was usually a rise in window strikes before Christmas, and again at this time of year but the current number being rehabilitated was especially large.
The birds commonly crashed into double-glazed windows as they were especially reflective.
Glare from low winter sun could also contribute.
Kereru could sometimes smash right through older windows, she said.
"I looked after a kereru named Archer last year. He went right through the window of the archery club in Northeast Valley.
"They thought they'd had a break in, but then they saw a kereru inside."
Archer eventually healed up and was re-released.
"In some respects it's better if they go right through, in terms of the physics."
Residents especially concerned about the animals could reduce the likelihood of window strike with decals which were transparent to humans, but reflected UV light to the birds.
However there were likely simpler ways too.
"The best way to start is by standing back from the windows and looking at them and how they reflect things."
Since opening in 2018 the wildlife hospital has cared for more than 105 kereru, most of which sustained injuries due to window strike.
Hospital founder Lisa Argilla said after hitting the glass, kereru often appeared uninjured, but stunned.
"However we know from experience that 95% of them have sustained some sort of fracture because they are heavy birds hitting windows at quite some speed."
Usually they required cage-rest for three to five weeks and a wing-to-body bandage to strap the wing and allow the fractures and dislocations to heal.
Anyone who finds a kereru which has injured itself in that way should call the Department of Conservation.
