Since July 2016, 38 kererū have been treated at Wellington Zoo’s animal hospital after flying in to windows.

It appears kiwi aren't the only treasured New Zealand birds who have trouble flying.

Kererū – the runner up in the 2017 Bird of the Year competition – are having more difficulty negotiating windows than their feathered friends, figures from Wellington Zoo show.

Since July 2016, 38 kererū have been treated at Wellington Zoo's animal hospital after flying into windows – nearly five times the number of all other native bird hospitalisations for window strike combined.

NICHOLAS BOYACK/STUFF The mark left by a kererū after flying into a window in Lower Hutt.

Senior vet Baukje Lenting said window strike was a real problem with 20 to 30 native birds being treated at the zoo's wildlife hospital each year. Many more cases likely went unreported, she said.

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The zoo currently had two or three kererū recovering from window strike in its care.

Statistics from Wellington Zoo show kererū are more likely to fly into windows than other native birds.

The other birds treated since July 2016 were four tūi, two kākā, a kākāriki and a shining cuckoo.

Although she could not definitively say why such high numbers of kererū were being injured, Lenting said fledglings made up a high proportion of window strike victims.

"[Many come in to the zoo's care] at the time [when] the birds are fledging – inexperienced birds heading out into the world who haven't encountered windows before and haven't mastered flying just yet."

WELLINGTON ZOO Wellington Zoo senior veterinarian Baukje Lenting with a kererū recently brought into the zoo after suffering injuries from a collision with a window.

Overseas studies suggested incidents often happened with large windows that were close to food sources or surrounded by vegetation.

Collisions could happen when birds could see a flight path through one window and out another behind it or were confused by vegetation being reflected off the glass.

In Wellington, many window strike incidents happened in urban areas near native bush where birds often only saw windows at the last minute or not at all.

Peter Rees Photography Tūi also occasionally suffer from incidents of window strike.

The birds commonly received chest and shoulder injuries, which could be fatal. Head injuries were less common.

If people wanted to do something about window strike, they could make windows a more obvious barrier, Lenting said.

Some organisations stock decals that reflect ultraviolet light. Invisible to the human eye, it can be seen by birds and helps them identify a window before they hit it.

If the public came across injured native birds, the best thing they could do was to place the bird in a box and take it to Wellington Zoo's animal hospital to be assessed. Non-native birds could be taken to the SPCA, Lenting said.