Scientists say the world's songbird p­opulations are declining and a new documentary looks at how humans are contributing to the problem.

The Calgary Wildlife Rehabilitation Society is hosting ‘The Messenger’ on Friday and Saturday night to raise awareness about the depletion of the songbird population on multiple continents.

The film’s director, Su Rynard, travelled the globe to document the decline and says one of the biggest challenges was capturing the birds in flight, especially in the dark.

“One of the things that's really interesting about songbirds is they do these huge, epic migrations every year and these are tiny birds and they actually fly at night. Then the question was, well how on earth would you film this tiny, little bird way up in the sky,” said Rynard.

Rynard teamed up with Western University's Avian Research Department and used a wind tunnel and high speed camera to photograph the birds in flight.

“One of the issues of flying birds in the wind tunnel is making them think they’re actually flying in nature.  In our experiments we simulate a night environment with very low light levels, but of course that's not compatible with trying to shoot high speed imagery of birds in such beautiful colour so we had to completely redo the lighting in the tunnel,” said Chris Guglielmo, Avian Wind Tunnel Researcher.

Jenna McFarland and Andrea Hunt are with the Calgary Wilderness Rehabilitation Society and say they have seen first-hand how window strikes can injure songbirds.

“Hit a window, they get some immediate swelling on their brain, which applies pressure and limits the mobility to their limbs, so we see that their eyes close, their wings stop moving, their legs stop moving. We don't like to see any fractures, fractures are always bad news with little, tiny bones that we can't put back together,” said McFarland.

It's the first time the society has hosted a movie night and a question and answer session will follow the screening.

“We're able to bring in our own experts, some of our staff who are very knowledgeable and have been working in wildlife rehabilitation for years who are going to be able to answer some of the questions that the public might have after watching this film,” said Hunt.

The Messenger will be shown at the Globe Cinema at 617 8th Avenue S.W. on March 4th and 5th at 7:00 and 9:10 p.m.

The Calgary Wilderness Rehabilitation Society has a number of tips on how you can reduce bird strikes in your yard, click HERE for more information.

(With files from Kevin Fleming)