Sure, Mark Mar­tell had heard of birds crash­ing into man-made struc­tures, such as sky­scrap­ers, wire­less com­mu­ni­ca­tion towers and wind tur­bines — of­ten fa­tal­ly.

But bridg­es?

“It might just be some­thing about the height of the bridge, but I don’t know,” said Mar­tell, di­rec­tor of bird con­ser­va­tion for Audubon Minnesota, af­ter hear­ing re­ports that mi­gra­tory birds were fly­ing into the new Hwy. 61 Hastings bridge or be­com­ing en­tan­gled in the cables hold­ing up the $130 mil­lion span that con­nects the his­tor­ic river town to Washington County. But while en­vir­on­ment­al­ists and bird ex­perts have spent years study­ing how build­ings in ur­ban areas came to be such pro­lif­ic bird kill­ers, little such re­search has been done on bridg­es, Mar­tell said.

He hopes a new study, com­mis­sioned by the state Department of Transportation, will change that.

The study will be con­ducted amid con­cerns that birds fly­ing back from their win­ter­ing grounds in Central and South America may be killed or injured by fly­ing into the bridge, which cross­es the avi­an ex­press­way that is the Mis­sis­sip­pi River.

More than 300 spe­cies of birds — “mil­lions, if not bil­lions” — fly along the riv­er to and from their win­ter­ing grounds, said the park serv­ice’s Paul Labovitz, who serves as super­in­tend­ent of the Mis­sis­sip­pi River National River and Rec­re­a­tion Area.

“I watched a flight of peli­cans one sum­mer day fly­ing over that took 15 min­utes to pass over me,” Labovitz said last week. “So the num­bers are stag­ger­ing.”

MnDOT of­fi­cials plan to hire an en­vi­ron­men­tal firm to study what makes bridg­es a threat to birds, which they hope will serve as a tem­plate for get­ting ar­chi­tects to buy into bird-friend­ly de­signs in the fu­ture.

“At least in the case of build­ings, we know that there are some things that can be done to re­duce it,” Martell said.

Mar­tell point­ed out that the National Park Service had signed off on the 545-foot tied-arch bridge — of­fi­cials re­ject­ed a cable-stayed de­sign in part be­cause it might pose a threat to mi­grat­ing birds, he said — on the con­di­tion that MnDOT under­take an­oth­er study to bet­ter under­stand the prob­lem of bird strikes on bridg­es.

The study could cost up to $100,000, Mar­tell said.

“The bot­tom line is we just don’t know very much about it, so this parks serv­ice study is some­thing that in­ter­ests us and many oth­ers,” Mar­tell said.

A MnDOT spokes­wom­an did not re­turn calls for com­ment.

“It’s a con­ver­sa­tion that’s been going for ac­tu­al­ly a cou­ple of years, but we’re get­ting to the point where we’re ac­tu­al­ly try­ing to frame what the study’s going to be,” Labovitz said.

“We didn’t have the in­for­ma­tion to in­form this par­tic­u­lar bridge de­sign,” Labovitz said,” but we were hop­ing that this in­for­ma­tion would in­form fu­ture pro­jects.”

Audubon Minnesota has part­nered with the Building Own­ers and Man­ag­ers Association (BOMA), a trade group whose mem­bers rep­re­sent many high-rise build­ings in the met­ro area, on a program called “Lights Out” that en­cour­ag­es build­ing own­ers to re­duce light­ing dur­ing spring and fall mi­gra­tions “in an ef­fort to re­duce build­ing strikes.” So far, of­fi­cials said, the program has en­listed near­ly 60 tall build­ings, in­clud­ing the Wells Fargo Center and the IDS Center.

Some­thing sim­i­lar should be tried on the Hastings bridge, Mar­tell sug­gest­ed, whose lights could be dim­med to avoid con­fus­ing night-mi­grat­ing birds, who navi­gate using the moon and stars and are of­ten at­tract­ed by the glow of light­ing from build­ings.

The U.S. Fish & Wild­life Service es­ti­mates that at least 97 mil­lion and as many as 976 mil­lion birds are killed an­nu­al­ly in the Unit­ed States when they crash into build­ings. There are no fig­ures yet on the num­ber of birds killed when they fly into oth­er man-made struc­tures.

He con­tinued: “You have to won­der in 2014 why we don’t know more about this top­ic.”