Strik­ing out

Col­li­sions with win­dows are a grow­ing threat to bird pop­u­la­tions. Can tech­nol­ogy come to the res­cue?

Australian Geographic - - Contents - By Rachel Fether­ston

MOST OF US HAVE ex­pe­ri­enced it at some time – the distressing thud that sig­nals a prob­a­bly fa­tal col­li­sion of bird and win­dow. Such oc­cur­rences are a grow­ing con­ser­va­tion con­cern; win­dow col­li­sions kill more birds than any other hu­man-re­lated fac­tor ex­cept habi­tat de­struc­tion. Es­ti­mates sug­gest the num­ber of birds killed like this glob­ally each year could be in the bil­lions.

Aus­tralian or­nitho­log­i­cal con­sul­tant Stephen Ambrose has spent al­most two decades ad­vis­ing coun­cils, ar­chi­tects and de­vel­op­ers on how to im­prove build­ing de­sign to re­duce the risk of bird strikes. Col­li­sions, he ex­plains, are mostly caused by birds try­ing to reach habi­tat they can ei­ther see through the win­dow or re­flected in it.

He adds that mi­gra­tory species are par­tic­u­larly at risk, al­though the pre­cise im­pact bird–win­dow col­li­sions are hav­ing on Aus­tralian species has yet to be stud­ied in de­tail. One ex­cep­tion is the crit­i­cally en­dan­gered swift par­rot, the only bird species known to be ad­versely af­fected by win­dow-strike mor­tal­ity at the pop­u­la­tion level.

As its name sug­gests, the swift par­rot is a fast flyer, typ­i­cally trav­el­ling in flocks as it mi­grates from Tas­ma­nia to the south-east­ern main­land of Aus­tralia. It tends to fly at or below tree-top level, which puts it at par­tic­u­lar risk of win­dow col­li­sions.To make mat­ters worse, its favoured main­land habi­tat is forested ar­eas, and these hap­pen to be where more and more homes are be­ing built, in­creas­ing the chance of col­li­sions.

It has been es­ti­mated that each year up to 2 per cent of the swift par­rot breed­ing pop­u­la­tion – which is down to a mere 2000 or so birds – is killed as a re­sult of col­li­sions with win­dows, fences (es­pe­cially chain-link fences) and ve­hi­cles.

AN­OTHER SPECIES at­tract­ing con­cern is the pow­er­ful owl, which is threat­ened in New South Wales. “Re­cently there has been a sig­nif­i­cant in­crease in the num­ber of

pow­er­ful owl strikes in Syd­ney,” Stephen says. Again, the en­croach­ment of res­i­den­tial de­vel­op­ment into bush­land is ex­ac­er­bat­ing the prob­lem.

Stephen is also con­cerned that “mul­ti­ple high-rise build­ings are be­ing built near in­ter­na­tion­ally im­por­tant wet­lands in ma­jor cities and towns in Aus­tralia”.This trend is likely to lead to an in­crease in in­ci­dents such as the one that saw an im­ma­ture white-bel­lied sea-ea­gle killed in Syd­ney’s CBD af­ter it col­lided with a tall build­ing.

Dis­ap­pear­ing nat­u­ral habi­tat is also driv­ing more birds into ur­ban ar­eas – a process that’s ac­cel­er­ated by our ef­forts to at­tract them. “Aus­tralians love land­scap­ing their gar­dens, feed­ing birds and pro­vid­ing wa­ter baths for them,” Stephen says. “This, in turn, at­tracts birds to peo­ple’s gar­dens, which is fan­tas­tic.” The down­side is that draw­ing birds into an ur­ban en­vi­ron­ment in­creases the like­li­hood they’ll fly into a win­dow at some point.

It’s not only win­dows that are a prob­lem. Bar­ri­ers erected to shield res­i­dents from the noise of busy roads are also a ma­jor is­sue. “There are re­ports of birds, es­pe­cially par­rots, smash­ing into the glass or fi­bre­glass bar­ri­ers in an at­tempt to reach the trees on the op­po­site side of the road,” Stephen ex­plains.

“As a re­sult, road ar­chi­tects and engineers now con­struct road bar­ri­ers that are vis­i­ble to wildlife.”

Stephen be­lieves that at­tempts to re­duce bird–win­dow col­li­sions are slowly gain­ing mo­men­tum in Aus­tralia. “Most ar­chi­tects and engineers are quite re­cep­tive to mod­i­fy­ing their de­signs or us­ing dif­fer­ent build­ing ma­te­ri­als to re­duce the risk, if it’s ex­plained log­i­cally and sen­si­bly,” he says. “It usu­ally just in­volves tweak­ing things here and there, rather than ma­jor re­designs, which makes it eas­ier to gain the sup­port of the builders.”

There is still much room for im­prove­ment, how­ever, par­tic­u­larly in re­gard to the de­sign of ma­jor build­ings in Aus­tralia’s cities.

“Many new high-rise and other large city build­ings have lots of glass win­dows, and plaza ar­eas are of­ten land­scaped with canopy trees and shrub­bery,” Stephen says. “While many of these de­signs are aes­thet­i­cally pleas­ing, they do in­crease the risk of birds strik­ing glass panes.”

Bar­ri­ers shield­ing res­i­dents from the noise of busy roads are also a ma­jor is­sue.

Birds fly­ing into win­dows usu­ally strike head-first, re­sult­ing in con­cus­sion or a bro­ken neck.

Newspapers in English

Newspapers from Australia

© PressReader. All rights reserved.