AboutZoos, Since 2008


High­way traf­fic noise inter­feres with for­ag­ing effi­ciency of bats and owls

pub­lished 24 Sep­tem­ber 2011 | mod­i­fied 21 April 2011

The for­ag­ing per­for­mance of acoustic preda­tors like bats is impaired by the noise which humans pro­duce. This anthro­pogenic noise pol­lu­tion should be included in envi­ron­men­tal impact assess­ments of human activ­i­ties, accord­ing to Ger­man researchers Siemers and Schaub. They con­ducted research on the for­ag­ing suc­c­cess of mouse-​eared bats under dif­fer­ent cir­cum­stances, sim­u­lat­ing the noisy envi­ron­ment of a highway.

The results show that the bats need more search time to locate their prey when get­ting closer to the acousti­cally sim­u­lated high­way. In other words, it gets harder for the bats to find the large ground-​running arthro­pods, that make only faint rustling sounds, by ear. Nev­er­the­less it is amaz­ing that the bats per­form above chance level, when detect­ing and local­is­ing the faint sounds of the arthro­pods under the noisy cir­cum­stances so close to the ‘heavy-​used’ high­way. This is prob­a­bly due to the fact that these acoustic preda­tors evo­lu­tion­ar­ily are adapted to for­ag­ing under con­di­tions with nat­ural noise such as wind or run­ning water.

The study pro­vides exper­i­men­tal evi­dence that traf­fic noise (and prob­a­bly other anthro­pogenic noise) degrades for­ag­ing habi­tat qual­ity for acoustic preda­tors like bats, and prob­a­bly also owls, car­ni­vores and oth­ers. Through inter­fer­ence with the preda­tors sen­sory per­for­mance or atten­tion, the traf­fic noise can reduce pre­da­tion pres­sure. This could alter the predator-​prey dynam­ics, which in turn could ulti­mately inter­fere with ecosys­tem sta­bil­ity. There­fore, the researchers sug­gest that the effect of anthro­pogenic noise and other sen­sory pol­lu­tion should be part of the assess­ment of the envi­ron­men­tal impact of human activities.

Though not sur­pris­ing, it is unnerv­ing to realise how dis­turb­ing human activ­i­ties are for ecosys­tems and as a con­se­quence for the ser­vices they pro­vide, such as clean water, clean air, food and other life­sav­ing basic mate­r­ial. (Source: ‘Hunt­ing at the high­way: traf­fic noise ……’ by Siemers and Schaub, Pro­ceed­ings of the Royal Soci­ety, 17.11.2010)

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