Audition and the processing of acoustic information through hearing is critically important for animals to express territory, find suitable mates, alert others of predators, and much more. Auditory communication is found in many animals via vocalization. Some well-known examples of animals which use auditory communication are: songbirds, bats, whales, crickets, and frogs; however, auditory communication can occur in species which you may have never thought of- like fish! Recently, off the coast of Port Hedland in Western Australia, scientists have found evidence that fish actually sing together in a chorus at dawn and dusk (Parsons et al., 2016). These fish choruses occurred predominantly between late spring and early autumn.
Communication is a two-way street – both producing and hearing sound being important. So what happens when humans introduce noise into an animals’ environment? What would you do if you are trying to communicate with another person in a noisy bar? Perhaps you would talk louder, shift your voice higher, repeat yourself more often and use less complex sentences, or maybe just leave the area. Other animals may exhibit similar behaviors- birds in a noisy environment will also vocalize louder (Brumm, 2004), shift their vocalizations to higher frequencies (Slabbekoorn & Ripmeester, 2008), increase vocal redundancy (Brumm & Slater, 2006), or just avoid the area during times of high noise (Bergen and Abs, 1997).
Noisy environments are associated with increased urbanization. Noise can be introduced through things like: aircrafts flying overhead, automobiles driving down a busy street, the construction or renovation of buildings, neighbors mowing their lawn, ect. Urbanization is increasing globally at a rapid rate, with few places escaping human-induced changes. As a result, urbanization has become a major driver in ecology. One thing we can all agree on is that sometimes being in a noisy environment can be stressful, especially if you are trying to be productive. But how does stress, induced via noise, affect wild animals?
Chronic stress has been linked to important processes, such as the reduction in reproductive behavior. Scientists from the University of California, Riverside, wanted to investigate the effects of anthropogenic noise on endocrine and reproductive function in the White’s tree frog (Litoria caerulea). Kristine Kaiser et al. (2015) used recordings of frogs’ croaking as well as traffic noise to expose two groups of male frogs to different conditions nightly for one week. For one group they exposed frogs to the chorus of croaking only and for the other group they exposed frogs to croaking noises overlaid with traffic noise.
White’s tree frog (Litoria caerulea)
What Kaiser et al. (2015) found was that the group exposed to traffic noise had significantly higher level of corticosterone (a glucocorticoid produced in response to stress) than the group not exposed to traffic noise. Additionally, male frogs exposed to traffic noise had a significantly lower sperm count and sperm viability.
What does all this mean? Urban noise isn’t only affecting us while we are trying to sleep or study, it also affects wild animals and their important biological functions. Kaiser et al. (2016) gave direct empirical evidence that these noises can stress frogs out, as well as lower their reproductive ability. This contribution towards disentangling the complex effects of chronic anthropogenic stress can help us understand and predict how animals are responding to a changing world.
References
Bergen F, Abs M, 1997. Etho-ecological study of the singing activity of the Blue Tit (Parus caeruleus), Great Tit (Parus major) and Chaffinch (Fringilla coelebs). J Ornithol 138:451-467.
Brumm H, 2004. The impact of environmental noise on song amplitude in a territorial bird. J Anim Ecol 73:434-440.
Brumm H, Slater PJB, 2006. Ambient noise, motor fatigue, and serial redundancy in chaffinch song. Behav Ecol Sociobiol 60:475-481.
Kaiser K, Devito J, Jones CG, Marentes A, Perez R, Umeh L, Weickum RM, McGovern KE, Wilson EH, Saltzman W, 2015. Effects of anthropogenic noise on endocrine and reproductive function in White’s treefrog, Litoria caerulea. Conserv Physiol 3(1)
Parsons, M.J., Salgado Kent, C.P., Recalde-Salas, A. and McCauley, R.D., 2016. Fish choruses off Port Hedland, Western Australia. Bioacoustics, pp.1-18.
Slabbekoorn H, Ripmeester EAP, 2008. Birdsong and anthropogenic noise: implications and applications for conservation. Mol Ecol 17:72-83.
Video and Photo credits
Video: Fish chorus – video upload via user “Amazing Zoology”
Photo: White’s tree frog – www.backwaterreptiles.com