Global Soundscape Patterns

As someone who studies ecosystem and animal sounds, it is hard not to get a little anxious in the middle of winter in Syracuse, New York, when all one hears is wind, human noise, and the occasional crow or house sparrow. The winter soundscape at high(ish) latitudes is a far cry from the blissful bird-, frog-, and insect-dominated soundscapes that we hear during spring and summer mornings and evenings, especially if we live outside of the city.

I have developed an interest in these annual soundscape patterns, and the differences in these patterns between tropical and temperate regions. A microphone placed in a temperate forest for one year would pick up a drastically changing signal from season to season, with the spring and summer dominated by animal choruses, the fall by the rustling of leaves, and the winter by the howling of winds. In the cold months, birds migrate to warmer climates, frogs hibernate, and insects become dormant or overwinter as eggs, leaving us with a bleak acoustic environment compared with that of springtime. However, in the less seasonal tropics, animal sounds can be a major aspect of the soundscape in every month of the year. Many places in the tropics likely do not experience such high variation in soundscape characteristics throughout the course of the year. A walk through the tropical rainforest at dawn, on any day of the year, will likely be accompanied by a cacophony of biological sound.

Morning rainforest soundscape in Borneo. Recorded in Kubah National Park by C. Swider

Acoustic complexity during any particular season is another soundscape characteristic that may vary with latitude. One might anticipate a more complex soundscape in a tropical rainforest than in a temperate forest, given the difference in the biodiversity between habitats. But is this necessarily the case? Perhaps not…

Investigating the differences in soundscape complexity and seasonal trends between temperate and tropical regions is one of my goals for the coming months. I hope to present some of my work at the joint conference of the Acoustical Society of America and the European Acoustics Association in June, at which there is a special session devoted to ecosystem acoustics. Thanks for reading!

Colin Swider, PhD student