Kiran Chug writes about a new technique which is able to accurately estimate bird population size using microphone arrays.
The technique is a world first, and was developed by researchers from the University of Otago and the US Geological Survey. It will be used measure numbers of New Zealand’s only surviving native owl, the morepork, and it’s also hoped it could be used to measure the population sizes of animals such as whales and dolphins.
An excerpt: (read in full here)
“The ovenbird researchers set up four omni-directional microphones which record sound coming from all directions within a 21 square metre area. Over five days, they moved the microphones to 75 localities, where they took five-minute recordings. By combining the recordings from all four microphones, the ecologists came up with a single recording that was fed into a computer program. That program generates a spectogram, which is a graph of the sounds. Each bird has a slightly different sound, which is shown in the graph. Researchers can interpret the graph to count how many birds there are in an area.”