Great cormorant rookery

Great cormorants (カワウ) are nesting in trees along Yasugawa (野洲川) in Iseochi, Ritto City. When I visited the rookery on April 11, 2020, dense foliage obscured my view of the birds, making photography nearly impossible.

Cormorant nests in bamboo woods along Yasugawa in Iseochi, Ritto City

Audio recording

Their vocalizations were very clear, however, so I made an audio recording. As the location is near the Meishin Expressway and small factories along Japan Route #1, I added a high-pass filter to reduce the low frequency rumble of traffic and machinery. Readers may download this processed version or the unprocessed recording with no filters.

Great cormorant rookery in Iseochi, Ritto City with high-pass filter at 220Hz, -12dB/octave roll-off

Recording was done with a Sony PCM-M10 recorder and FEL Communications Clippy Stereo EM172 Microphones clipped to the sides of a small backpack. This method of quasi-binaural recording separates left and right channels with a barrier between omnidirectional microphones.

Audio recorder and mics on backpack in Iseochi, Ritto City, leaning on a stone marker by the Ministry of Land, Infrastructure, Transport and Tourism (国土交通)
Audio recorder and mics on backpack along Yasugawa in Iseochi, Ritto City, leaning on a stone marker by the Ministry of Land, Infrastructure, Transport and Tourism (国土交通)

After setting up the mics and starting the recorder, I covered the pack with a bandana.

Audio recorder and mics on backpack along Yasugawa in Iseochi, Ritto City, leaning on a stone marker by the Ministry of Land, Infrastructure, Transport and Tourism (国土交通)

Location

Bamboo groves line the left bank of Yasugawa in Ritto City downstream from just below the Meishin Expressway in Iseochi to the ground golf course in Deba (map).

Bamboo woods along Yasugawa in Iseochi, Ritto City

Bamboo and vines grow wildly in these unmaintained groves, and fallen trees lie in random patterns everywhere except in a few well-maintained sections. Unable to walk more deeply into the woods, I placed my recorder and microphones just inside enough to reduce the wind. To record the location I used Spyglass.

Great cormorant recording location seen with Spyglass on iPhone 7

About 30 meters upstream the view is much nicer from a cleared section, with Bodaijisan (菩提寺山) and the Meishin Expressway in the background.

Yasugawa at Iseochi, Ritto City, seen with Spyglass on iPhone

The riverbed extends to the northeast far back to an embankment along Minamizakura and Omifuji in Yasu City. It flows into Lake Biwa (琵琶湖) about 13 kilometers to the northwest.

Yasugawa (野洲川) and Mikamiyama (三上山) seen from Iseochi, Ritto City

Audio post-processing

Audio post-processing was done with Audacity on Fedora Workstation, a Linux system running on a Lenovo ThinkStation 20 computer. I trimmed this excerpt from a longer recording and raised the overall volume. I added a high-pass filter to one version of the output, but no other digital signal processing was done.