Black-crowned Night Heron is one of the species that fascinated me from early childhood on. But many years passed before I heard its typical qwar in the night for the first time consciously, during that same Bulgaria visit in 2014.
Despite sometimes being compared to a frog’s call, the qwar call is actually quite pleasing to my ears. It is situated between Eurasian Bittern and Little Bittern NFCs in pitch (mean frequency 1.5 kHz, n = 106), which is roughly comparable to Grey Heron. It sounds, however, more similar to Eurasian Bittern’s graow. If you are not confident to distinguish between Black-crowed Night Heron’s 1.5 kHz and the 1.1 kHz of Eurasian Bittern, you should listen for a more nasal sounding qwar with a rather questioning open end. It rhymes with “what” or, as if surprise meets with disbelief, just “wha?” so it sounds rising in pitch.
Black-crowned Night Heron Nycticorax nycticorax, Potistika, Argalasti, Greece, Greece, 02:14, 3 September 2017 (Lukas Pelikan). A series of qwar calls of a bird coming closer, loudest at 1:26. Background: rustling leaves, bats, dogs, crickets and a party.
The shape of the night heron’s call is often an arch but appears every so often merely as an almost straight line. There is an example for this flat type among the seven variations below (6). Compared to Eurasian Bittern the emphasis is more on the rising part, the beginning, which is what makes it sound questioning. You could even say it sounds like a backwards, higher-pitched rendition of Eurasian’s graow. Additional croakiness can appear as well, which blurs it all together. Further loss of sound quality makes it look rather complex and unspecific concerning shape. However, one distinct feature which many flight calls show in sonagram is a rather abrupt step down (sometimes followed by a step up) in the arch or line.
Black-crowned Night Heron Nycticorax nycticorax, Besh Barmag, Siazan, Azerbaijan, 21:47, 4 October 2017 (Jonas Buddemeier). A long series of qwar calls.
Black-crowned Night Heron Nycticorax nycticorax. Seven variations of qwar calls. 1) and 2) Potistika, Argalasti, Greece, 02:14, 3 September 2017 (Lukas Pelikan), 3), 4), 5) and 6) Besh Barmag, Siazan, Azerbaijan, 21:47, 4 October 2017 (Jonas Buddemeier), 7) Besh Barmag, Siazan, Azerbaijan, 22:37, 17 October 2017 (Jonas Buddemeier).
