New research reports a surprising courtship signal in scissor-tailed nightjars from northern Argentina. The study appears in the Journal of Avian Biology and was led by Christopher Clark of UC Riverside with Juan Ignacio Areta of CONICET.
Male nightjars perform a dramatic display with long forked tails, and observers had long heard sharp snapping sounds near the birds. To study this, researchers used high-speed infrared cameras during predawn hours, often near the full moon and sometimes between 3 and 4 AM, when ambient noise was low.
Video confirmed the snaps are not vocal. The birds strike the wrist joints of their wings so the radius bones collide, producing a clap-like noise; the paper notes a bird radius is roughly like a human forearm. The team checked museum specimens but found no obvious wrist modifications.
Clark’s lab studies unusual animal sounds and is exploring whether some wing noises might create tiny shock waves. The project began during a sabbatical in Argentina and grew because these nightjars were easier to observe than species deep in dense vegetation.
Difficult words
- courtship — behaviour animals use to attract mates
- display — a visible behaviour to attract attention
- predawn — time just before the sun rises
- ambient — background sound or general surrounding condition
- wrist — joint between hand and forearm
- specimen — individual animal or object kept for studyspecimens
- sabbatical — a long break from work for research
- radius — one bone in the forearm next to ulna
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Have you ever seen a bird perform a courtship display? What did it look like?
- Why do you think the researchers filmed the birds between 3 and 4 AM near the full moon?
- Do you think small wing sounds could be important for animal communication? Why or why not?
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