When roosters crow at the break of dawn, their sound output is quite prodigious, reaching as much as 140dB levels at very close range. If you get that close, you can damage your eardrum in less than a second. But at even moderate distances, levels can reach 100 dB, close to the levels of a chainsaw. So the question arises as to why roosters do not become deaf from their own sound output. Christie Wilcox writes that scientists intrigued by this question have investigated and found the reason.
Loud sounds (above 120 decibels) can cause permanent hearing losses because the intense air pressure waves can damage and even kill the cells that translate sounds into neurological signals. At more than 130 decibels, it takes less than a second to inflict lasting damage. So you’d think that roosters crowing every day would slowly squawk themselves to total deafness. Since they don’t, scientists figured they must have some way of protecting their ears when they crow.
So researchers from the University of Antwerp and the University of Ghent in Belgium studied the ears of hens and roosters. They strapped microphones to three rooster heads, placing the business ends right at the animals’ ear openings, to measure the sound levels the animals experience when they crow. They also measured the crowing from different distances away. They then made micro-CT scans of hen and rooster ears to reconstruct the geometry of their ear canals when their beaks are open and closed.
The rooster crows they measured were more than loud enough to be potentially damaging—often over 100 decibels, and one animal in particular crowed at over 140 decibels. When the researchers looked at their ears, they saw how the animals are able to be so loud without going deaf: their ears are blocked when they crow. When the animals opened their beaks fully, their external auditory canals completely closed off. So basically, roosters have built in earplugs.
That’s pretty fascinating. I began to wonder why roosters crow in the first place and why they do it at dawn and it appears that researchers have found reasons for those as well. It turns out that roosters have an internal clock governed by circadian rhythms that enable them to anticipate the arrival of dawn. The reason they crow is to mark out their territory and warn rivals away. There is also a strict hierarchy among roosters, with the most dominant one crowing first and the others following later. If the dominant one is removed, then the second in line steps up to take the lead.
I once stayed at a B&B where the hostess conveniently forgot to tell me he neighbor had roosters. It was summer and dawn was early. I learned, what I had not know, roosters do not crow once at dawn, they keep on crowing for an extended period. They may not go deaf but I began to wish I was!
In the island of Kauai (in Hawaiian islands), some chicken have escaped into wilderness and -- in the absence of predators -- have spread EVERYWHERE in the island and have become wild/feral. They crow ALL THE TIME! My daughter captured a beautiful video of one of them crowing around mid-day, but can’t seem to locate it.
This is similar to how bats that use sonar aren’t deafened by their high frequency calls, only with bats the hammer and anvil bones in the ear are pulled apart as the bat emits each call, so the vibrations don’t travel to the drum.
Ok, so a rooster opening its beak to crow blocks its own ears. So, how come all the other chickens aren’t deaf?
They looked at that too. The volume gets decreased rapidly with distance so even at 50cm it drops to about 100 dB. So the chickens won’t go deaf but I’m not sure they enjoy it either.
Since it sounds and looks nothing like cawing, why do we call it “crow”ing?
RationalismRules
how come all the other chickens aren’t deaf?
Inverse square law.
Chickens try not to be too close to a crowing rooster.
Pierce, no.6; at a guess I’d say that crowing in this instance is used in the context of loudly showing off and asserting position rather than literally sounding like a crow.