In the normal course of events free range chickens move around their territory as a group. The focal point of these groups is the senior rooster and the hens keep within earshot of the rooster in order to hear any warning calls he may give. There are occasions when a hen may leave this group. The most common reasons for a hen to leave the group is to lay an egg.
I have between five and three separate groups here which I call tribes. Each tribe comprises a senior rooster, four or five hens and possibly pullets and cockerels.
Like many people when I first heard the egg song I mistook it for an alarm call and would crash through the undergrowth alongside the hens rooster in an attempt to avert some imagined disaster.
Watching one particular long established pair, (Harold and Blue Spot) it became apparent that when Blue Spot made egg song call, Harold would rush to Blue Spots location with his wings outspread making making hysterical calls. As soon as Harold arrived at Blue Spots location Blue Spot would go quiet and the pair would often mate.
The Theory Through Observations
In a free range setting there are numerous possible egg laying sites. Here the tribes tend to roam over four acres so it’s quite possible for a hen to choose an egg laying site some distance from the tribe’s coop, or the current location of her tribe.
When a hen wants to lay an egg, she indicates this to the senior rooster and then starts to make a particular call (the escort call) that lets the rooster know she wants escorting to a laying site. The rooster then moves the tribe to a safe location and accompanies the hen to an egg laying site. If the egg laying site is already established the rooster escorts the hen to that site and then returns to the tribe. If it’s a new site, the rooster may accompany the hen to various locations, often suggesting a suitable site by scratching the ground and making nesting sounds and sitting in the site until the hen settles. Sometimes the rooster will hustle a hen off a particular site, I’ve assumed because he doesn't think the site is safe. Choosing a new site can take some hours and I’ve watched these pairs travel round various locations testing one site after another.
Once a site has been chosen and the hen settled the rooster normally returns to his tribe.
There have been occasions when the hen hasn’t settled at any of the sites the pair have visited and the hen runs out of time and lays the egg wherever the pair can find a site quickly. The rooster sits on top of the hen in such cases until the egg had been laid.
Once the hen has laid the egg in order to rejoin the tribe safely she calls for her rooster to escort her back to the tribes location. While the hen has been laying the egg the tribe may have moved to another location. Often the hen will move a short distance away from her egg laying site before she makes the escort call in order to make the egg site more difficult for predators to locate.
The best roosters I’ve known here respond to their hens escort call immediately, firstly by answering her call to let her know he’s heard her and secondly by making their way to the hens location quickly.
Once an egg site has been established given a hen is in a stable tribe, they don’t always call to be escorted to the egg laying site; but call to be collected from it.
Given the vulnerability of a single hen either laying an egg, or returning from an egg laying site, to advertise to any watching predators that she will be sitting unprotected possibly with a pile of eggs seems a suicidal strategy. Most of the hens that have been killed by predators here have been returning from an egg site unaccompanied, either because the rooster hasn’t responded to the hens call, or because she’s inexperienced and has moved from the egg site and the rooster hasn’t been able to find her.
Why This Works
The primary role of the rooster is to further his genes. Escorting his hen to her egg laying site means he knows where the hen is. When the hen gives the escort call it’s in his interest to mate with the hen at the earliest opportunity in order to fertilise the next egg and to guard the hen from other roosters who also want to further their genes. All the roosters here know what the escort call means and which hen is making the call. Rogue roosters have often used this opportunity of an unguarded hen to mate. My belief is it has little to do with guarding the hen from predators. The roosters motives are purely selfish and that may be why the system works.
I have a nest box in my house which all of the hens in Tribe 1 use and this gave me an ideal opportunity to test my theory.
1) Fat Bird, senior hen in Tribe 1 was the first hen to use this nest box. At that time Tribe 1 didn’t have a rooster. Once she had laid the egg she made the escort call. It took a few attempts but eventually she accepted me as the escort and when I arrived the call stopped and I would accompany her back to the other hens in her tribe.
2) Ruffles (Tribe 1 senior hen) uses this egg box and arrived with Tribe 1’s rooster Cillin to lay an egg.
I shut the door so Cillin couldn’t return to the tribe (he was fine) and when Ruffles had laid the egg there was no escort call. I’ve repeated this experiment with 6 hens now and if the rooster is within sight the hens don’t make the escort call.
This is Ruffles being protected by Cillin while she lays an egg. While this wasn't a new site, Ruffles hadn't laid here for a while because she had hatched chicks recently. The chick is still with her.
This is Cillin protecting Ruffles in a temporary nest site. Fat Bird was in the permenant site that day.
3) I carried Fat Bird to a location away from her Tribe and left her in a safe location but kept close enough to watch her. After a while she made the escort call and Cillin the tribes rooster responded vocally and then arrived and escorted Fat Bird back to her tribe.
4) Tribe 3 has a junior hen called Myth. Myth lays her eggs in the tribe coop. Because she is junior and not a favorite Notch Tribe 3’s rooster sometimes doesn’t answer her escort call. I waited for Myth to lay an egg and by closing the run under the coop, prevented her from leaving the egg laying site. She gave the escort call incessantly. I found Notch and carried him to Myth. Myth stopped making the escort call.
5) I removed Mel, hen from Tribe 1 to another location and after she had emptied my pockets of walnuts she gave the escort call. Cillin (Tribe 1’s rooster) was three hundred yards away with the rest of Tribe 1. It took him 57 seconds to reach Mel. Mel stopped calling when Cillin came into sight.
Through numerous such tests, with various tribe members, I believe that the egg song is in reality a call for a rooster.