At every garden I visit just now, I am attended by one or two robins (Erithacus rubecula). They look and behave so much alike that, when there is just the one robin in attendance, it almost feels like the same bird is following me about from one garden to another. You read that male and female robins are identical, but this is not the case – there is a difference, but it is slight and because robins often stand side-on when they’re watching us, it isn’t easy to see. The difference is seen in what can be described as the ‘hairline' and is clearly shown in the linked photographs here; the female bird’s hairline is ‘V’ shaped and the male’s is ‘U’ shaped. You can make out the ‘V’ in the picture below (taken with a zoom lens from some distance away). Since the eggs are incubated by the female only, this makes the distinction clear.
During late winter and early spring, robins form pairs and this makes it easier to tell male and female apart. It was only a week ago, when a pair of mated robins were bold enough to stand facing me for some minutes, just a metre away from where I was kneeling, that the difference became truly obvious. One robin had a distinct ‘V’ hairline and the other had a much flatter ‘U’ hairline. The two birds watched every move I made as I weeded through a rockery, darting forward to pick up worms and insects and then moving back to keep their vigil a short distance away.
The habit robins have of following gardeners is age old and at one time, when there were fewer humans, they more often followed wild pigs to find the food unearthed by the pigs' foraging snouts. This is called ‘commensal feeding’, with humans being the ‘beaters’ and robins being the ‘attendants’. It isn’t confined to robins, either; think of the gulls and crows that follow the farmer’s plough. Blackbirds do it as well – there have been many occasions when I’ve dug a planting hole, gone to pick up the plant and returned to find a blackbird in the hole, busy finding worms.
Robins are extremely territorial and their behaviour towards each other outside the mating season is hostile, sometimes resulting in fights to the death, but during late winter and spring they make charming company for gardeners. Some are restless, flitting from branch to ground, others will sit in a nearby shrub and sing their quiet, wistful sub-song. The reason for sub-song is probably that they are singing to themselves, but it is easy to hold the impression that it is sung for us alone, for surely no other bird could hear it.
From ‘Address to a Robin’
Come, sweetest of the feathered throng,
And soothe me with thy plaintive song;
Come to my cot, devoid of fear,
No danger shall await thee here…
Hop o’er my cheering hearth, and be
One of my peaceful family
Then soothe me with thy plaintive song,
Thou sweetest of the feathered throng.
Edward Jenner (1749-1823)