Dear Readers, you might remember how much I love British Birds magazine, and in this issue there were two tales of misplaced parental responsibility that I found absolutely fascinating. The first came from Pauline Hogg and Phil Palmer, who were at the Fairburn Ings RSPB reserve when they noticed a Great Spotted Woodpecker nest in a tree. To their astonishment, they noticed a rather nervous blue tit coming to the nest hole, and feeding the well-grown woodpecker chicks. Furthermore, it quickly became apparent that the lucky nestlings were being fed by two blue tits, a great tit and their actual parents.
It was noticed that, on the second day, the woodpecker parents seemed to want the youngsters to leave the nest – they brought food but then flew away with it to a nearby branch, seemingly in an attempt to persuade the chicks to fledge. However, the blue tits continued to bring green caterpillars to the nest, and the great tit appeared to bring moths. The woodpecker chicks showed no inclination to leave that day, and I can imagine the adult woodpeckers tapping their feet and getting very irritated. Both the blue and great tits seemed very nervous when feeding the woodpecker chicks, as well they might – woodpecker beaks are big, and sharp.
We don’t know the end of the story, but by the time that Mr Palmer and Ms Hogg visited again, the woodpeckers had fledged and the tits had gone. One possible explanation is that the blue/great tits had nested in the old woodpecker holes in the tree, but that the woodpeckers had then eaten their nestlings – certainly great spotted woodpeckers are notorious for drilling into nest boxes and taking the babies. Could it be that the instinct of the parents to provide food was so strong that they continued to feed? It seems not unlikely, but I guess we will never know.
Another tale of misplaced parental enthusiasm was reported by Martin Garwood, who was actually looking for Purple Emperor butterflies in Dene Park, Kent, when he noticed a pair of pied flycatchers feeding well-grown youngsters in a nest. After a few minutes he went back to his butterfly-search, only to hear a kerfuffle by the nest. A song thrush with a beak full of invertebrates was attempting to feed the pied flycatcher chicks, with no success. Undaunted, the song thrush settled down to brood the nonplussed youngsters, while their parents tried everything they could think of to unsettle it. Eventually the thrush was disturbed by a passing cyclist but as it only moved a short distance away, I think we can guess that the same nonsense continued.
Was this a song thrush who had failed to breed, who had lost his/her own eggs, or who was just confused? Again, I suppose we will never know. What these two cases do point up, though, is the pressure that breeding birds are under, which can only be exacerbated by diminishing suitable habitat and continual disturbance. I sometimes think it’s a miracle that any birds actually manage to rear their young to adulthood. It also seems to me to be an indication of how complex the behaviour of birds is, and how little we understand it.