Last week I described how I had watched a treecreeper feed its fledglings. I had a letter from Mr Corby, of Long Marston, who described something more unusual. He had seen a robin feeding two fledgling wrens. Two wren fledglings had crash-landed, one into a bush and the other to the ground. Immediately, a robin, which was perched on a fence nearby, became agitated, flew down to the wrens and back to the fence. Both wrens then flew to the robin and, in turn, begged and were fed. I have records of robins adopting spotted flycatchers and song thrushes, wrens adopting blue tits and great tits adopting wrens. It may be that fledglings become separated from their parents and are found by an adult of another species that has lost its own brood but retains the parental instinct. The urge to feed begging youngsters is so powerful that a wren has been seen to enter a nest-box to feed blue tit nestlings. But there is a still stranger story of fledgling wrens entering a willow warbler's nest; the parent willow warblers fed both broods. The most ludicrous situation, however, arose in a dunnock nest which had been usurped by a cuckoo. The young cuckoo was enjoying the undivided attentions of the dunnocks, having thrown out their eggs, until it was joined by a brood of wrens from a nearby nest. They sheltered under the wings of the half-fledged cuckoo, which by now had lost its urge to eject anything from the nest. And on 1
November 1997 Last
summer a reader wrote to me about a pair of robins that
helped rear a family of wrens. This sort of behaviour is not
unknown but is unusual. This account was particularly
interesting because it showed how birds of one species came
to adopt the family of another species. The robins were
nesting inside a garage to which they gained access through
a small window. The wrens were nesting in a tit-box beside
the window. Sadly, the robins' nestlings died, one by one,
but the parents then started to feed the young wrens. Parent
birds are stimulated instinctively to stuff food into the
brightly-coloured, gaping mouths of their offspring. It is
easy to see how, when the robins lost their own young, the
instinct could be transferred to the wrens begging very
visibly at the entrance of the tit-box. The adult wrens
accepted this benign intrusion and it was not unusual to see
a robin and a wren at the tit-box together. Such was the
strength of the attachment that the robins assisted when it
was time for the wrens to fly. They joined the parent wrens
in calling the youngsters out of the nest and flew at my
informant in an effort to drive him away. The young wrens
flew out of the garden and were never seen again but the
robins returned. I assume that the behaviour of the two
species was too different for the robins to continue caring
for their adopted family.
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