Avicide in thrushes
P. F. Whitehead
I was fascinated to read the account (Cundall, A., 2010, Worcestershire Record 28:17) of one Fieldfare killing another. This is a really rare observation with few text citations and none given by Norman (1994), The Fieldfare, Hamlyn Species Guides). It certainly warrants explanation. At the discretion of the editor, and since it has a direct bearing on the Fieldfare observation, I should like to briefly relate an identical observation concerning Blackbirds Turdus merula L. in Lancashire. Although briefly cited by Hardy (1966), Merseyside Naturalist's Association North-western Bird Report 1963-1966, p.46) it has never been properly documented.
In one of many large contiguous suburban gardens in the Childwall area of Liverpool, backed by a 20 acre green field, Blackbirds were ubiquitous in the 1960s and formed a big roost in ancient woodland near Childwall village. Some maintained territories year after year and in March 1963 one such venerable male bird paired with a female, but failed to sing well and generally lost lustre, although the female built a nest. One day near the end of March the pair were joined by a third adult white-headed male and something of a 'ménage-a-trois' ensued. It is thought that this white-headed bird may have mated with the resident female at this time, further disrupting a somewhat weakened pair-bond.
During the morning, the white-headed male attacked the old male with force, pinning it down and pecking at the cranium, and holding it by the neck in its beak. I (misguidedly) intervened and 'rescued' the old male which had a number of significant injuries, including a badly damaged leg, but still accepted food. The maxilla was slightly overgrown from age. What was striking at this time was the fixated behaviour of the 'new' male. As the injured male rested on the inside sill of a window bay, the 'new' male repeatedly engaged in 'fly-pasts' and paraded to and fro on the outside of the sill.
In the evening I made a conscious decision to release the old male. What followed was a prolonged onslaught in which the old male was eventually despatched by repeated pecking to the head despite its penetrating vocalisations. The female, attracted by the cacophony, merely observed. After nightfall, the new male, ensuring that its 'rival' was now completely lifeless, flew to a fence where, in a notably long, loud and flourished 'victory' song it pronounced itself to be in command.
I do not wish to take up further space with explanations for these rare observations, which can be deduced, other than to say that the normal submission and threat signals, so evident in social turdids, were never observed by me. Additionally, like Cundall's observation (op. cit.), this one came after a hard winter.
CUNDALL, A., 2010, Homicidal fieldfare. Worcestershire Record 28:17
HARDY (1966), Merseyside Naturalist's Association North-western Bird Report 1963-1966, p.46)
NORMAN, D. 1994 The Fieldfare, Hamlyn Species Guides