Saturday 6 February 2021

Hull urban birds. 6. Mistle Thrush


The Mistle Thrush is a plump bird, larger than a Blackbird. It has a grey-brown back, a spotty chest, with round dark spots. The face is marked with white. The white tips of the tail's outer feathers are quite distinctive as the bird flies away. Males and females look alike. Unlike its relative the Song Thrush, it is quite bold, favouring the top of large trees (or aerials!) as singing perch, and often feeding in open grass, standing quite straight, away from cover. It is not unusual to see paired birds or small flocks outside the breeding season in the winter, feeding close to each other on the grass in milder weather.

Mistle Thrushes are widespread resident breeding birds in Hull, favouring parkland-type habitats: open grassland with mature trees, such as cemeteries, parks, churchyards, school grounds and playing fields.

Mistle Thrush using a headstone as look out post, 30 April 2020, Western Cemetery.

Berry tree guarding

In the autumn and winter Mistle Thrushes can be extremely site faithful, associating with particular berry-bearing trees and bushes such as yew, holly, rowan, ivy, hawthorn, mistletoe or whitebeam. Single birds - or sometimes a pair - defend their trees zealously and noisily with their rattling call and tail and wing flicking, and will chase away other birds, including thrushes, Woodpigeons, Waxwings, or bullfinches. Mistle Thrushes uses this resource as a winter food store, and will feed on it only occasionally, using other nearby resources if available. This 'resource guarding' behaviour can be very effective, and a tree still with berries in January or February is testament to the efforts of a guarding Mistle Thrush. As Barbara and David Snow said 'the presence of fruit on a holly or hawthorn after a certain date was an almost infallible sign that it was being defended by a Mistle Thrush'. The guarding bird can sit for long periods on another tree or perch overlooking the fruit tree, only to fly to the tree calling as soon as an intruder arrives to attack and drive it away. The guarding behaviour may collapse, though, if flocks of birds descend on the berry tree.

A Mistle Thrush guarding rowan berries, 14 Nov 2016, East Park.
This pair of Mistle Thrushes look on from a the street lamp while a flock of Waxwings feed on their defended rowans, 5 January 2019, Sainsbury's Way, Hessle.
Singing Mistle thrush, 9th December 2018, Pearson Park.

Breeding Mistle Thrushes

The Mistle Thrush is one of the earliest singing birds in the season, often already in December, and one of the earliest breeders. They will sing from a high perch even in poor weather. Breeding pairs are widespread around Hull: Queens Gardens, Northern Cemetery, Pearson Park, East Park, Pickering Park and Oak Road Playing fields hold a pair or two.

Individual collecting nest material, 17 April 2014, Pearson Park.
 
 Adult carrying food, 19/04/2020, Queens Gardens.
Adult feeding young, 9th June 2014, Pearson Park.
Adult carrying worms, 14 April 2015, Pearson Park.
Recently fledged young, Queens Gardens, 8/5/2020.
Worm-hunting Mistle Thrush poised to strike, 25 March 2014, Pearson Park.
Conservation concern
At the turn of the century, the Mistle Thrush was not a bird of conservation concern, but their populations have suffered recent breeding and wintering declines and it was upgraded to the 'Amber' list and more recently to the 'Red' list in the UK. Low juvenile survival might have contributed to this decline, but the reasons behind this are unclear and more research is needed. 
This clip shows a Mistle Thrush defending a clump of rowan berries at East Park, 14th Nov 2016.

More information
Snow, Barbara K. & Snow, David W. Long-term defence of fruit by Mistle Thrushes Turdus viscivorus. Ibis 126, 39–49 (2008).
BTO Bird Facts. Mistle Thrush.

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