Ilkley North West Trail #4: Virtuoso Vocalist . . . and Snail-Smasher!
This is the 4th of a 13-cache series which takes you on a 4.3km trail around some of the lovely countryside between Middleton and Austby immediately to the northwest of Ilkley above the north bank of the Wharfe. Allowing for an easy pace, stopping for caches | to admire the view | spot birds the trail should take you about 3 hours or so.
See GC8Q381 Ilkley NorthWest Trail #1: Intro & Start for background info on the trail and parking waypoints. See Gallery for a map of the trail showing parking spots and approximate cache locations.
The cache, a 35mm film canister, is hidden in a lovely shady grove of huge oaks. This is just off the trail as it heads on from #3, out of the Owler Park woods, across and down a grassy field past the grove, over a beck bridge and back into the fields above Low Austby.
The song thrush (Turdus philomelos) is a familiar and popular garden songbird whose numbers have declined markedly on farmland and in towns and cities. It is smaller and browner than a mistle thrush with smaller arrow-head spotting. See here for a useful video distinguishing between the two.
The specifies name is from a character in Greek mythology, Philomela, who had her tongue cut out, but was changed into a singing bird. Her name is derived from the Ancient Greek Φιλο philo (loving) and μέλος melos (song).
Its distinctive song with repeated musical phrases, distinguish it from singing blackbirds, and has frequently been referred to in poetry - listen here. An individual male may have a repertoire of more than 100 phrases, many copied from its parents and neighbouring birds (see here). Mimicry may include the imitation of man-made items like telephones and alarms. See here for a fascinating video with slowed-down audio - some extraordinary sounds!
It is omnivorous but especially likes to eat snails. It has the habit of using a favourite stone as an 'anvil' on which to bash snails with a flick of the head to break open their shells - see here.
It is mainly solitary but may form small feeding and roosting 
groups at good sites, and those that migrate gather in large but loosely co-ordinated flocks.
It establishes a breeding territory in the late winter or early spring. This is essential for pair formation and nesting, but only part of the food for the young is obtained from within it.
Territory size varies with habitat from 0.2-6+ hectares, but boundaries break down in the late summer when the last brood has fledged. Most of those in the UK stay in the same area throughout the year.
Winter territories are often established in the late autumn or early winter depending on weather and food availability. Many males remain in their previous seasons territory, and a few females hold individual winter territories.
They are sensitive to hard winter weather and territories are abandoned during periods of bad weather, when many birds move south, even as far as NW France and northern Spain. Many of the Dutch birds spend winter in the UK.
It has 2-3 broods a year (often using the same nest) so the breeding season is long, lasting from March to August. Onset of breeding depends on the weather which can bring it forward or delay it by several days.
The nest, which can take 3 weeks to complete, is built only by the female low down in any suitable cover, including trees and shrubs, among creepers on walls, on ledges, and on the ground amongst thick vegetation. It is a neat structure of twigs, grass and moss, cemented together and thickly lined with mud, dung and rotten wood, often mixed with leaves.
It lives for 3-4 years, but some survive much longer- the oldest known in the wild was 13 years 9 months old. Mortality is high with many and varied causes - only 20% of fledglings and 60% of adults survive to breed the following spring.
The English population declined by over 50% between 1970-1995 particularly on farmland - 70% leading to it being red listed as a bird of serious conservation concern. Since then there has been a partial recovery.
The decline is most likely due to loss and degradation of preferred feeding and nesting habitats. Loss of 
hedgerows and wet ditches removed feeding and nesting sites, while increased land drainage and tillage probably reduced the number of earthworms and other crucial invertebrate prey available on farmland.
Grazed permanent (especially cow) pastures and woodland are important habitats with plenty of food for song thrushes. Both of these have been lost or degraded in many lowland areas.
See here for more info on this tuneful but threatened bird.