It is easy to dismiss the Blackbird as just another common, year-round garden resident, but there is more to this familiar bird than you might think!
Blackbirds were originally woodlands birds, but over the years have adapted very well to an urban environment. So much so, that it is thought that urban Blackbird populations may even act as boosters for less productive woodland populations, which face significantly greater levels of nest predation – despite all the cats in our gardens! The most serious threat to urban-nesting Blackbirds is probably a prolonged period of dry weather, which makes getting at earthworms in a rock hard lawn very difficult and puts their chicks at risk of starvation.
Breeding territories and feeding sites may be used year after year by socially dominant birds, particularly those with food available throughout the year. Blackbirds have a varied diet, not just feeding on fruit and earthworms, and have even been seen taking tadpoles and newts from the shallows of garden ponds.
Information from the BTO Garden BirdWatch reveals a seasonal pattern of garden use, with a reduction in numbers from August to October. This ‘autumn trough’ is probably linked both to the availability of fruits and berries in local hedgerows and to the post-breeding moult, when they become rather shy and retiring.
The Blackbird is one of a small number of species that sometimes sing during the night, particularly near to street-lighting. They have large eyes relative to their body size, and BTO research has revealed them to be the first species to arrive at garden feeding stations on dark winter mornings. Good vision in low light levels influences when a species is first able to move around and find food.
BTO research has also demonstrated that Blackbirds living in urban areas arrive at garden feeding stations later than those living in rural gardens. This seems to run counter to the influence of light levels on arrival times – since urban areas have more street lights; suggesting that temperature may also play a role. Urban areas have higher levels of heat pollution which raise air temperatures above those in the surrounding countryside, and as birds use their energy reserves to keep warm overnight, those in rural areas will need to find food more urgently in the morning.
Surveys have revealed that at least 12% of our winter Blackbirds are immigrants from mainland Europe, their arrival by the thousand during the autumn months going largely unnoticed; primarily because they look the same as those that are here all year round. However, an early morning visit to some berry-laden coastal scrub and hedgerows will reveal these immigrants feeding alongside newly arrived Redwing and Fieldfare. BTO bird ringers have shown that these winter immigrants originate mainly from Scandinavia, The Netherlands and Germany, some of which are just passing through, and will continue on south to winter in Spain, France and Portugal.
Being able to watch several Blackbirds at once helps differentiate between the various plumages, separating the brown females from the black males, and young birds (with some juvenile wing feathers still retained) from older individuals. Birds with one or more white feathers are often seen in our gardens, and are probably ‘leucistic’ this being due to a local absence of pigment cells.
If you find the lives of our garden birds to be of interest, and would like to join in and count the feathered occupants of your garden, please contact me or visit the BTO Garden BirdWatch website (www.bto.org/gbw). If you know of a local organisation who would like a talk on garden birds call: Mike Gray 07596 366342 or firstname.lastname@example.org.