By James Duncan
Learning and Engagement Officer
In this series of blogs I'm going to be exploring the wonderful world of bird song (with calls thrown in for good measure!) There's surely little more calming to human ears than the annual serenade of spring song. Each day, prior to the sun's appearance above the horizon, birds begin to advertise their presence, demonstrating their strength and ability in song. This serves not only to attract a mate but also to deter rivals. As you wake in the morning, during these times of increased isolation, take a moment to notice the birds who break the morning silence, the Robin, the Blackbird and perhaps the Song Thrush. Enjoy the chorus as it widens, as Wren, Starling, Chaffinch and Dunnock join in. The complexities of bird song may not be easy to get to grips with, but why not take the time to learn. The satisfaction to be gained from identifying birds by song (and calls) really can't be overemphasised - it's truly a window into another world.
4# Blackbird (Turdus merula)
Next up, the Blackbird, whose song is perhaps more familiar to us than any other. Indeed, not just the song as the Blackbird is surely the species we associate most closely with our gardens. In truth its distribution is as widespread as the Wren, occupying all manner of habitats, though the densities thin out as altitude increases towards Scotland's highest peaks. Its adaptability has certainly helped it to thrive, having unquestionably taken advantage of living alongside us. Blackbirds residing in urban areas seem to live at vastly higher frequencies than those in rural areas. This aside, it's important to note that Blackbird populations have seen substantial fluctuations in recent years, including a decline of over 15% since the 1970's. Recent surveys seem to suggest numbers may now be stable, and at this time it's the only member of its family, the Thrushes (Turdidae), that isn't currently on the Red-list of highest conservation concern. Unfortunately it has undoubtedly suffered from changes in agricultural practice, though not to the extent of other birds more typically reliant on such habitats. Though we have more than five million pairs in Britain, don't be surprised to see substantially more individuals during winter. Our temperate climate dictates the majority of Blackbirds are resident all year round, but in the colder parts of Eastern Europe and Scandinavia it's a breeding summer visitor. Many of these birds will opt to fly to Britain in autumn and stay until spring, perhaps doubling or even tripling our resident population.
The Blackbird is undeniably one of our most prolific singers, a bird with a gloriously varied vocal repertoire. Its 'fluted' carefree song, almost in major key, indisputably ranks it as one of the UK's favourite songsters. Indeed, the Blackbird appears to display a remarkable aptitude for both mimicry and learning. Ultimately the song serves two main purposes - to attract a mate and to ward off any potential rivals. A song of greater depth, contrast and variety is undoubtedly a benefit and may be the difference between successful and unsuccessful breeding. To that end, Blackbirds show a capacity for mimicking not just other birds, but even those sounds created by humans and our technology. There are a multitude of well documented cases of imitation and incorporation of sounds ranging from human whistling to car alarms. Adapting song in this way may well offer a competitive advantage. Perhaps the most astounding thing is the Blackbird may do this spontaneously; listening, learning and copying whilst developing their song. There's little doubt that renditions of human sound certainly strengthen our affinity toward them.
Blackbirds sing most typically during the breeding season, from March through to July. Song will be undoubtedly be heard earlier than March though it's not usually the full-fat version, but subsong, a version uttered by both juveniles and adults outside of the breeding season. It may well denote birds with a low sexual impulse. The breeding song is full of panache, a polished performance with smooth, mellow tones delivered at a slow tempo. In terms of closeness to its other family members, it's by far and away resembled most closely by Mistle Thrush. Blackbird song, however, is certainly more melodic with notes that dance along a wider scale.
Listen to the song in this video below -
Verses in the song tend to be relatively short, lasting approximately three seconds, whereas the pause between verses can vary from between three to five seconds on average. A great way to distinguish Blackbird and Mistle Thrush song is through the scratchy, twittering conclusion to the Blackbird verses. These may not necessarily be appended to each and every segment, but they help to give the song a less desolate tone. It certainly sounds passionate and richly complex, seeming to suit a warm summers' evening better than any other. The variety exhibited by the Blackbird is ultimately determined by its age and stage of breeding, but the capacity for learning and adapting the song will continue throughout its life. In a similar fashion to Eurasian Wren, studies have shown that some urban Blackbirds may well be changing their vocabulary, adapting to an evolving aural environment of increased intensity by singing at higher frequencies.
Where the song displays considerable variation, the call vocabulary also shows a lot of diversity - the Blackbird may be regarded as a noisy, easily agitated bird, unsettled at the merest hint of incident. It's worth noting that owing to their call complexity the examples below are not exhaustive and indicate a selection of what you may hear.
One of the most regular is the deep "pok" call. It sounds almost reminiscent of a subdued and somewhat stifled dog bark. It's often used by the Blackbird as an anxious low-grade call, particularly to warn of the existence of a potential ground predator. You may well hear this should you happen to approach Blackbird young too closely. Listen to this call below -
When suffering agitation Blackbirds may exhibit a fine and remarkably Robin-like "siiih" which usually has a slightly raised inflection in the middle of the note. It has a harmonious, wispy, high-pitched quality and is a typical alarm call expressed in similar fashion by other species. This is owing to the nature of its delivery which makes it very hard to locate, keeping the bird out of immediate danger. This may serve as a useful early-warning signal, particularly for potentially lethal predators such as Sparrowhawk, though may also be used when the nest is in close proximity. Listen to this call below -
A slightly more urgent and more widely recognised alarm call is the characteristic "pli pli pli", or "chink chink" depending on your perspective. This is a very insistent note (frequently observed), for the Blackbird will often call from an exposed position with tail cocked, wings drooped and body rippling from every explosive note. It's uttered for all manner of aerial threats, though in particular owls, crows and domestic cats, where the note may be repeated tirelessly as the caller faces the predator. The stature of the caller denotes a level of pent-up aggression and it's possible the call might be used to incite mobbing behaviour amongst other Blackbirds. Listen to this call below -
Unnerved by all manner of predators, Blackbirds also seem positively upset by the prospect of impending darkness. Roosting time has them calling nervously and when one starts it quickly fires up a whole host of others, a repetitive and obviously unsettled chorus. The call itself is almost identical to the typical "pli pli" ("chink") mobbing call, displaying a sharp metallic edge to the 'yapping' notes. It may perhaps serve multiple functions as either a direct territorial warning or perhaps a dishonest alarm useful for keeping other Blackbirds away. Listen to this call below -
A call familiar to anybody who has disturbed an unsuspecting Blackbird is the full-scale rattling alarm call, a combination of notes ramping up to an overwhelming crescendo, typically exhibited when the bird explodes from cover and takes flight. This call may begin with a more restrained "tuk-tuk-tuk" which when linked with the diagnostic "pli pli pli" can be rather surprising in both volume and intensity. It often returns to "tuk-tuk...tuk" as the call rapidly decelerates toward the end. Listen to this call below -
There's another call, faintly similar to the thin "siiih" alarm call, and it's one that's often carried out either during flight, or just beforehand. It's often heard from migrating birds and is hence the common flight call. It's 'trilling' in nature, with a thin, rolling 'r' and can be transliterated as "srrii." Listen to this call below -