canberrabirds

Paucity of Common Blackbirds

To: 'John Layton' <>, 'Canberra birds' <>
Subject: Paucity of Common Blackbirds
From: Philip Veerman <>
Date: Sat, 5 Oct 2019 08:58:34 +0000

An interesting observation from John. I have been thinking the same too. Certainly is well down in numbers around my place. Only occasionally seen recently, rather than the usual daily of years ago. The GBS Data is not so easy to track from the ABR but it certainly suggests a decrease. Last year’s Abundance: “down 54% on the 30 year average.” From the last ABR the species was ranked 31 on abundance. From The GBS Report it was ranked 15, although that is ranking on number of records. Quite likely dry soil conditions are the main cause of their decline. Harder to find worms and other invertebrates in the soil layer.

 

The info from The GBS Report is inserted here. The annual pattern as shown on the monthly abundance graph is quite smooth and variations through the year are so small that there is no suggestion from that, of altitudinal migration.

 

Common Blackbird Turdus merula

This is a species that is common and conspicuous. Males sing during the early mornings of spring time. At

any time the species’ clanking flight and alarm calls are easily detectable. This bird is at home in gardens,

either open lawn or amongst messy leaf litter, feeding on soil invertebrates and soft fruit. It has a very regular

monthly pattern, though with a minimal amplitude. There is a low in February then increases to a December

peak then decreases down to the February level. It is quite common to find dead adult males during the

midsummer heat, though that seems unlikely to have such a dramatic impact on the total numbers.

Abundance increased smoothly from Years 1 to 10 and then has only marginally declined over the last six

years, though the range has been small. As the species is widespread, this is clearly a true result.

This species is unusual in that the number of observations at the nest far exceed the number of observations

of dependent young. This is probably because it commonly breeds in well hidden nests in vegetation very

close to houses and dependent young are not especially conspicuous for long. Breeding records consist of

activities at nest over a broad period from mid August to late January and dependent young from mid

September peaking in December to late February.

Graphs on page: 105, Rank: 15, Breeding Rank: 6, Breeding graph on page: 107, A = 1.73186, F = 91.96%,

W = 52.0, R = 72.172%, G = 2.40.

 

From: John Layton [
Sent: Saturday, 5 October, 2019 5:58 PM
To: Canberra birds
Subject: [canberrabirds] Paucity of Common Blackbirds

 

Yesterday afternoon I saw a male Common Blackbird perched quietly on an electrical cable. This is the first blackbird I’ve noticed in our garden since early last winter.

 

Five weeks into spring, I would expect to see two, sometimes three males, pursuing each other helter-skelter through the garden almost every day and, on calm spring evenings, an hour or so before and beyond dusk, a dominant blackbird would occupy a prominent perch and regale the neighbourhood with a cascade of melodic notes. But not this spring. So where have they gone? Perhaps it’s too obvious to suggest they’ve moved to littoral areas where worms may be closer to the soil surface.

 

Incidentally, does anyone know if there’s published work on the movements of Common Blackbirds in s. e. Australia? I somehow suspect altitudinal movements in addition to drought related shifts. Other than HANZAB I’ve not found anything.

 

John Layton

Holt.

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