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.
