I live in northern Tasmania and each spring I eager
y await the blackbird song. This spring I have noticed a marked reduction in blackbird numbers in my area and much less blackbird song. Could this be a climatic issue?
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It is hard to say but sometimes conditions will change and birds will move elsewhere. There may be some ground-dwelling mammals or birds that have scared the blackbirds away, or they may have found a new source of food elsewhere. They will most proably return after a while with no explanation of why they moved elsewhere.
It'll be interesting to learn if the native Bassian Thrush occupies the ecological niche that the introduced Blackbirds previously occupied, annabower. Both species get their food from scratching around in litter & where there are Blackbirds you don't usually find the Bassian Thrush. Keep your eyes open for the Bassian Thrush!
I haven't noticed a decline in blackbird numbers locally (e of Melbourne) but have noticed a decline in House Sparrow, Tree Sparrow, Song Thrush and Starlings.
Whilst these are introduced species involved I would be interested to know reasons behind these declines (all birds are environmental indicators).
Yes one wouldn't expect the hardy introduced species to decline. I saw something on the telly very recently about research into sparrows to find out why they have been able to adapt to a wide range of conditions, including climate. The research was being undertaken in the interests of Australian native birds to assess how well they might cope with climate change.
The House Sparrows haven't been doing particularly well globally, especially in the UK (where they are actually not native) where there has been massive local declines, I believe a virus has been implicated at least in some regions.
The Red-whiskered Bulbul population in Melbourne died out in recent years (there have been recent sightings since though these may or may not have been more recent aviary escapees).
I would very much like to think that the fact that people are increasingly planting more native vegetation, has impacted on the numbers of blackbirds. That can only help native birds to prosper. On my property, where there is plenty of natural bush left, but urban development is close by (about 5km ), the balance hasn’t changed, and both species, Blackbirds and many Bassian Thrushes co-exist.
Nature is so dependent on what exactly grows where. As I am moving from the house into my shed soon, only 250m down the drive, the vegetation is so different that even in this short distance the birdlife is completely different too. When we moved into the house 15 years ago, we planted lots of grasses and shrubs for Honeyeaters. Now everything is happening around here. Down at the shed everything happens on the other side of the fence in the bush. Makes no difference to the birds though, just me. First thing I will do once I move up there, plant, plant, plant.
I listened to an interesting program on the ABC during the night, about the decline of the Indian Miner. Because Shopping centres have planted a lot of Gumtrees in their car parks, there has been a rapid increase in Lorikeets. (I certainly have noticed that around here) The Lorikeets have taken up the fight against the Miners and driven them out successfully . So , as you can see, it all depends on planting native vegetation. Nature can only fight back if given a chance.
M-L
Blackbirds have adapted pretty well to native vegetation. I've seen them in various national parks far from settlement though from my unscientific assessment they seem most common on edge type landscapes when human disturbance has allowed the proliferation of a variety of colonising plant species.
Indeed, Blackbirds serve as the main dispersal agent for weedy natives like Pittosporum undulatum, Billardiera heterophylla and perhaps some native Solanum species outside their natural ranges.
I've managed to confine Blackbird numbers to 4 at my place. Even tho' I eradicate their nests in spring & even tho' most of our vegetation is indigenous to our area these 4 persist. However, I have the strong suspicion that by planting habitat which favours native birds, particularly indigenous habitat, the Blackbirds & other feral birds are disadvantaged because native birds' survival chances are enhanced. But there can be little doubt, I would have thought, that planting exotic vegetation, particularly from the Blackbirds natural range in the northern hemisphere, would enable Blackbirds to proliferate in Australia. They survive best where there are exotic trees with dense undergrowth & this type of environment would be very common in most Australian towns & cities.
Araminta, that was most interesting information about how the planting of Eucalypts at shopping centres is believed to have led to a decline in Lorikeet numbers. Both Lorikeets & Indian Mynahs nest in hollows so maybe the Lorikeets are being very competitive with the Mynahs.
There's been a huge decline in House Sparrow & Starling numbers where I live on the s.e. slopes of the Mt Lofty Ranges, SA. The feed which the previous owners imported for their horses would almost certainly have provided food for the Sparrows (& thought) but I believe the presence of Goshawks due to our revegetation with indigenous species has been a factor in Sparrow numbers declining. I did hear, too, that changes in car exhaust fumes in cities has negatively affected Sparrow numbers but I don't know exactly how. See ww.wandsworth.gov.uk/info/745/biodiversity_and_wildlife/170/species/6.
I think proliferation of a variety of environmental weeds both exotic and native is due to Blackbirds essentially creating their own favoured habitat as they colonise areas. They seem closely associated with Pittosporum undulatum here (it has undergone a massive distribution expansion), and a range of exotics like Cotoneaster, Pyracantha, Solanum mauritianum, Ligustrum sp., Hedera helix etc. I've also seen them feeding on native Rubus spp.
I had thought that modern housing construction and development was removing a lot of old houses, holes in which had provided ideal nesting sites for House and Tree Sparrows. Though it does not explain why Common Mynas continue to increase, perhaps Mynas are utilising a lot of the remaining cavities needed by Sparrows and are outcompeting them (if so an interesting situation whereby an introduced species is being outcompeted by another introduced species).
I wish to thank all those who have responded to my post about blackbirds and have provided me with much interesting and relevant information. Birds are an important part of my life and I am aware that the blackbirds are not native to Australia and by many considered "feral". My European upbringing however, has endeared the most melodious song of the blackbird during the spring and early summer months to me, reminding me of my childhood. Thank you all.
Oooops! Sorry Araminta. I meant a decline in Indian Mynah numbers.
And if it's bird songsters you like then it's hard to go past Australia's Grey Shrikethrush, Golden Whistler & Rufous Whistler. However, I understand that being from Europe it's nice to hear a sound from home. But having reminders of England & other parts of Europe is precisely why we have so many feral pests in Australia which in so many case have outcompeted Australian species & have contributed or are contributing to their extinction. Sadly, that's the way it works.