Are blackbirds playing a part in thrush demise?

[Madelinew]

I counted 13 blackbirds in a space a little smaller than a tennis court in my garden this morning. I realise some of these may be migratory. However, in between scrapping amongst themselves, they spend a lot of time chasing off thrushes who are competing for the same food sources.

Now I keep all my bird feeders very well stocked and have lots and lots of places for slugs and snails so why are they quite so aggressive to the thrushes?

And is it my imagination or has the blackbird population increased quite significantly?

If so, how much are their aggressive feeding tactics contributing to the demise of the thrushes already affected by modern gardening methods?

Mind you they do make me laugh. They seem to exert far more energy protecting a food source than actually eating it.

[Rob_D]

I hope not! I have noticed alot of blackbirds this winter, but I understood that was because of a large number of migrants escaping the cold weather. Had a song thrush belting out yesterday evening on the roof, but he got chased away by another song thrush.

[Pippa]

Blackbirds don't hurt the Thrush population at all.

The reason they attack them is simply because they enjoy the same food

[aeshna5]

I think in the context of small gardens Blackbirds may have an effect on Song Thrush numbers here as they are a more domineering species, often competing for the same food items.

[lovfinion]

Blackbird may well bully Song Thrushes, but doubt they have any impact on their numbers, as for Mistle Thrush think they'd be the ones doing the bullying to a blackbird

[gillwrig]

I've notcied the same thing ... 10 in one tree. It was a bit like that hitchcock film here today as they were all looking at me!

They love those fruit flavoured suet pellets.

[Pippa]

Originally Posted by gillwrig

I've notcied the same thing ... 10 in one tree. It was a bit like that hitchcock film here today as they were all looking at me!

They love those fruit flavoured suet pellets.

Good to see the Blackbirds doing so well.

I actually saw a Blackbird and Thrush in conflict today but because the area was quite large,they appeared to beg to differ.

[squishy]

they come in from europe at this time of year. song thrushes do well, and mistle thrushes never have trouble asserting themselves!

[Pam_M]

The Blackbirds numbers have doubled in my garden this winter! Half are more than likely migrant visitors! Not often that I get a Song Thrush in my garden but when they do come the Blackbirds do get very territorial but the Song thrushes usually manage to get to the food eventually.

[Nightranger]

It varies from year to year but as discussed, many of the blackbirds you see at this time of the year will be migrants from continental Europe. Ironically, the aggressive blackbird individuals may be the local breeding birds because the migrants tend to be more tolerant of each other. This is because they do not hold territories here and aggressive behaviour is a waste of energy unless to do so would be critical to survival. Blackbird territorial behaviour is quite complex and boundaries can be fluid even in the breeding season to the point that nests can end up being displaced and destroyed by the new territorial owners. To further complicate things, blackbirds sometimes adopt communal feeding areas where there is a certain amount of tolerance over each other. However, the continental visitors simply descend wherever food is available and this is likely to be in an established resident pair's territory. The end result is that the territorial birds can become aggressive towards just about any bird of a similar size or smaller (robins and dunnocks can also be targets). They will even chase away mistle thrushes if the target individual is not similarly aggressive and collared doves. Everything tends to even out by the breeding season and because some of the winter song thrushes are also likely to be migrants, we can be sure this is not a factor in song thrush decline. Having said that, song thrush populations are increasing slightly and it is possible that the better fortunes are through an increase in the non-migratory birds now that they have less competition from the summer migrant element.*

*Three elements are seen in song thrush populations in the UK:

Summer migrants that breed in the UK but winter in southern Europe or North Africa these birds have suffered heavy losses to hunters in the Mediterranean region.

Resident birds that breed in the UK and stay throughout the year only making local nomadic movements in response to food and weather. This elemant was possibly smaller than the summer migrant element until the latter was much reduced.

Winter migrants that do not breed in the UK.