Goldfinches have visited my birdfeeder for ages, taking loads of food during the breeding season and at the start of winter. Sparrows have been gradually increasing in number as they get used to my garden. Now all the goldfinches seem to have gone and I have LOADS of sparrows! Chaffinches seem to be coming back as well, I think they were all bullied by the goldfinches
In my garden The House Sparrows are slightly more dominant than the Goldfinches, though the latter are pretty feisty. However both cede to the much larger Ring-necked Parakeets.
I'd be surprised if Goldfinches have deterred Chaffinches, as the latter tends to feed on the ground much more. There does seem to have been a big reduction in both Chaffinch + Greenfinch down here. So far this year visiting some of London's premier birding spots I've already seen just under 100 bird species this month, but I've only seen Greenfinch twice- 2 in my local park + 5 at feeders at the London Wetland Centre last weekend.
The goldies are starting to flock in the sycamore over the road again 'upwards of 50' not seeing any chaffinch here but plenty on my walks no greenfinchs seen or heard any where, yet there usually singing here by now and the only birds on and around the feeders are robin, house sparrow, dunnock, blackbirds and the ever present woodies no squirrel for a couple of days ian
I can't explain why your goldfinches have gone but I'd be surprised if the chaffinches have forced them away. Although the chaffinches are larger birds the goldfinches I see are feisty characters and seem to hold their own.
The change in the numbers of goldfinches in gardens is interesting. In our east London garden we never saw any until, probably, 8-10 years ago, when around 5 or so appeared at about this time of year and stayed until for about a month, but then disappeared. Over the intervening years more appeared and stayed longer. Now they are present all year and are the most numerous bird in the garden.
We have talked about how we will count them all for the next Garden Bird Watch.
I have chaffinches at the front of the (terraced) house, they use the street tree. They used the feeders at the back as well until the goldfinches turned up I have some feeder trays for birds that don't like the hanging ones and they preferred those, but I can't see the ones feeding on the ground due to vegetation! The dunnocks seem the most persistent, popping out of the hedge to feed. A pair of tolerant blackbirds have gone, now I have a timorous male and I have had a couple of glimpses of an even shyer female. I think I saw one greenfinch once. The goldfinches and the sparrows had some entertaining battles - I had been thinking of getting a second hanging feeder to spread the load until the goldfinches left. There is also a robin, great, blue and coal tits and woodpigeon. I feed seagulls, crows, magpies and jackdaws during the cold spell by throwing food on my garage roof I've tried counting the sparrows to practise for the birdwatch, at most I think it's 15 - 20.
edited as I forgot the starlings, and 2 goldfinches have just visited to prove me wrong