For the last several years Silvereyes have feasted on the fruits of Ruby Saltbush Enchylaena tomentosa at this time of year at my place on the s.e. slopes of the Mt Lofty Ranges SA. This fruiting season nary a Silvereye has turned up so far.
At the same time there has been a dearth of raptors & a big increase in House Sparrow & European Goldfinch numbers, the former doing the fruit eating. I'm not sure what the latter are feeding on.
My thinking is that the lack of raptors has encouraged the House Sparrows which are preventing the Silvereyes from moving in.
And perhaps the lack of raptors is also encouraging for the European Goldfinches.
Thoughts anyone?
I think sparrows only live with people so more sparrows must mean more people living in your area. Probably someone nearby has planted a vineyard and neglected to net it, silvereyes just love ripe grapes, I'm sure they will return when whatever fruit they have found to eat runs out.
Raptors, especially hobbies and sparrowhawks in particular love goldfinches so I'd say that could well be a factor in the population increase.
However goldfinches typically feed on introduced Asteraceae and Poaceae seeds.
GregL, we do have relatively new neighbours & there's a general increase in the neighbourhood population of humans. The new neighbours & a number of other locals are into horses which may well be fed oats lately in view of the pasture grasses having been eaten down to dust level on a number of properties. From what I've observed oats attract hordes of House Sparrows. But I'm unaware of any grapevines being planted. The terrain is too rocky & dry for vines.
Zosterops, the reduction in raptor numbers would seem to be an important factor in the population increase of Sparrows & Goldfinches. As you said, the latter may be attracted by the introduced ASTERACEAE species around the place. We get the occasional Sparrowhawk & the even more occasional Hobby but not for many months. I'm hoping that the increase in Sparrow & Goldfinch numbers will re-attract a raft of raptors to control undesirable numbers of small feral birds. I'm even wondering if raptor numbers have declined because mice numbers have been affected by the lack of rain over the last 8 months. However, I've noticed a lot more small lizards &/or skinks skittering throught the grass tufts so these creatures may compensate for the reduction in mice numbers.
Oh, what a tangled web is probably being woven!
Thanks to both of you for your thoughts.
I rarely see any bird-on-bird raptor action at my place. I once saw a falcon kill a galah and sometimes see currawongs steal nestlings but raptors here mainly go for terrestrial prey. Maybe the smaller raptors are scared away from farms so I don't see them in action.
I would be quite pleased if the silvereyes would disappear from my place, they eat all my cherries off the trees before they are ripe.