Birds and bees eat nectar and pollen and so the trees get pollinated. However it is just a little more complicated than that. I have been watching my bees taking Grevillea flower nectar to make bees honey and lorikeet parrots supping it to fuel their high speed life style. The Grevillea allows the nectar to flow and the roaming birds find it during the check of their territory. Scouting bees smell it out and communicate via the wiggle dance to the rest of the nectar and pollen bee gatherers in the beehive. The bush then turns the nectar feast off to allow other bushes to have the pollinators and have a rest to build up nectar reserves for the next feast. This happens a few times a day. Nectar is turned off at night unless nocturnal pollinators like bats and moths are about. During bad weather nectar flow is stopped as it would be wasted and washed away, and the birds would be in their roost and bees in the hive eating bees honey.
So the birds, bees and trees depend on each other for their survival and seem to be excellent at it. This interdependence indicates communication between plants. Wonder if nectar turn on and off is at same time or random????
Observations by the bee whisperer 26/7/20.