Aggressive Pied Wagtail Issue

Hi all

I having an issue with an aggressive pied wagtail that comes into my garden.

He seems to be attacking any other small birds that tries to take food from the ground feeding table.

I read online last night that wagtails claim a territory and then aggressive patrol the area to prevent other birds from taking food from their claimed territory.

I have a metal ground feeder cage over my feeding table to prevent bigger birds from taking food from the ground feeding table.

The wagtail was inside the cage yesterday standing on the ground feeding table and every time this starling tried to come through one of the holes on the cage, the wagtail would charge at him to drive him back so he couldn't come through and take food from the table.

I have a Robin who turns up regularly but since this wag tail has turned up, the wag tail attacks the robin as soon as the robin gets anywhere near the table.

My worry is that the Robin won't survive the winter as he rarely has a chance to take food from the table.

Even when the wag tail isn't on my garden, he's normally on my neighbours fence, other times i can't see the wag tail yet as soon as the Robin gets near the table the Wag Tail appears out of nowhere so he must be watching from afar.

I just wondered if anyone has experienced this before and if so, was there anything you did that resolved this issue.

I'm getting concerned for the Robin's chances of survival if this keeps up.

Thanks

Dave