I don't know if they are regular but when i went last week they were not there first thing, so maybe later in the day is better. Were your parakeets easy to find? I've never looked for them there but they keep being reported in Studland.
The Spotted Redshank and 2 Avocets have been around since November I think. When I have seen the Spotted Redshank it has usually been from Fisherman's Bank which is basically a path in front of the houses you can see looking towards Mudeford. Accessed by walking up the main road away from the car park towards Mudeford until you get to a gap in the houses where you can see the marsh. The Avocets can also be seen from there or off Crouch Hill which is the hill half way through Stanpit with a bench on it.
I think that the Bean Goose and the Greylags it knocks around with are best seen lunchtime through to early afternoon. There are quite a few groups of Greylag and they can be elusive in the furthest fields. I think the Bewick's was a wanderer from elsewhere in the valley and possibly isn't as regular. It was however quite close on the other bank (albeit with the Avon in between). Word of cautionthough the path is going to very muddy and wet. It was frozen over on Friday and the bits in between were mud so I guess by now it is quite a mud bath and wellies essential.
As Mark says the Bankes Arms and Middle Beach Car Park is the best bet for Parakeets. They have used a nest hole bang in the middle beach car park.
I think the best options are either the circular walk described around the paddocks or even better scan the bay for Divers and Grebes and wait for their screeching to alert you to direction and distance they are at. Even better in Summer if you need to keep that special person sweet. Treat them to pub lunch in the pub garden and watch them fly over (the parakeets not the wife, she never gets that excited especially by scampi and chips).
Can anyone give directions to Ferndown Common? I work in Ferndown and have tried a few places at lunchtime over the years. Tried Slop Bog recently. Nothing of note but I would love to get that name on the Pager.