Head through the gate into the Preserve Dockyard. Fight your way to the South until you reach the far end of it. At that point, turn East and start up the stairs to the North. After that turn to the East and head into the Holding Pens.
Drop down to the ground below using the gaps in the fencing or the fencing itself. Down there you have a number of Skags to deal with. Quickly attend to them and start to the Northeast. Climb on up the pipe into the observation room and deal with the pair of skags there. Cross through it after that. Time for Stalkers!
Continue to the Northeast toward the dome in front of you. You have a lot of Stalkers to deal with. Head up the slope to the North. There is a chance you will run into some Mini Bosses here: Tumbaa and Pimon. Just ignore or kill them and rush for the door below the Hyperion sign. Use the button to the right of the door to open it up and gain access to the next part of the Preserve.
Head over to the left and go on up the stairs on your right. Keep going to the North into the Dome. Deal with the Stalkers in the dome. From there make your way around the fallen beam and then go over to the West. Once there head on up the slope into the next open area. Here you will be dealing with Loaders and more Stalkers for you to kill.
You need to get through the door at the Western end of this area. To do that, you need to kill the Stalkers and the Loaders of the area. After the initial run of basic Loaders: EXP, GUN and Bul Loaders and Stalkers, you will encounter a Badass Stalker then a Super Badass Loader. This means, shock and corrosive weapons can carry you through here the easiest. Kill them all and you can get through the doors into the next area: Specimen Maintenance. Just follow the path forward and to the right to find where they are keep Bloodwing. Go inside the enclosure and to the far end of it.
On the ground you will find a Feather sitting on the ground. Grab it to move things forward.