Bird is 70 feet in tree.. picture is level .. wtf.. and how.. lol

It depends greatly on the photographer and the bird as well as the shooting environment and the gear to hand.

1) Remember that when you look at a pros portfolio online or in a book you are seeing a tiny (and I mean tiny) selection of their shots - there will be countless thousands which have been dropped for big and small reasons; they will have good days and bad days. So firstly never think that they will get the shot they want in every possible situation - they have limits too they just don't tend to show them as much

2) range and quality at range - if you have a high quality long range lens you can shoot from further back which means more chances for using a higher hide, a hill, a tree and also the effect of shooting from further off which will reduce the angle at which the photographer has to shoot ( thus giving a more in line with the bird image)

3) Hides, lures, feeding stations and squirrels - feeding stations and other luring methods are very often used to bring an animal into a semi controled area. That means you can bring the bird lower and get those lower angle shots that you would not have been able to do before. These can be simple of complex setups and rely on understanding the species you are attempting to photograph (or at least the general aspects of the species you would possibly like to attract).

4) Hides - often in combination with lures or knowing feeding/marking/traveling locations of the animal in question - can take all shapes and forms and are a good way to get the shots. And of course if you need an underwater shot of a crocodile one way is to build your hide under the water - or up a tree. Of course the more elabourate the hide the more risk and cost will be involved (As well as the likley amount of gear needed to carry the setup)

5) Trips and traps - often a photographer in wildlife wants to get a shot of a very elusive animal. This might not be possible even with a lot of field skills and resources since the inclusion of the human in the shooting area can risk scaring the subject away from the shooting area - and in some cases the life of the photographer might also be put at risk (which in turn can also put the animals life in danger as well - mankillers/attackers are very much at risk of being hunted down - the resulting hunt often leading to the chances of their being additional animals shot or injured until the risk animal is removed