To be honest I haven't see that any try to explain how the marking under the wings are bent and curved to follow the under surface contour. Here it is one very simple method in Photoshop.
Go to Filter and choose Liquify. It will take some time until in new window open. Liquify is the filter which enable you to free distort your object or part of it. So the same tool you could see in the left top corner and icon look like finger press into something. This tool is chosen by default. Now see the parameters on the Tool Options on the right side. First set brush size in regard to the size of object you want to shape. I keep brush density at 50 as well it is good. Brush pressure is 100 and Mode is chosen from drop down menu as Smooth.
When you set all of this all you have to do is to put brush over the object, left click and hold and pull into the desired direction. It works