As Melissa says you have to leave enough room for the wings of the bird--Here I was using a fixed 500mm lens which did not allow me enough room in the photo to have been feet and tips of wings.  I realize I needed a shorter lens when photographing birds from my car along the road.  

I still need to find a location with people-friendly birds, with the sun and wind at my back, but here are a few attempts at birds in flight. The Osprey was at Belle Haven Marina, taking off from a nesting platform, and diving for a fish in the Potomac. The Least Tern was at South Cape May Meadows. 

Definitely the hardest aspect of bird photography. Lots of practise ahead for me! Melissa's tips have been really helpful and I have been encouraged to keep trying. Here are some of my successful shots: two silver gulls (great to practise on! ) and a white ibis.

Practice, Practice, and practice - Melissa is right.  I wanted to capture one or more Black Skimmers flying - but more specifically while skimming for fish.  I went 4 evenings to the same location, selecting different vantage points for observing.  The best time was between 7 and 8 PM as the sun was going down.  The light changed a lot during the one hour I was there, and in the end it was quite dark.

The first two nights I used my Canon 7D Mark 11 with 100-300 mm lens and 1.4 extender.  Second 2 night I used my Sony RX10 Mark IV zooming its lens between about 300-600 mm depending upon where the bird was in its flight.  This is very challenging - as multiple birds fly very quickly and my goal was to catch one on a smooth water surface and showing clear reflection of bird.  I used manual mode all the time which made things more challenging for me as many exposures turned out to be off and I found myself using exposure compensation quite a bit.  My Sony does not permit ISO auto in burst mode, so all my 3 values were pre-selected.

This is one of my most pleasing shots as it also shows the trial left in the water by the skim.  My next goal would be to be more right on with exposures.  I was shooing RAW and used the digital editing software provided by the camera makers.  This was my first experience using Imaging Edge from Sony.  (I do not have Lightroom).

I have more experience with the Canon (having shot skimmers before with it) than the Sony.  Its a challenge, and I'll keep trying.  I find Black Skimmers a very interesting species and learned that they do not rely on their eyes for finding prey, in fact their eyes are slit vertically.

I was drawn to the seagulls sitting in a row on this sign and tried to capture this one trying to squeeze in. It was a fun photo because of their positioning and the third one from the right seems to be telling the incoming seagull that there really is n't any more room. The other two photos I too this morning while driving some back roads to get home. I initially stopped to take some photos of the hawk but a red-winged blackbird came in and added a bit more drama.

Below is a shot of an osprey after finding its lunch. Flew directly overhead. SS 1:3200, F5.6, Auto ISO telephoto 600mm.

I have found capturing birds in flight to be the most challenging. I am still struggling but here are some shots from this year that I saved,

Capturing birds in flight has been challenging.  I typically a shutter speed of 2000 and f/5.6 and auto ISO.  I also use some custom tracking settings in my Cannon EOS 7D that are supposed to help.  I also use most of the settings Melissa calls out.  All this aside, I’m lucky if I can get one out of 20 photos to be focused and clear.  Here are a few of my recent  shots.

Fred, I recognize your difficulties as I experience the same. I can manage to home in on a bird in flight up to about 500mm but then lose it. Then I zoom out and back in but it's usually too late. I was very pleased to get this shot of some black-tailed godwits yesterday but the vast majority of my shots were blurred. All the birds I was trying to shoot were fast flyers. It was at sunset so the light was fading, which didn't help.

My biggest problem photographing birds in flight are finding them through the viewfinder when zoomed to maximum focal length. I try to find them zoomed out but oftentimes forget/don't have time to zoom out again. I shoot aperture priority and may try practicing with shutter priority. One question - Melissa is choosing the widest aperture she can but I have also read that closing down the aperture is best to keep the whole bird in focus as the depth of field can be quite shallow especially with long focal lengths. Does anyone care to comment? Despite these issues, I have been able to obtain some very nice photos of birds in flight and share three of them. From top to bottom: African Darter, American Bald Eagle, Ring-billed Gull.