# Is there a name for the fast decline + pull to climb pattern?

I'm a hobby photographer and I've noticed some patterns in the bird flights, so I tried to poke a bit into the aviation terminology for it. Phalacrocorax carbo does this movement similar to the attacker's 3 in the Displacement roll when declining just slightly above the water and then it pulls itself up slightly by doing this roll first, then slight pitch movement to continue the declining curve but to also gain some altitude while braking the movement and afterwards switches to gliding above the water.

Sometimes these movements are seen in action movies, so I think there might be an aviation term for it although perhaps only for the full "fighter maneuvers". Any ideas?

Example with the bird's flight trajectory:

Edit: I think the wind is coming under the bird's chest or from the side and I don't think I've ever seen a bird utilizing the same pattern in windless or in very weak wind environment (in those cases it was mainly gliding without turns or climbing).

• Welcome Peter, I'm not sure I understand the whole pattern you're describing (because you mix the pattern description and the bird actions to follow this pattern). So far my best guess is you're describing a descending turn close to the water followed by a turn at water level, constant altitude, like in the part 3 you show on the picture. Also is that similar to this (3rd picture)? or that.
– mins
Aug 28, 2021 at 13:29
• @mins thanks. Yes, it's similar to the 3->4 stage of this link. So far the descending turn + turn + constant altitude match the pattern. I guess there isn't a fancy naming for it as for "Displacement roll" or likes, right? Aug 28, 2021 at 13:34
• Do you think it is a dynamic soaring technique, i.e. does it appear to be extracting energy from the wind gradient? I.e. are climbs consistently performed with a headwind component and descents with a tailwind component? Which direction is the wind from, in your description? Or does it do the same thing even when there is no wind? I think birds make brief use of dynamic soaring techniques to extract energy from the wind gradient much more often than is commonly believed, even if it does not result in full-blown long-term-sustained non-flapping flight as per the albatross. Aug 28, 2021 at 14:18
• PS any climb that is performed or enhanced by exchanging airspeed for altitude is called a "zoom climb", but that's only one small part of the full pattern you are describing-- Aug 28, 2021 at 14:23
• It would be helpful if you would edit the question to address which way the wind is coming from and whether or not you've seen the maneuver performed in calm conditions also--- Aug 28, 2021 at 14:34

Totally didn't get the comparison with jet fighters until reading your reference for Phalacrocorax Carbo, aka great cormorant. The bottom plane is the fish it's pursuing, which makes the entire manuver worth discussing.

Cormorants hunt by diving on slower, more maneuverable prey, which have the advantage of the denser medium (water) to turn and force the bird to overshoot.

As with the upper jet fighter, the bird can increase its maneuverability by slowing down. This is done by trading speed for height (kinetic energy for potential energy). The part you are interested in is the result of the top plane rolling sideways to fall vertically, or "slip". A cormorant, or an aircraft, does this to start a dive without negatively loading its wings, which are usually much more tolerant of positive loads.

If the cormorant decides not to dive into the water, it will abort by rolling out and increasing its angle of attack to glide away.

One last trick the bird may use is to fly away low over the water to take advantage of "ground effect" (less drag for the same amount of lift) while it continues its search for dinner.

As far as the observation that they do this less on calm days, one might surmise that the ripples on the water surface will make it harder to see what is below, making for more "false positives" on its target acquisition system (eyes-brain).

• This + an analogy "not to crash into water" made me think that there has to be some tern for that (because similar or the same thing is often present in the action movies where a plane isn't supposed to crash into an urban area), of which dynamic soaring makes the most sense (for the bird) and also encapsulates the patterns you describe, though probably not the weather. Aug 28, 2021 at 15:04
• @PeterBadida rolling out of a slip is so commonly used (for aircraft approaching a runway) I'm not sure it has a special name, but great observation (and photo) anyways. Aug 28, 2021 at 16:32