Paraglider Pilots about Soaring and Thermalling Birds

Paraglider pilots often meet birds during flight. Most of us would probably agree that the best encounters are found when sharing a thermal with a gaggle of pelicans or going on transition with a vulture. Birds are great company and they offer important clues about thermals, dynamic lift, turbulence and sink. Some time ago I started a topic on paraglidingforum.com so pilots could share their insights and experience with birds. Reading all the great input gave me another idea: organize the bits and pieces of information into a more structured story for more efficient reading. The resulting article here is therefore in no way a complete or exhaustive study of this subject but a collection of observations of paraglider pilots about how birds thermal and what we can learn from them.

Kurt N, a contributor to the discussion raised an important issue with paraglider pilots’ knowledge of birds: most pilots don’t identify birds on the species level, but rather recognize them as “types” of birds: vultures, eagles, falcons. This approach can be misleading because different species in a genus or family can have different characteristic behaviour, like the black vulture and the turkey vulture found in the Americas. Despite this, I have kept this generalistic approach of pilots unskilled in ornithology, because it suffices in most cases and I only added species-level identification where needed and available.

Turkey vulture (left) and black vulture (right). Source: http://trekohio.com

Vultures

Vultures are great ones, and super friendly. They are also super inquisitive and will climb a thermal with you just out of curiosity. This was confirmed to me when I was searching for a thermal with zero birds in sight, and a few minutes after finding it I see myself surrounded by 300+ vultures that followed me on the next transition when I left the thermal. On the other hand they don’t pay much attention to air traffic, so be prepared to shout at them every now and them to wake them up. (neliob)

Had a friend collide with a vulture in Nepal. The vulture grabbed his harness, and he beat the vulture out of instinct to convince it to let go. They don’t seem to care about air traffic at all. (balamber)

When I used to fly the Himalayas regularly, I never saw a vulture join the thermal the wrong way. And they would really let you know about it if you tried to change the direction of the thermal when they were already established in it. I think they just work on the basis that everyone knows (and obeys) air law – so they don’t need to worry about other traffic. (HimalayAir)

In practice, I tend to follow vultures more once I’m in a thermal than I do with hawks (hawks have led me astray many a time, vultures almost never). Nevertheless, they are both excellent at marking a thermal in the first place! (DTM)

Once in a thermal I was following a vulture and he suddenly folded up his wings and rolled away, out of the thermal. I had just enough time to think “that was weird” and then I took a big frontal collapse. Whatever it was had been big enough to tip him out upside down too. (Grecian)

Vultures are the best helpers, not only because of the thermals but mainly because of the transition lines. If you fly alone you are not on the best line. When on the best line you are always in company. In Brazil, pilots share thermals with the urubú (black vulture), but pilots of course are not able to climb as well as they do. The other vulture here is the red-headed urubu (turkey vulture). The turkey vulture acts more like a butterfly than like a bird. It climbs in rotors and turbulence and flies close to the terrain. To go after it is a big error. It mainly flies on the lee side. (Vidimart)

In the Americas two very common vultures have very different flight characteristics: the black vulture tends to fly in groups, be attracted to other thermalling entities and to fly directly toward them, core lift, top out thermals etc. They are a perfect bird companion for the XC pilot. The turkey vulture, however, tends to fly low in search of food, to work micro-lift seams and leeside eddies, and to constantly leave good lift. Both are vultures, but following one type is highly productive and following the other is often a fast way to sink out. (Kurt N)

In defense of turkey vultures: the birds here in British Columbia thermal quite well, much better than bald eagles. Our vultures often out-thermal paragliders, like to push very deep into terrain and then climbing in super light lift. It’s easier to keep up with bald eagles and quite fun especially in the fall and early spring when they seem to fly just for fun. Especially the juveniles are very curious and approach rather close. One followed me a few meters behind for about 5 minutes a couple of weeks ago. We don’t have black vultures here but I made their acquaintance in Colombia and they were much easier to thermal with than our turkey vultures. (Winglt)

Golden eagle soaring a thermal and being harassed by a raven.

Eagles, hawks and falcons

I have found hawks to be less reliable at marking thermals for long periods of time as compared to vultures. I think this is due to the fact that hawks tend to leave thermals more often on purpose (for whatever reason they have). They simply seem to be less concerned with staying in lift than vultures (I think vultures hate flapping their wings way more than hawks do). (DTM)

Hawks and falcons thermal in search of food so the don’t go very high usually. (tsahi)

Eagles/falcons – they thermal really well and always find the strongest cores. You can count on them to find you a thermal if you are high and far from their home territory. In this case they are “cooperative” and fly with you like equals. If you are on their territory – they will trick you and get you into sink. This happened to me many times. Of course it’s a really bad idea to get close during their nesting period (in Bulgaria it’s April – May)! They always warn and if you don’t fly away – they start to attack. (DVD)

In Romania near the Danube (Dobrogea) region we also had a spotted eagle attack and tear paragliders if pilots flew close to her nest in spring. It climbed above the glider, dived down, grabbed the leading edge with one leg and tore it with the other. Scary! (balamber)

In the UK I joined a buzzard in a thermal – he took a dislike to me and dived at me two or three times with wings folded and claws extended, screaming as he came, and pulling away at the last moment. Luckily the thermal was big and strong and we ended up taking different cores to cloudbase… (Al Wilson)

Eagles and hawks use resident thermals and do not have real interest in moving around, they just mark their territory and your wing with their shit. (Vidimart)

Eagles and kites core like gods, and can core on a dime. When migrating, on some days they are very consistent in keeping the core all the way up and on some days they seem to have their own “speed to fly rules” and seem to see the next thermal and jump forward after a short climb. (tsahi)

Wedgetail eagles seem to just… read it all and do whatever they want. I’ve seen them fly big, lazy flat and incredibly wide circles around me – that was an education in terms of how big a thermal can be – but I’ve also seen them coring tight and fast, banked up.

They also seem to enjoy ‘boom and zoom’ activities – they’ll dive with wings folded, and then zoom back up, with very little height loss, often doing it with a partner bird. I’m sure it’s a territorial or mating display, (or some other prosaic rational reason) but it does look as though they are just plain enjoying some aerobatics. (jpdv)

Red-tailed hawk harassing bald eagle.

Swallows

Swallows, from what I understand, like to fly in thermals less because of the lift itself and more because the rising air tends to bring flying insects with it that the swallows feed on. This is just hearsay though, so I’m not sure that it’s accurate (they sure do seem to dart around a lot in the thermals though, which is consistent with feeding behavior). (DTM)

Swallows – they don’t thermal in our sense of the word, but fly randomly in the rising air. If you see anywhere more than one swallow – you can be sure – there is rising air. They are really helpful in late afternoons when the clouds are gone and the thermals are weak. (DVD)

Hey Daniel, I don’t think that “you can be sure – there is rising air” if you see swallows. They sometimes go to catch insects in massive sink too. (bujak)

On a good day on the hill I’ve wondered about the lack of swallows/swifts using the thermals… until I’ve got to base and suddenly there they were all! I guess there are so many insects sucked up that they don’t need to stay low. (tim8061)

On my local soaring site the true wind direction is sometimes hard to tell from takeoff. I use the swallows there as wind dummies. When there are none, or they are less than 15 meters above launch the wind isn’t strong enough for paragliding. The further out from the hill they push, the better. Also when they turn and head into wind it’s an easy way of telling the true wind direction. (skippieralph)

Swallows feed in thermals. They are great indicators at base 2000 meters above ground where vultures have no interest to stay. (Vidimart)

The Alpine Swift is a great thermal marker in Central Europe – big enough to see at a distance and small enough that it doesn’t mind sharing. (Mads S)

Storks lazy soaring.

Storks

The storks I found were very bad thermal markers. I only ever found them flying very low and on super weak thermals. (neliob)

They are lazy and they are really good in catching the thermals (or bubbles to be more precise) as low as possible. I have seen storks to catch a thermal from less than 10 m above the ground! If you are low and there are storks around – you have chances. In the thermal they circle in random directions. Often they look sideways and realize that you will collide in the last moment. Yelling/whistling doesn’t seem to improve their awareness. If you are high – usually they will not help you – they only turn a few circles in lift that we cannot use and continue on glide. (DVD)

We see a lot of storks here in Central Spain too and, in my experience, 99% of the time storks circle in sink when they are lining up above their nests, usually above the villages. Fell for that one a few times when I first moved here. (Rob B)

 Ravens playing in dynamic lift in strong wind.

Ravens, rooks, crows

Ravens thermal almost the same way as eagles but with the difference they are not territorial. The best help from birds I have ever received is from ravens. Another plus is the fact they are easy to spot from distance. (DVD)

Ravens are quite good and very playful. Closest I have seen to avian acro, thermal up, dive bomb the height away, throw in some inversions, rinse and repeat. Just for the hell of it, it seems, and they do synchro as well. (mm)

Here in England crows (or possibly rooks) thermal a lot, but they often confuse us by flapping as they go up in the thermals. (AndrewCraig)

Rooks will thermal up from their rookery when a cycle comes through, seen it loads of times. Sometimes they seem to do it for fun, other times they then glide off to presumably a nice ploughed field somewhere. (tim8061)

BTW I see crows thermal regularly. Here in Berlin, (Tempelhof field) they hang out on a fence that happens to trigger thermals and when a cycle comes through, they go for it and have fun with much noise. They mostly don’t seem to have any goal, they just play and are social, maybe bully the local falcon and mostly land again after the cycle.

One can observe it best in winter; there are not so many thermals and the crows seem to use each and every one. In winter, there is always a bigger release in the afternoon/evening when the sun begins to settle. It’s amazing to see how they climb as a gaggle, with a couple of outliers always searching for better lift outside of the main group. (bujak)

On some areas we have a rule that if there are ravens thermalling it is ok for us to fly. If they are flapping and not climbing consistently you are sure to bomb out. I think that from all birds we are closest to ravens in terms of thermal strength needed for climbing. (flythesky)

Over here (German hills / flatlands) when you see the crows having fun and playing in the moving air, then you can leave the wing in the bag; the wind will be too strong. (Erfurt Bob)

Crows are regular thermallers in the Himalayas during some part of the winter when they go up to the ridge top every evening. I have a flock of 50 or more crows gathering at my flying site here, most of them sitting on the trees while a few keep testing the air for thermals. When these do find a good thermal release the whole lot launch together and up the go. Lots of calling to and fro all the time. Pretty well organised on the whole. Picked up a tip or two about thermal release time from them. (Late winter and early spring while its still cold, thermals are best later in afternoon than i thought on this south west facing site, I was flying about half an hour too early.) (pathak)

Big gaggle of pelicans soaring.

Pelicans

I’ve seen a gaggle of white pelicans join my thermal in formation, take a few wide turns and then glide off, almost without breaking formation. (Josh Cohn)

Oddly enough, I have witnessed a large gaggle of pelicans thermalling (close to 100) and above them was a gaggle of vultures coring tighter and much higher. What I noticed was the vultures were much more efficient about the core. Also, I witnessed the whole gaggle of pelicans switch direction at the same time. That was pretty cool to see and has kept me wondering… (Mike Jobin)

White pelicans (inland, fresh water) are amazing thermalling. We see them climbing @ 8.30 am when we wouldn’t even consider launching before 11. (mm)

Pelicans thermal as a gaggle so they thermal better on big thermals and just circle around on small thermals. They have a lot of patience on the weak and small thermals. (tsahi)

Pelicans soaring in dynamic lift.

Cranes

Cranes also fly as a gaggle but they seem to have no patience whatsoever. If the don’t find a big and strong thermal they just start flapping and dig forward. (tsahi)

Cranes and other aquatic birds are really unpleasant to fly with. Vultures never enter the white room, but water birds do. So you may get a crane in your face inside a cloud. (Vidimart)

Seagulls

Seagulls thermal quite well and saved my ass down low many times. They don’t climb very high though, they just dart off to where they need to go as soon as they have enough height. (bujak)

Final note

I encourage people to learn to identify the various species of soaring birds in the areas they fly. It will make your experience of the nature you fly in more enjoyable and for the pilot community in general and it will make observations of soaring birds more useful when shared. (Kurt N)

The highest flying birds: bar-headed geese flying over the Himalayas.

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