Getting Airborne: Why Loons Don’t Visit Your Birdbath
This morning the YouTube chatters were discussing humidity and air pressure and how they might affect a loon’s take-off length. It’s true that humidity affects air pressure and air pressure is one factor in determining the speed needed for a loon to get airborne, but there are other factors with greater influence. And while we’re waiting for the first pip sighting on the nest, this could be a good time to talk about the distance a loon needs to take off from the water.
First, the basics. Loons are designed to dive and swim underwater. Everything else is secondary. Thus, they are denser than other birds so they don’t bob back up to the surface as soon as they dive. Also, their wing surface area to weight ratio is much less than most birds, which makes the loon more streamlined and faster swimmers when the wings are folded. They’re heavy birds with small wings; they need to be going quite fast to get airborne. So, instead of acting like a VTOL (vertical take off and landing) aircraft, they’re more like a B-52: a long distance running and building up speed on the surface and then a very flat climb attitude.
If you peruse the web you’ll find a wide range of estimated distances a loon needs to take off. My recent search produced results ranging from “30 yards” to “a quarter mile”. Both are preposterous. The 30 yards was probably a typo; they left out a zero from a maximum estimate. The quarter mile (which would be 1320 feet) was sloppy research. It’s true that a loon lake will usually be at least a quarter mile long (there are exceptions), but that’s not the take off distance. Once a loon gets airborne it’s literally not out of the woods yet. It still has to clear the trees and any other obstacles on the shore. That’s where the quarter mile distance comes into play.
Based on the literature and personal observation, a loon take off run will usually be anywhere between 200 and 600 feet. Following are three factors that most heavily weigh on the distance.
Wind Speed. Just like airplane pilots, loons prefer to take off into the wind. If a loon has a ten to fifteen mph headwind, they’re starting off at a big advantage. Remember: it’s air speed that counts; not ground speed.
Fitness. Not all loons are equal. Some are stronger, some are weaker. And disease and injury can come into play.
Determination (motivation). How fast does the loon want to get off the lake? If it’s just taking a joy ride to check out another area there’s no real need to put the pedal to the metal. On the other hand, if it’s being chased by a larger, angry loon, you can bet the take off distance will be much shorter than normal. This factor first became apparent to me while doing loon rescue work. A not uncommon rescue LPC does is retrieving loons that land on tiny ponds. They seem to love golf course water traps (so aptly named) and large puddles in gravel pits. Don’t ask me why. What we’ve found is that if there is a straight shot of at least 200 feet, it’s worth waiting for the loon to make a move. Sooner or later (2 or 3 days) it gets desperate enough to give it the old college try and they usually make it on their own. It saves LPC a lot of time and effort and it spares the loon the psychological trauma of being chased by a couple of sweaty field biologists. It’s a WIN-WIN.
