October’s goulash

As these monthly goulashes go, this one is sparse. Only three images: two birds and a mammal.

Here a Bald Eagle dives off of its perch on a tree. This raises the question of why it dives, rather than just flies off. Flight is a unusual means of travel. Unlike ground or water travel, where the faster one moves, the more energy it takes, flight doesn’t work that way. Slow flight takes a great deal of energy to just keep airborne; fast flight takes a great deal of energy to overcome air drag. Between these, there is an optimal minimum-energy flight velocity. For the eagle this is about 12 metre/second (~43 km/hr). So an eagle needs to dive off a perch to use a gravity assist to pick up enough speed for optimal flight. Of course, that is also true of other birds.

Obtaining a shot of a bull elk deep in the forest is not easy. This is one was taken by Doug Thorburn, who shared it with me.

In the dying days of October, people began reporting the appearance of Trumpeter Swans from various places around the Lake. Here is one I saw.