To further expound on Edge's comments, which are spot-on regarding purchasing a tripod with wind stability in mind. I have found the center column to add a great deal of shake when extended (look at Larry Lade's iconic facebook photo of himself at his scope with center column extended and you can see what I mean...sorry LL : )... I have tested this in the wind up at Smithville Lake with center column extended and the shake is unbearable. When I lower the center column and extend the legs of my tripod to it's full height, the shake virtually disappears. After discovering this, I have removed my center column completely to cut down on weight (a few "Unit 4 Death Marches" prompted this action). Fortunately, I unwittingly purchased a tripod tall enough with legs fully extended to negate the need for a center column adding additional height; a shorter tripod would require a center column.
Also, the detail-oriented birder might want to check the compatability of a tripod with legs fully retracted. When it is really windy, I lower my tripod all the way down and sit cross-legged on the ground while scoping, often using my car or an inverted picnic table, etc. as a windbreak; hanging a 5-10 lb. dumbell from the tripod head helps, also.
Quick-release plates are an essential item, especially if alternating between tripod and window-mount. I use a standard Manfrotto quick-release plate, PLUS a Manfrotto model 200USS stabilizer on top of the quick-release plate. The stabilizer virtually eliminates any shake from the area where scope connects to tripod head. Best $30 bucks I've ever spent.