1. The eagle will not show up until you’re completely distracted by the fact that there are people in kayaks on the river on an unseasonably warm February afternoon.
2. The gulls will notice the eagle is near long before you do. Watch what the gulls are doing.
3. When you do finally notice the eagle, you will be on the opposite side of the bridge, and there will be too much traffic to cross quickly, and even when you get to the other side you will realize that you still wish you had a longer lens.
4. When the eagle takes flight, the sun will have set and you will have dropped your shutter speed too low to really capture anything in motion.
And you’ll still wish you had a longer lens.