There are places on earth that just have the perfect combination of geographical features and habitat that make them exponentially more birdy than other places and we appropriately call them "Hotspots". Many of them, like Magee Marsh, OH, High Island, TX, and Fort Jefferson on the Dry Tortugas are legendary hotspots during migration.
A birder's local patch may not have the volume and intensity of those internationally known hotspots, but over time we come to know our birding haunts intimately and appreciate the subtleties of bird patterns and movement within them. Within my own lunch-hour birding patch (and within all my former patches) I have come to discover that there are certain locations that are much more consistently birdy than others...micro-hotspots if you will. Even though the terrain and habitat appear to be equal, some spots simply have more birds than others. Recently, I've been pondering "Why?"
My conclusion is that there naturally exist "bird funnels" - places where birds coming from wide and far are narrowed into a concentrated smaller area for we birders to enjoy. A bird funnel, especially on the micro level may be different than a known fly-way or even than an island of habitat in which birds abound. These bird funnels may occur for a variety of reasons and the theory I think applies to both the mega-world-hotspots as well as the micro-hotspots within our local patches.
Allow me to use my lunch-hour birding patch as an example. Below are satellite images of both the north and south portions of my patch. I have indicated the consistently birdiest sections in orange. The yellow lines show the perceived funneling that I am talking about. At the tip of each funnel is where I see the most birds on a regular basis, no matter the season.