Today Laddie and I worked with a single assistant at a location that contains a 45 degree slope between one field and another. The slope is approximately 150y end to end and about ten yards wide (that is, from the high edge to the low edge), ideal for the drill I wanted to work with Laddie on today.
Laddie ran about a dozen blinds, in each case from a starting point midway down the slope to a black bumper about 80y away, also midway down the slope. We ran in both directions for variety, sometimes using a lining pole to mark the black bumper and sometimes not. The advantage of the lining pole, from a training perspective, was that Laddie ran the entire distance staying at the midpoint of the slope when the pole was visible, whereas he tended to drift uphill when it wasn't there. The disadvantage was that it apparently made the challenge of ignoring the diversion easier.
What diversion? Oh, I haven't mentioned that yet. Except for the first time or two that Laddie ran the blinds, I had our bird-girl throw a white bumper. The early throws were from the bottom of the hill, about a third of the way from the start line to the black bumper, and thrown away from the slope. To increase difficulty, she moved away from the start line and closer to the black bumper to make the throw. Another way to increase difficulty was for her to move toward the middle of the field and throw toward the slope. Most difficult was for her to stand at either the top of the slope or the bottom and throw over the line Laddie would be running, a blind's relationship to a mark called "under the arc".
The setup I'm describing is similar to an invaluable drill Alice Woodyard sent me to use with Lumi and Laddie when they were first training to run blinds, but that was on flat ground, the lining pole was always present, the bumpers at the pole were white, and the diversion bird (a real bird in those days) was thrown and retrieved before the dog was sent to pick up a bumper. This prepared the dogs for every relationship between a thrower's position and the line to a blind run in that gun station's proximity.
Today's drill would not have been suitable for Lumi and Laddie in those days, because in today's drill, I sent Laddie to pick up the black bumper on the hillside first, while the white bumper the bird-girl had just thrown lay there on the ground as a powerful diversion. After Laddie returned with the black bumper, I released him to pick up the white bumper next, which he was always excited to do.
A mark that's thrown but left alone while the dog then runs a blind is called a "poison bird". I haven't seen many of them in competition, but I've heard that they are sometimes used in master hunt tests and all-age field trial stakes. The most difficult would be an under-the-arc poison bird using a flyer, and I've heard that even that variation sometimes occurs.
We weren't working with birds today, much less flyers, but Laddie did get practice running a good number of poison bird placements, including today's most difficult variation to end the day - the poison bird thrown far from the start line from the bottom of the slope to the top, the blind run under the arc, and no lining pole at the black bumper.
At the same time, Laddie also got a good bit of practice running along a slope at midpoint between top and bottom, a valuable skill in its own right and, I thought, a helpful complement to the poison bird setups.