In the last game session, the player characters built their third road, linking the Woodcutter's Camp with the Terrace of Fallen Horses. This is the second road built across a stretch of the Sea of Grass, the other extending from the Old Road southwest to the Pueblo Hills and "Santa Fe". Their method of road construction across the Sea of Grass is to cut parallel paths through the grass and then perform a controlled burn of the grass between the two. This works well enough, but it really only creates temporary roads as the grass will eventually grow back. As long as the players periodically maintain these roads, the roads will provide a proven path, allowing speedier movement and a significantly reduced chance of getting lost.
But the seasons are turning and soon the auroch herds will return.
Far to the south, at greater elevations, the air is growing cold, heralding the return of winter to the Southern Plains. When the first snows start falling, the aurochs will migrate north to their winter grazing lands, the Sea of Grass. In addition to flooding the area with ornery cattle, the aurochs will eat the grasses and churn the ground – pretty much obliterating the player character created roads. On top of that, with the auroch in the area, rebuilding of the roads will be stifled during the winter.
I'm doing some research, trying to determine when I want the migration to happen. The last game session ended the equivalent of August 28th. [I don't want to deal with the issues of a completely original fantasy calendar, especially as the Southern Reaches are south of the equator and any calendar brought to the area would have been developed north of the equator and be inverted.] I think I'm going to go with an October migration. The herds will start movement near the middle of the month, arriving in the Sea of Grass at the end of October/beginning of November. The herds will stay until March and then migrate back south.
The horse herds that currently occupy the Sea of Grass will get pushed west, into the shadow of the Cold Mountains. The auroch herds will also be followed by predator groups. This will cause a change in the encounter tables for most of the area as the aurochs dominate the area for five months. I have until the end of the month to generate the modified encounter tables, which is entirely do-able.
Tangentially, I've been assuming that a week of game time passes between game sessions to push the calendar along. With each expedition lasting between five to nine days, this moves the in-game calendar along roughly twice as fast as the real world calendar. This allows me to add seasonal color text that changes in something less than a glacial pace. As an additional note, the gap between last session and the next one will be longer as several characters took a great deal of strength damage from the symbol of weakness they triggered and they need the time to heal.
Unless they want to play weakened…