Why is relying solely on historical averages for timing a Blue Wildebeest river crossing in the Mara potentially misleading for visitors?

Because rainfall variability dictates grass quality, which in turn causes the northward push timing to be fluid and delayed by dry years.

The migratory timing is inherently fluid because it is governed by rainfall patterns that determine the quality and availability of grass. A particularly dry year in the Serengeti means the grass remains insufficient for sustenance, forcing the herds to linger longer in the southern plains. This delay means the northward push toward the Maasai Mara might be postponed past the usual dates. Therefore, a visitor aiming for a specific historical month must check contemporary reports, as the actual grass condition acts as the true locational guide rather than merely the calendar month.