For the first time in a number of years, the great wildebeest migration seems to be “on track.” This means when I return to Africa in a few weeks that I should be able to show my clients a dramatic river crossing in The Mara.
This year the weather was fairly “normal” as defined by the mean of the last twenty years. Parts of Tanzania suffered a mini-drought, and the lands of the wilde were a bit dryer than “normal” but all within the margin of “normal.” But does “normal” mean anything, any more?
Until this year for the last ten, the migration has not been “normal.” It’s been fractured and misdirected by radically changed weather. Ironically that means this year’s “normal” is “abnormal!”
And it’s not just wildebeest that are being effected.
Animal, bird and even butterfly migrations are mostly driven by weather. We know, now, that the length of daylight, the earth’s magnetism and even the patchwork of the starry nights also plays a role. But the main driver is weather.
Everything starts with temperature and rain. The correct combinations bring forth the correct bugs and leaves and berries, and those in turn attract the birds and butterflies.
Big animal migrations like the wildebeest of East Africa and the caribou of North America depend upon grass and lichen, and these too emerge with the right weather, when it rains.
So you can imagine how the world’s migrations are being torn asunder when it doesn’t rain when it should rain. It gets even more complicated if it rains just as much every year, but not at the right time.
Wildebeest calve once annually. Normal gestation is 8 months but like many antelope they can delay actual birth for up to another month if conditions aren’t right. So while late February is the normal time, births can occur through March as well.
This is in the middle of northern Tanzania’s rainy season. It’s when the great prairies of the Serengeti move into full bloom. The grasses on the prairies are much more nutritious than the grasses in the highlands or riverine areas further north. Those grasses will sustain the herds, but mom needs the southern plains grasses to produce the rich milk that gets her baby going.
That’s been massively disrupted in the last ten years. Remarkably we’ve seen the rut, or mating sometimes delayed as well, so that births have actually been reported in May and even early June, all this not because the rains have been shifting, but because they’ve been heavier! But at the wrong times!
The weather is extraordinarily complex on the equator and the convergence of jetstreams that starts and stops the rainy season is wildly off balance. If the rains don’t start on time, it’s almost certain to result in a very quick drought.
No rain, no grass. Babies born without the right nutritious grasses die, but the herds have to keep moving looking for grass of any kind wherever the rain falls.
Then if the rains start up heavier and last longer, the track of the wildebeest gets thrown to smithereens. This causes fractured herds, misdirectional migrations and basically a lot of sick animals.
So you agree this is serious? So we want to know how many animals have been in the migration and are now, right? So here’s the data for the Porcupine Caribou herd.
There’s no data for the wildebeest, only anecdotal repeats. Several years ago the Frankfurt Zoological Society announced it was carrying out a census, but then never reported data.
I’m presuming the herds are decreasing. This anecdotal from my own experience, what I’ve observed. But it’s hardly scientific, and it’s a real travesty that organizations working in the Serengeti, much less the government, can’t get this simple action done.
Perhaps like me they know that climate change is serious, that many animal populations are suffering because of it, and with the limited resources that exist, it’s just not worth spending money to prove the obvious.
Regardless, this year is “on track.” Stay tuned. I hope to be in the midst of the migration in just a few weeks.