Thursday, March 26, 2009

Why did the bison cross the river?

To get to the other side.

Every April and May in Yellowstone National Park bison cows give birth to beautiful red orange calves. Bison calves are quite hardy and able to stand up to nurse within minutes and walk an hour or two after being born. Until they are a couple of months old it is important for baby bison to stay close to their mothers and the rest of the herd. Young calves may become an easy meal for Grizzly bears, black bears, and wolves until they are strong and fast enough to get away.

American bison are always on the move and Yellowstone has many rivers coursing through its more than two million acres. When a herd of bison come to a river they need to cross, young calves stay right at their mother's side and across they go..

Three bison cows and two new calves walk across a shallow part of the Madison River.

You can see here the water is now much deeper and the first cow and calf must swim.

There were a lot of grunts and other vocalizations going on between the cows and calves during the crossing.

This cow is using her nose to nudge her tired calf up onto the bank after swimming across the river.

Here another cow and calf pull themselves out of the water and onto the riverbank.

This cow is soaking wet as the calf uses its front hooves to climb up on the bank.

After the successful crossing the cow and calf walk off to rejoin their herd.

All of the calves safely made it across the river. Though one calf did get caught in the current and washed downstream about 100 yards from the rest of the herd, That calf plaintively called for its mother once it made it to shore, then ran and rejoined the herd. The cows and calves were grunting and vocalizing a lot during the crossing and I can only imagine the cows were encouraging their young to keep going until they reached shore.

I always feel lucky when I see large mammals in the water and being able to watch a herd of bison with new calves swim across the Madison River was big fun.

1 comment:

Brad said...

Thank you for this post.
Bison are my favorite animal and I love seeing photos of them.
Great photos too.