Come on! Where are the baby bison?!

Jess and I initially had high hopes for late winter bison calving this year, but we're now not sure what to expect.  As mentioned in previous posts a bison herd can technically have two breeding seasons (based upon what I've read).  A major one in late summer and a minor one in early spring.  Gestation lasts about nine and one half months with calves born in either late winter or spring depending on the date of conception.

The vulgar (from a human perspective) act of urine sampling was a common sight last spring.

Though we'd never actually witnessed the bison engaging in the "act" ("it" doesn't last very long for bison from what I've heard), our hope for late winter calves this year had been inspired by our older bull's behavior last spring.  At that time the bull's mind seemed to have become clouded with a single-minded interest in the females.  Most of his time was spent actively courting and urine sampling and anything that came between him and whichever female he was pursuing at that time was either ignored or aggressively dealt with.  With all this effort on the bull's part we began to suspect that there would be at least a few spring pregnancies.

Is he a dud? It's hard to say.  Perhaps the bison managed to squeeze in a late summer reproductive frenzy during the time we were in Peru last year, but I find that hard to believe. 

 Subsequent events seemed to provide additional evidence that some of the females were impregnated in the spring.  By early summer everything had cooled-down and the bull surprisingly became friendly towards me.  This friendly demeanor continued through the summer and fall with no evidence of any sexual activity among any of the bison.  At the time Jess and I had assumed that this lack of activity in late summer was due to the fact that they had all gotten pregnant in the spring, but, with no baby bison appearing this winter, We're not sure what to think. 

As of last week I was beginning to wonder if our bull was a dud and had given up reproduction altogether after an unsuccessful spring, but then something happened that put an end to this theory.  I was about to start the long road trip home to northern Virginia when, while driving my car through the pasture, the bull trotted out in front of the car and bluff charged.  This consisted of a short rush in the direction of the vehicle with his tail up and horns pointed in my direction.  About ten feet from the vehicle he stopped his charge and stood pawing at the ground with one of his front hooves.  I got the message, stopped the vehicle, and waited to see what he would do.  After a few minutes I got out my camera and decided to try driving slowly forward.  What happened then can be seen below.

It wasn't nearly as impressive as his initial charge, but I got the point and stopped the car again.  At that point the reason for this big show became clear to me when I noticed that all the females had stopped grazing and were watching us closely from about 50 meters away.  I then slowly backed the car up about 30 meters and put it in park.  All of the females then walked to the bull, surrounded him, and I was permitted to drive by with my car.  I can't say for sure how the females were responding to the incident, but I suspect they found his actions impressive.