AmericanBison_Inbreeding_Derr_Jim_CollegeStationTX_17February2023_Reel4142.mp3

Jim Derr [00:00:00] In 1997, when Texas Parks and Wildlife took over the bison herd from the JA Ranch, they brought those animals to Caprock Canyon State Park.

Jim Derr [00:00:12] They had people to take care of those bison. They had people to feed them. They kept them in a fairly small 100 or so acre enclosure. And they had excellent nutrition. They had excellent veterinary care. They had a really nice pasture to live in. It was a healthy place for them.

Jim Derr [00:00:31] And they started that population in 1997. And the first year, they didn't have any calves or very, very few calves that made it that were born and survived. And the implication was then, "Well, maybe it's just because we moved them and they're in a different environment. Next year things will be better."

Jim Derr [00:00:52] But then the next year, in 1999, they weren't any better. Again, very, very few, if any, calves were born alive, and the ones that did died soon.

Jim Derr [00:01:04] Something was going on.

Jim Derr [00:01:07] And then in 2000, the same thing.

Jim Derr [00:01:09] And then in 2001, pretty much the same thing.

Jim Derr [00:01:13] And the problem, the problem was, when we went and looked at the genetics of these animals, these animals, because they had been kept on the JA for over 100 years, males had been removed by various means, sometimes hunting, sometimes by castrating the bull calves. But the males had been removed so that not very many males were doing the breeding.

Jim Derr [00:01:38] And the population was really small. It may have been 100 at some times, but it may have been 25 at some times. So the population fluctuated quite a bit, but it was always really small.

Jim Derr [00:01:50] And with a few number of males producing offspring per generation, what happened was they started to suffer from inbreeding. And as a matter of fact, by the time Texas Parks and Wildlife took over this herd, this herd was in full-blown inbreeding depression.

Jim Derr [00:02:09] And when we went and we fertility tested all of the bulls at Caprock Canyon State Park, I think in 2001, none of the bulls passed the fertility test. So the problem was that we're not producing sperm cells that would meet the requirements for fertility in a domestic animal.

Jim Derr [00:02:33] So we knew there was a problem.

Jim Derr [00:02:35] Then as a geneticist, I started looking at this herd and saying, "Well, at least from 1997 to 2001 or 2002, they've only recruited a handful of calves into this herd." And so a graduate student and I did a quick calculation of the average age of the bison in this herd. And most of the time, if you're replacing the animals that die with newborns in a population, the average age of a population will remain fairly constant. What we saw at this herd in the early 2000s was this herd was increasing in age, the average age of this herd.

Jim Derr [00:03:19] And it was going to reach a point, if it kept going the way it was going, and it looked like without intervention, it would, this herd would fall into what biologists call an, "extinction vortex". And that's where you don't produce enough offspring to replace the animals that are dying. And the average age of the herd increases every year to the point that the majority of the animals in the herd are too old to reproduce. And that is what we call an extinction vortex.

Jim Derr [00:03:55] And that means that population, without some kind of drastic intervention, that population is going to become extinct.

Jim Derr [00:04:04] So we realized in about 2002, 2003, that was where this population was.

Jim Derr [00:04:13] We all knew it was a very valuable population because it was the last remnant heard from Texas of bison. We also realized, with some modeling and with some research that we had done, that this herd had a very high probability of going extinct by about 2040.

Jim Derr [00:04:35] So, we had to do something.

Jim Derr [00:04:38] So, the idea was, looking back at the history, in 1902, Charles Goodnight had sold three bulls to help reestablish Yellowstone National Park. And so I thought, "Well, man, wouldn't it be great if in 2002, 100 years later, we bring three bulls from Yellowstone National Park to try to do something about this inbreeding problem here at Caprock Canyon State Park. Man, that would be great." That would be a wonderful hundred-year kind of story where that herd was used to rescue bison at Yellowstone National Park. And then the bison in Yellowstone, 100 years later, could rescue Charles Goodnight's old herd.

Jim Derr [00:05:21] The problem was that the bison in Yellowstone National Park have that bacterial disease brucella, and there simply was no way we could take bison out of Yellowstone and bring them to this Texas herd because that just simply wasn't going to happen.

Jim Derr [00:05:37] So we searched around for the next best option. And there is a herd in New Mexico. It's owned by Ted Turner. It was a herd that was on the Vermejo Park Ranch. It's called the Castle Rock Herd. And that herd was moved to that ranch sometime in 1930s, 1940s. The majority of those animals did come from Yellowstone National Park. We knew, because we had done some genetic testing in that herd, that was a very genetically healthy herd. It was a Yellowstone lineage herd. And they did not have infectious diseases like brucellosis.

Jim Derr [00:06:18] And so, we approached Mr. Turner. And he agreed to provide three bull calves for Texas Parks and Wildlife to put in this herd at Caprock Canyon State Park.

Jim Derr [00:06:33] So, we got the bulls. They were young bulls. We kept them in quarantine for a year because we were, you know, cautious that we didn't want to, we didn't want to introduce them to the, to this herd too quickly. We wanted to make sure they were healthy and we wanted to make sure that everything worked out right.

Jim Derr [00:06:51] And then in the second year, we just exposed one of the bulls to the cows at Caprock Canyon State Park to see what would happen, as an experiment.

Jim Derr [00:07:02] And that one bull, I believe, produced, I can't remember exactly, I think it was 13 calves that next year.

Jim Derr [00:07:10] That was the most calves that had ever been born in that herd. And this was in 2005. That was the most that had ever been born in that herd in one year since that herd was established in 1997.

Jim Derr [00:07:23] We knew for a fact that this was going to work. And and the fact of the matter is, it did work and it worked very well.

Jim Derr [00:07:34] So, we used one of those other bulls the next year, and he produced 15 or 16 calves that were put in the herd.

Jim Derr [00:07:41] Then a couple of years later, we went back to the Vermejo Park Ranch and got a couple more bulls and brought them and use them as breeders.

Jim Derr [00:07:51] And now when we look at this herd of Caprock Canyon State Park, it started with 37 or so animals. Now that herd has over 300 animals. Genetically, it is much healthier than it was 25 years ago. That herd is completely self-sustaining. We eliminated that extinction vortex. We turned around the problems with inbreeding, and that is a genetically healthy herd, and it still represents the last remaining herd of that great herd that occurred, you know, in the early 1800s that extended all the way down into Texas. It is the last, it is the most southern part, of that bison herds lived in Texas and all through the plains in the 1800s and before that.

Jim Derr [00:08:52] So in my view, it's a success story. We took a herd that was going to become extinct. We knew that it was valuable. And we figured out a way to use genetic technology to pick a herd that was free of diseases and had the right genetics to bring back into that herd. So it worked.

Jim Derr [00:09:14] And you can go there today and you can see these bison today and they're extremely healthy and they're doing very well. And every spring there's a ton of calves in that herd now.