Bison affected by climate change, may impact cattle similarly

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MANHATTAN -- As temperatures go up, bison get smaller.

Joseph Craine, research assistant professor in the Division of Biology at Kansas State University, examined how climate change during the next 50 years will affect grazing animals such as bison and cattle in the Great Plains. The study, "Long-term climate sensitivity of grazer performance: a cross-site study," was recently published in the peer-reviewed scientific journal PLOS ONE.

"Bison are one of our most important conservation animals and hold a unique role in grasslands in North America," Craine said. "In addition to their cultural and ecological significance, they're economically important both from a livestock perspective and from a tourism perspective. There are about half a million bison in the world."

Craine analyzed a data set of 290,000 weights, ages and sexes collected from 22 bison herds throughout the U.S. The information came from herds owned by the university's Konza Prairie Biological Station; Oklahoma's Nature Conservancy; Turner Enterprises; and other federal, state, nonprofit and commercial entities. The organizations kept annual records of each animal in the herd and matched the data with the climates of the sites.

Based on differences in sizes of bison across herds, Craine found that during the next 50 years, future generations of bison will be smaller in size and weigh less. Climate is likely to reduce the nutritional quality of grasses, causing the animals to grow more slowly.

"We know that temperatures are going to go up," Craine said. "We also know that warmer grasslands have grasses with less protein, and we now know that warmer grasslands have smaller grazers. It all lines up to suggest that climate change will cause grasses to have less protein and cause grazers to gain less weight in the future."

Craine said the results of climate change in coming decades can already be seen by comparing bison in cooler, wetter regions with those in warmer, drier regions. For example, the average 7-year-old male bison in South Dakota weighed 1,900 pounds, while an average 7-year-old male bison in Oklahoma -- a warmer region -- weighed 1,300 pounds. The cause: grasses in the southern Great Plains have less protein than grasses in the northern Great Plains because of the warmer climate.

"The difference in temperature between those two states is around 20 degrees Fahrenheit, which is about three times the projected increase in temperatures over the next 75 years," Craine said. "That's a pretty extreme difference and beyond the worst-case scenario. But it is a clear indicator that long-term warming will affect bison and is something that will happen across the U.S. over the next 50-75 years."

While the economic cost of smaller bison might not be so great, Craine said that warming might also shrink the revenue of cattle producers.

Although compiling and analyzing data about cattle weights has yet to be done, findings for bison may translate to the more than 90 million cattle in the U.S., Craine said. Cattle and bison share similar physiologies and weight gain for both is typically limited by protein intake.

If the same reduction in weight gain applies to cattle as bison, every temperature increase of one-and-a-half degrees Fahrenheit could cause roughly $1 billion in lost income for cattle producers, Craine said. The reduction would come from either the cost of protein supplements needed to maintain similar weight gains before climate change, or from a loss of income because of reduced weights. Scientists predict that temperatures in the U.S. will increase by 6-8 degrees Fahrenheit during the next 75 years.

The study is an offshoot of Craine's ecology research with the Konza Prairie Biological Station, which is jointly owned by The Nature Conservancy and Kansas State University. Managed by the university's Division of Biology, the Konza Prairie spans about 8,600 acres.

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Cork Meyer    
Wyoming  |  June, 21, 2013 at 12:30 PM

This is totally propaganda passed off as genuine science. I have been on ranches in Texas, Arizona, Colorado and Wyoming and have known for 30 years that southern cattle and horses are basically smaller because they have to eat so much more to get the same nutrition. But beside the facts just the name of the backers of this study tells a much larger story, The Nature Consevencie and Ted Turner, these two make this story MOOT

Kansas  |  June, 23, 2013 at 07:53 AM

That's great that you have observed the same thing for cattle and horses. What is amazing is that no one has ever measured it for them like has now been done for bison. The hard part with research like this is making sure the patterns are most likely caused by climate and nutritional quality. There are a lot of other differences between Wyoming and Texas grasslands and grazers. It is important to note that the reason that these animals are smaller in the southern grasslands is not that they eat more, but because they eat less. Low-quality grass takes longer to digest, which reduces intake rate. This research was not funded by Nature Conservancy or Ted Turner. They only provided access to data. If you look, no one funded it. Still, scientific results should never be judged by funding sources.

indiana  |  June, 21, 2013 at 05:03 PM

They cant tell if going to rain tomorrow, but they know the weather 50 years from now. BULL.

Wyo  |  June, 21, 2013 at 06:42 PM

TOTAL BS (bison or bovine or bull). The measurements and raw data may be fact...........his conjecture about the future is the BS.........or BW......brainwashed.

S. Dakota  |  June, 22, 2013 at 09:35 AM

Frame score would have been a much better measurement to use, rather than raw weight. A small fat buffalo (or bovine) can weigh more than a big skinny buffalo. I wouldn't go so far however as to throw out all of the good science regarding global warming, which is overwhelmingly real and manmade. I would agree that this particular study, like so many out there today, started with global warming (sorry-climate change) then set out in search of data points that could be manipulated to point to a predetermined answer. There is a lot of really good science supporting climate change, but there is also a lot of science out there today that is drawing the land from the map rather than drawing the map from the land.

California  |  June, 22, 2013 at 10:26 AM

Craine is right to point out the vital importance of bison. Where the heck would brucellosis and bovine TB find a ready reservoir without bison wandering loose and too sacred to be managed for disease? Without bison and cervids we risk extinction of brucellosis and bovine TB from within the borders of the U.S. and that would be a crushing loss of biodiversity probably. And it stands to reason bison would be the canary in the coal mine when it comes to climate change. I mean, they are pretty sensitive to their environment, right, like how they fell to lead poisoning back in the days of the wild west. Just one little whack from a Sharps and even the biggest bull folded like a cheap lawn chair. Yes, we definitely should exploit myths surrounding the American bison to gin up our irrational fear of climate change. They are like the polar bear of the plains, I suppose. God, I hate these sold-out former scientists now bloviating for grant money. Too bad climate change isn't crushing them. Instead they grow fat and stupid from all the $$$ pushed to them by all the panic they pander to.

indiana  |  June, 22, 2013 at 11:58 AM

Read The Mad, Mad, Mad World of Climatism by Steve Goreham. Man made climate change is a BULL.

Kansas  |  June, 23, 2013 at 08:01 AM

Almost no one has been recording hip heights for bison. It would have been good to get this with weights, but unlikely would it have been better on its own. There is still more to learn, though. How do you know that the work started with a particular goal? It didn't. If you think that the conclusions are in error, it shouldn't matter what the initial motivation was for the work. Can you lay out an argument for why the conclusions (bison would get smaller with warmer climates) should not be connected to the findings (bison are smaller in places with warmer climates)?

Kansas  |  June, 23, 2013 at 08:07 AM

Hip heights or shoulder heights would have been good data to have, too. Though unlikely would they have been better. There is still more to learn. How do you know what motivated the work? Can you tell that it started with a goal of a predetermined answer? Are you sure of that? Or is it easier to question a person's motivation than it is to address the science? If you feel that the conclusions (bison will be smaller as climate warms) are not supported by data (bison are smaller in warmer climates), where in the chain of data and reasoning is there an error?

Kansas  |  June, 23, 2013 at 08:15 AM

Do you think that bison are more sensitive to environment than cattle? or less? Is warming going to impact cattle more than bison? No grant money was spent on this project. Again, supposed motivations are easier to question than actual science. It also doesn't seem right to hate people you haven't met. Probably is best not to hate people you have met.

VA  |  June, 24, 2013 at 08:35 AM

15 years of cooling and now all of a sudden it is going to start warming, big-time, right? Oh, and when it starts warming our bison are going to get smaller, right? We will wait and see. While we're waiting, the earth continues to cool and your religion is falling apart. I have no doubt that you will find another crisis though.

ND  |  June, 24, 2013 at 10:59 AM

In drought years our calves get heavier, grass is shorter, protein higher. Back in 74, there was the first earthday . Mother earth was going to be destroyed by now. Today it's global warming, but it is going to get cool soon beause of global warming. And by the way is ok to dislike people we don't know. What is war about?

KS  |  June, 25, 2013 at 06:43 AM

There is no evidence that there has been 15 years of cooling. The pace of warming on land has been uneven, but no one expected it to be perfectly smooth. 2012 was still the hottest year on record for the US. One question to ask is what evidence is required to believe that the Earth is warming? It is one thing to not believe what people say, but what would it take for people to agree? One important thing is that people need to keep track of weights so we can see if weights are declining or not. We do not know how fast this would happen.

KS  |  June, 25, 2013 at 06:53 AM

LAP-- Good observation. In KS, we found that if it was a wet year or a dry year, bison gained the same amount of weight. What mattered was when drought hit. Drought in June, heavier animals. Drought in August, lighter animals. As far as we can tell, that doesn't happen in Montana. Still, it would be great if people would record weights every year and compare that with weather to better understand how weather impacts weights. Others would say that drought years also lead to lighter animals. I wouldn't judge today's scientists based on what was said in the 70's. No one mistrusts doctors about cancer because of what was thought about the disease 40 years ago. Scientists have known since the 1800's that adding CO2 to the atmosphere makes the planet warmer. Understanding the relative importance of all the factors that influence temperature has required modern computers and really wasn't possible to begin to figure out until the mid 1980's.


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