Birth Synchrony refers to the short period of time in the spring during which most buffalo calves are born. Typically, the main birthing season occurs within three or four weeks in spring, even though bulls may run with the cows all year around.

In the long history of Buffalo evolving on the plains of North America, birth synchrony is considered an adaptation that insures that most calves are born at the time they are most likely to survive. This applies to Plains Buffalo and probably even more acutely to Wood buffalo of the far north.

Because of long cold winters, the window of time for optimal survival of buffalo calves is especially short in the far north reaches of Canada where Wood buffalo live on the open range. Often pregnant cows come through winter in a semi-starved condition.

Then almost suddenly grass greens up. It’s the birthing season. Winter semi-starvation gives way to spring’s tender and nutritious plant growth.

This provides the best food of the year for mothers and their young calves. Milk production is at an all-time high soon after mothers give birth.

Birth Timing Relates to Seasonal Changes

Scientists who study birth synchrony in buffalo find evidence that the timing of giving birth is strongly related to seasonal changes in their food supply and quality. The timing of birth is important in survival.

Yet the mothers generally get bred during warm fall days. Who knows when spring green-up will occur? And it varies widely year to year.

Another factor in the tightness of Birth Synchrony may be the presence of large predators such as wolves. In areas where wolves threaten buffalo herds with big, ruthless packs—as was the case for all buffalo thousands of years ago—it is much safer for a calf to be one of many other calves in the middle of a herd.

August and September are the months when mating occurs for the American Bison. The gestation period is about 285 days long—or around 9.5 months.

Mothers usually give birth to a single calf that will nurse for about a year if she continues to have milk—or until the next calf is born. They may give birth to twins and even triplets, but it is difficult for most buffalo mothers to bond with and feed more than one calf.

Bison heifers are considered mature and can be bred at 2 or 3 years old. With good management in commercial herds today, cows can live 30 years or more and raise a calf every year.

Males reach maturity about age 3 but do not usually breed until about 6 years old—when they have grown large enough to compete with other bulls. This may depend on how many mature bulls are in the herd.

Pennsylvania State Extension recommends at least one bison bull for 10 to 15 cows. In today’s ranch herds, young bison bulls between 18 and 36 months of age are often sold for meat, byproducts and breeding stock.

This cuts down on having too many bulls in the herd and excessive fighting during rut. In open range situations, such as in northern Canada more young bulls may remain with the herds.

How Birth Synchrony Works

There are distinct advantages when most calves are born during an optimal window of time.

For instance, calving of American bison was studied at the National Bison Range, Montana, in 1982. Approximately 80% of the calves were born within three weeks–the last week of April and first 2 weeks of May.

Thus in a herd of 100 cows, most of which raise a calf every year—as in well-managed commercial herds today with good grazing conditions and safety from predators—nearly 80 calves might be born during the last week of April and the first 2 weeks of May.

Another 5 calves might be born earlier and 15 later, perhaps dragging out until the end of July. Although in some cases the last calf delays until September or even December.

During that time at the Bison Range, cow-calf pairs grouped together with other cow-calf pairs rather than with cows without calves.

Was this banding together a natural defense against predators, even though there may no longer be viscous wolves in the vicinity at all? Well fed, the powerful bison mothers were well prepared to fight off attacking bands of wolves and coyotes.

However, scientists say climatic factors appear to be the best explanation of birth synchrony in bison.

Parturition: The Process of Birth

Parturition means the process of giving birth—also known as labor. It signals the procedure of delivery after the completion of pregnancy. The developed calf is born with the release of cortisol.

During parturition the cervix dilates and relaxes. Along with cortisol, oxytocin and estrogen hormones are released to begin the milk production and the process of birth.

The uterus contracts to push the fetus toward the cervix and continues until the fetus comes down the birth canal.

After parturition, the uterus releases the placenta and it passes out immediately after the calf is born.

The afterbirth or placenta passes out right after the calf is born. He’s soon up looking for milk and gaining strength in his running legs. NPS.

The first milk is called colostrum and lactation begins. This milk contains antibodies, which is required for newborns to protect them against infectious diseases.

Are Baby Buffalo Hiders or Followers?

This “follower” strategy—which contrasts with hoofed mammals such as elk and deer whose young initially hide under cover —makes sense for bison and many other open-country ungulates, given how exposed their offspring are.

Some smaller grassland grazers, however—including mule deer and the pronghorn antelope that share the American plains with bison—are “hiders” as newborns.

In American Bison: A Natural History, zoologist Dale Lott noted that infant bison usually take no longer than seven or eight minutes to stand up.

In that narrow window of relative helplessness, however, a freshly delivered baby buffalo certainly makes a tempting target for a coyote or wolf. But as recent Yellowstone incidents demonstrate, the presence of a horned, half-ton mother is usually enough to thwart predators.

Bison cows often isolate themselves to give birth, but once the calf is able to move, the pair rejoins the herd. A newborn moving about within the group is already that much less vulnerable than if they are hiding in the grass.

Mother stays close to newborn, as she grazes in the sagebrush.

In Wood Buffalo National Park on the boreal border of Alberta and Northwest Territories, wolves—a much more formidable potential bison predator than a coyote—selectively target bison herds with calves in early summer, but youngsters often escape by fleeing within or in front of the herd, or are saved by an active, belligerent defense from both cows and bulls.

National Parks in Northern US

During a five-year study in Badlands National Park, SD researchers recorded the onset of parturition by Plains Bison between April 3 and 7, with a median birth date of May 2–8.

In Wind Cave National Park, South Dakota, they reported the first births of bison on April 4–7, peaking in late April or early May; although varying among years, the mean length of the birth season, which they defined as period over which 80% of births occurred—was 53.7 ± 10.2 days.

In mountains and badlands, calving is often monitored by aerial count from airplane or heliocopter.

In Yellowstone National Park, Wyoming, predicted parturition has varied widely among years and herds, with the onset occurring from March 31 to April 12 and April 10–27 for the Northern and Central herds, respectively.

The median date of parturition for these herds differed by 16 days (May 6 and May 22), indicating variation in the timing of births even among closely adjacent populations.

In all these populations of Plains Bison, the length of the birthing season varied annually, but largely began in early April and concluded by mid- to late June.

A few calves were born abnormally late, including into September for most studied populations of Plains Bison, and, in exceptional cases, into November in Wind Cave and Yellowstone national parks.

Canada—The Yukon

The birthing season for ungulates (which are primarily large mammals with hooves such as bison, elk, moose and caribou) living at high latitudes is short. In northern North America, birth for most of these occurs within four weeks, beginning in mid-May, peaking in late May, and tapering off by mid-June, according to research in 1998.

Where the environment is distinctly seasonal, there is strong selection toward synchrony or grouping for births—both within and between species—likely in response to a short growing season and, perhaps also the pressure of large predators.

Births outside this “birth pulse” is of interest because it aids in better understanding the stretching out in the timing of births. Alternatively, it may reveal a faulty adaptation if survival or fitness is compromised for early or late born animals.

The timing of parturition in high-latitude populations of Bison is not well studied—and much of the documentation was done in aerial surveys at some distance since these are free-ranging buffalo in the mountains.

But previous observations have indicated that births do not start until mid-May and largely end in late June or early July, similar to those of other far northern grass-eaters.

In three high-latitude Bison populations in northwestern Canada, the onset of parturition (births) occurred as early as late March and early April—5–6 weeks earlier than previously observed—and two isolated cases of late births occurred in mid-November and mid-December.

These observations suggest that the onset of the birth process in high-latitude Bison can be earlier than previously known, and late births, while apparently rare, may occur.

Determining whether this signals a substantial, lasting shift in the timing and, possibly, synchrony of parturition in high-latitude populations of Bison will require further monitoring of early-born calves.

Most data on the timing of parturition of Bison are from populations at lower latitudes.

Free-ranging Wood Buffalo in Far North

Unfortunately, similar field data are not available for birth dates of free-ranging Wood Bison, which occur at high latitudes, where seasonal constraints are more pronounced.

Geographic variation in the timing of Bison births has been postulated, with the onset of parturition and median birth date later and synchronicity, or tightness of births greater in northern than in southern populations.

For mountain sheep one study found a strong link between latitude and the onset of birth, with later dates of first births in more northern populations.

Similarly, for Wood Bison, the onset of first births in Wood Buffalo National Park, Alberta and Northwest Territories, was reported as May 10 and 12. This was more than a month later than observed for Plains Bison in the US.

Anecdotal observations from field surveys in northwestern Canada over the past 16 years show that early births by Wood Bison largely occur at about the same time as that for Caribou and Moose.

However, it may start earlier, such as early May, and end later, in late June. This suggests that spring green-up of forage also strongly influences the timing of calving by Bison at high latitudes.

Births outside this period have not been observed.

Allen T. Rutberg writes in Journal of Mammalogy, August 24, 1984, “We document recent observations of unusually early- or late-born Bison calves from three reintroduced populations in northwestern Canada.

“Our observations were from the Aishihik population in southwestern Yukon, Canada and the Nahanni and Nordquist populations, which occur at the nexus of the Northwest Territories, Yukon, and British Columbia, Canada, all located between 59°N and 61°N.

“These populations were monitored irregularly by wildlife management agency personnel during the parturition period. We used the description of coat color changes in Bison calves to crudely estimate the parturition date of those born late.

Early-born Calves

“On April 4, 2013, we observed a calf from the Nahanni population, which was assumed born the previous day. In 2015 and 2016, we observed Bison calves from the Aishihik population, presumably born in early April, with the earliest calf seen on April 4, 2016.

“Further, in the first week of April 2016 and 2017, lactating females that had recently been suckled were observed in the Aishihik population.

“Based on a physical examination of the uterine tract of two lactating Bison shot during April 4–6, 2016, these females may have recently given birth.

“For a lactating female shot on April 5, 2017, the predicted birth date was possibly mid-March, based on measurements of the uterus. We note, however, that lactation itself is not unequivocal evidence that the female recently gave birth, as she may have been suckling her calf from the previous year.”

Late-born Calves

March 17, 2005

Reddish-brown calf in a group of 11 Bison near Haines Junction, Yukon Aishihik, noticeably smaller than other calves in the area. We estimated that the calf was probably 10–13 weeks old when observed and, thus, likely born in mid-December.

January 7, 2012

Small calf with a reddish coat in a group of 26 Bison near Liard River, Nordquist British Columbia, about 30–40% the size of seven other calves in the group. Based on descriptions of size and coloration and photographs, we estimate that the calf was probably 8–10 weeks old when observed and, thus, was born in early to mid-November.

Bison born late were rarely recorded; however, we documented two instances from two populations in northwestern Canada. These calves were substantially smaller than other calves observed, and pelage color also differed. Based on descriptions of size and coloration and photographs, we estimate that these calves were born in mid-December and early to mid-November.

Shifting Dates of Birth Synchrony

“Our observations provide evidence of parturition in early April, and possibly as early as late March, in at least two high-latitude populations of Wood Bison—5–6 weeks earlier than reported from Wood Buffalo National Park and earlier observations for the Aishihik and Nahanni populations by wildlife management agency biologists and conservation officers.

“It is uncertain whether the earlier onset of parturition has occurred previously and gone unnoticed or if there has been a shift in the date of first births in recent years.

“We believe that the latter is more plausible, given that observations of Bison in late March and April by wildlife management agency personnel, Bison hunters, and local residents have not included any reports of calves born earlier than May before 2013.

“Detailed studies of the timing of parturition in Plains Bison in more southern and other ungulates, such as wild sheep provide evidence of annual variation that may exceed 2 to 3 weeks.

“Moreover, the onset of parturition in Bison at Yellowstone National Park has shifted from late March to mid-April over 55 years from 1941 to 1997, demonstrating that changes in the timing of parturition for Bison can occur over longer time scales.

“Whether the early births we observed indicates a shift in the timing of parturition in Bison from the Aishihik population is unknown. Showing this would require further monitoring for early-born calves

“Although the onset of parturition in southern populations of Plains Bison normally occurs around early April to match the food availability, early births in the Aishihik and Nahanni populations have occurred while temperatures were below freezing at night and patches of snow persisted on the ground, indicating a mismatch between early births and spring green-up of forage resources.

“Generally, calves born earlier in the season may have an advantage over their cohorts that may last their lifetimes, but those born early in suboptimal conditions, possibly because their mothers were in poor body condition, may not have an advantage. In the latter case, the prognosis for their survival is poor.

“Similarly, the fate of late-born Bison is unknown. However, the late-born calves observed had survived the critical neonatal period (the first month after being born) during early winter at high latitudes, indicating that they may survive the rest of the winter.

“In other instances of late-born calves, it has been assumed that the mother was in poor physical condition during the peak of conception and bred later in the season when her body stores had increased. However, the fate of these early- and late-born Bison is unknown.

“In conclusion, our observations are of scientific interest because they provide new information on apparently extreme birth dates for high-latitude Bison, and they demonstrate some flexibility in the onset of parturition in these populations.

“It appears that parturition at high latitudes may begin in late March and, in exceptional cases, extend into December. Overall, however, the timing of parturition for Bison appears to be largely synchronous with spring green-up, albeit with a wider range of dates than for other ungulates in the region.”

Hmm. That’s interesting. As the resident of a northern state, I’m wondering. People who live here know well that spring green-up doesn’t always arrive at the appointed hour or date.

Hard winters sometimes hit—and bring a late spring. An easy winter might mean an early spring. Or quite the opposite.

In the Yukon weather might be even more extreme and unpredictable. So is there some leeway on how many gestation days occur? When spring comes early does gestation speed up to less than 9.5 months? And hard winters with late springs drag births out longer?

Someday will researchers link dates of first green-up with Birth Synchrony and tell us about the weather when Buffalo declare an early spring? Or a late one?

Studies of the timing of births in Plains Bison in more southern latitudes and other ungulates, such as wild sheep, provide evidence of annual variation of more than 2 or 3 weeks from one year to the next. Depending on what? 

Definitions

Birth Synchrony: The short period of time in the spring during which most buffalo calves are

born. Considered an evolutionary adaptation that insures most calves are born at the time they are most likely to survive.

Parturition: The process of giving birth—also known as labor.
Colostrum: The mother’s first milk after giving birth—contains antibodies that protect

against infectious diseases.

Precocial: Means buffalo calves are born fully developed and able to follow their mothers and

the rest of the herd almost immediately after birth. They need only 7 or 8 minutes to

stand up.

Ungulates: Primarily large mammals with hooves (split or not-split) such as bison, elk, deer,

moose and horses.

Francie M Berg

Author of the Buffalo Tales &Trails blog

Feeding an orphan calf is an emergency situation. It has to be done “right now!” And it is a time commitment.

So it’s a good idea to be prepared.

Calving season has arrived and so have many new buffalo babies. It’s an exciting time of the year when new calves are welcomed to the world.

Fortunately for you who are buffalo ranchers there are usually few problems associated with calving.

However, it may happen that a calf is abandoned—perhaps the weakest of a set of twins—or the mother cow dies, or for some other reason a calf must be removed from the pasture and raised by hand.

Miller has been a leader in the Bison Association of Nebraska for many years. He has been in the bison business since 1995.

Randy’s daughter Megan Olesiak works in the Miller buffalo ranch company at NebraskaBison.com. They have a second herd, Miller Bison at Elkhead Ranch, just over the line in Missouri.

Megan told me, “You need to be careful when you make a pet of a bison bull calf. They grow up.

“One time when I was a child—we were just getting started with bison. I was sitting in the pickup with the window open. We had a pet bull and he put his head in for a treat.

“And then he lifted his head and took the door off!”

Four Generations of Bison

My almost neighbors Steve and Roxann McFarland have had about 3 or 4 orphan calves in the 20 years they’ve been raising buffalo southwest of Hettinger.

“Some others may have been born as twins and the coyotes got one of them before we did,” Steve says.

“Each bottle calf we’ve raised has had its own personality. Some learn quickly to follow a bottle, some have been pretty stubborn.”

Actually Steve grew up with buffalo as his father, grandfather and great-grandfather raised buffalo on their South Dakota ranch before he was even born.

As a 4^th generation bison rancher Steve grew up helping with bison and bottle calves. It was his great-grandfather who first bought 3 or 4 bison heifers and a bull, just to try them out with his cattle herd. His grandfather Roy improved the herd and so did his father Eugene.

Their daughter Ashley showed her bison calf as a 4-H project at our Adams County Fair a few years ago—under a new class called “Exotics.” Her’s was the only exhibit in the event that year.

Good for Ashley! She’s a pioneer!

Even as a long-term 4-H leader I have never heard of this before except in Canada—where I think Alberta has a 4-H project called “Raising Bison.” Don’t know if they have a booklet for 4-Hers to study.

I’ve seen a photo of one and have written for information, but so far have been unable to find any.

Steve says her calf was apparently a twin born around the first of May and found abandoned. Raised as a bottle calf, they helped Ashley halter break him and she showed him in August at our 4-H fair.

Roxann, Steve’s wife, says a bottle calf seems to get attached to one particular person—perhaps it imprints on whoever feeds it. Often that person is her.

“One calf got so lonesome whenever no one was with him,” she says. “In fact when he was alone he wore all the hair off his head, rubbing it along a plank in his pen.

“We tried a goat for companionship—he was full grown and we thought he could hold his own. But the little bull chased him right out of the pen.

 “We put him back in—and soon he was outside again. Then we got another baby buffalo. First time we had 2 together,” Roxann recalls.

“They bonded and hung together—Oscar and Gus, both bull calves–always stayed together even after they grew much bigger. We sold them to a bison feeder.

“They were too dangerous to keep.

“The new owner said as long as he had them, the two bulls always insisted on being close together.”

Feeding Tips

Here are feeding tips from Gerald Hauer, Bison Production Specialist, Bison Centre of Excellence, in Leduc, Alberta, from his article “Feeding Orphans,” as reprinted from “The Tracker,” volume 4, Issue 5, June 2000, in Bison Producers of Alberta.

He begins with the importance of colostrum—the mother’s first milk:

“Calves are born with no resistance to bacteria and viruses and must absorb antibodies from their mother’s first milk or colostrum to be able to fight off disease. There are high levels of antibodies in colostrum and the calf’s intestines have the ability to absorb these antibodies from the inside of the gut into the bloodstream for the first few hours of life.

“The intestine loses this ability within 4-12 hours after birth so it is very important that the calf receives its colostrum within this time period. Always give colostrum for the first few feedings.

“Cattle colostrum or commercial dried colostrum replacers can be used as a substitute for real bison colostrum which is hard to obtain.

 “Often surrogate mothers are not readily available so artificial rearing is the only option. What to feed is a common question. Bison calves have been raised successfully on cow’s milk, cow milk replacer, sheep and goat milk replacer and goat’s milk.

“There is now a commercially available bison milk replacer made by Brown’s Feeds. Sheep milk replacer is frequently used because it closely resembles the composition of bison milk.

Note: Two recommended feeds for bison babies are Bison Milk Replacer from Browns Feed https://www.hibrow.ca/browns-feed and BisonGro from Zukudla http://www.zukudla.com/milk-replacers-bisongro

“Once the calf has a good start with colostrum, it is time to feed milk or milk replacer. Some people have had good success by finding a nurse mother for their orphans. A recent article in the ‘Smoke Signals’ outlined one producer’s success with using a highland cattle cow as a surrogate mother for his bison orphans.

“If you are considering using goats to raise your calves I would recommend having them tested for malignant catarrhal fever and Johne’s disease.

“One experienced producer uses real sheep milk available from one of the few sheep dairies in the province. She reports that there are fewer digestive problems with the real sheep’s milk and is worth the extra cost.

“It would be a good idea to pasteurize the sheep milk to decrease the chance of introducing MCF virus into your calves.

Feeding Frequency

“How often should they be fed? Frequent feedings of small amounts will decrease the chances of digestive upsets. Bison calves are usually fed 4 times daily for the first few weeks and this is gradually decreased to 2 times daily by two months of age,” writes Gerald Hauer

“How much to feed depends on the size of the calf. As a rule the calf should be a little hungry at the end of each feeding. If they are allowed to drink their fill they will be prone to digestive upsets and diarrhea.

 “Experienced producers like to keep the calves a little hungry at each feeding. Most calves require about 10-20% of their body weight in milk each day. This works out to about 500-800 mL per feeding for bison calves.

“As the calves get older and the feedings become less frequent the volumes fed at each feeding can be increased.

“Once the calves are few weeks old it is a good idea to introduce them to some grain and hay or grass so they can nibble on some solid feed. By the time they are a few months old they should be eating a significant amount of feed.

“Calves can be weaned from milk at 3-4 months of age and put onto a good quality diet.

“Other tips to help keep your calves healthy are as follows: 

1. Wash the bottles and nipples after each feeding to decrease the bacterial buildup. Good hygiene can prevent problems associated with contamination of your equipment.
2. Allow access to soil so calves can lick it as this may provide some nutrients.
3. Salt and minerals should also be available.
4. Build a pen that allows lots of room for exercise.
5. Try not to keep one calf by itself. Provide another calf to keep it company.

“Raising an orphan bison is a lot of work. Before undertaking the job you should become familiar with the husbandry that is required. “

For more information Hauer recommends the following “Bison Breeder’s Handbook, National Bison Association; Bringing Up Baby,” by Peter Haase, Smoke Signals, April 2000. www.bisoncentre.com › feeding-orphans

Imprinting and Sucking

 “The Journal of Buffalo Science,” published in Canada says it is important that mother and calf are able to bond immediately at birth. In the article “Imprinting, Sucking and Allosucking Behaviors in Buffalo Calves,” 2018, 7 (Lifescience Global), Patricia Mora-Medina, from the University of Mexico (UNAM), Fabio Napolitaano, U of Basilicata, Italy et al write:

“From the perspective of the [buffalo] offspring, recognizing their parents is essential for their welfare and survival, since the dams feed only their own young.

“This learning process, defined as imprinting, occurs in a sensitive period under the control of oestrogens and oxytocin, which are abundantly produced at parturition (birth).

“After a few hours the level of these hormones lowers and dams become unable to develop appropriate maternal behavior toward the newborn calves.”

“The amniotic fluid that covers the newborn is attractive to the mother and while licking they learn its specific odor thus promoting the mother–young bond. Lack of amniotic fluid may cause rejection of the newborn.

“The most important aspect of the birth process is that calves must quickly locate the udder and begin to suck their mothers’ milk. Suckling and the maternal care for calves allow them to survive and grow.

“As the calf passes through the birth canal during parturition it generates cervical-vaginal stimulation that activates the hypothalamus and releases oxytocin, a hormone that acts upon the cow’s olfactory bulb. This, in turn, enables the secretion of dopamine, which initiates the sensitive period during which the dam identifies her own calf.”

After giving birth, says this source, the mother stands up and begins to lick and smell her newborn calf. In buffalo (and dairy and beef cattle) this stimulates various activities in the calf, including the respiratory center, breathing, circulation, urination and defecation.

The newborn buffalo calf raises its head and adopts a ventral-sternal posture, followed by hesitant attempts to stand on all fours, first extending the thoracic extremities, then the pelvic ones. These movements allow the calf to reach the mammary gland and begin feeding. Other behaviors include vocalizing to attract the mother’s attention as part of the calf’s survival strategy.

Given all this, say these researchers, it is essential that the buffalo mother-calf bond develops from the moment of birth and through the immediate postpartum period.

Practices like early separation and artificial rearing generate stress in both buffalo cows and calves

“In the context of these behavioral changes, the sex of the neonate seems to play a role, as female calves show faster development than male calves.”

Mixed Blessing: Triplet Buffalo Calves

 “This spring we were triply blessed with a set of triplet bison calves, reported Peter Haase, of the Buffalo Horn Ranch, Alberta, Canada, in April 1999.

“Actually, it was something of a mixed blessing getting three heifer calves and then being confined to the ranch with the numerous feedings. We have some experience working with abandoned calves over the years with mixed results. One of our foundation cows is bottle raised.”

“With the publicity, our babies also became poster girls for ‘Brown’s Bison Milk Replacer,’ a new product becoming commercially available. We were fortunate in that many experienced bison producers gave us advice on how to raise these girls properly.

“A bison cow normally only has enough milk for one calf, so both are compromised when it comes to competing for the limited milk that mom is able to offer. Often one calf won’t get quite enough and will begin to fall behind, while its sibling grows stronger.

“It may take only a few hours or it might take a few weeks, but the usual scenario is that one calf is left behind as a meal for the predators. In the confined pastures of a ranch, the likelihood of a cow raising twins is perhaps somewhat higher than in the wild.

Recently Peter told me that the mother was named Nakimu—and hers were the first ever reported bison triplets—all female. They were named Moon Beam, Moon Shine and Moon Shadow.

“We watched these closely. The first day the mother walked away from Moon Beam—we took her. The next day she walked away from Moon Shine. She raised Moon Shadow. The other two were bottle fed.

“The last of the bottle raised calves died in 2021 of natural causes. This is after the mother having and raising 18 calves, never missing a year until her last year.  The other bottle raised sister died in 2016 and her sister, raised by the cow, died at age 10. In fact Nakimu had 2 sets of twins besides the triplets.

“The birth of the first recorded bison triplets gave us a great deal of publicity in numerous newspapers, magazines and on two national television networks.

“From our research, we have found that most abandoned calves are twins. Are twins more common today? I don’t know, I suspect that we are discovering more twins for a couple of reasons aside from there being more bison.

“Firstly, we producers are checking our herds more closely than before, so perhaps we discover the twins before the coyotes do. Secondly, we are more careful with the bison’s nutrition and health care and this too might contribute to more twins.

“We had a situation with our second calf ever being born. This calf was born at night and in the confusion of 60 heifers, the heifer calf bonded with a young cow who already had a two-week old calf.

“The new mother was frantic looking for her calf and the other cow was running around with two calves. After about 30 hours she didn’t want anything to do with this calf and abandoned it.

“We grabbed her calf at that point, gave colostrum and bottle raised her for three weeks before she died of Navel Ill. The colostrum we gave was too late and did nothing for her immune system.

“The mother of this abandoned calf found another heifer calving about the time that we grabbed her calf. She bonded with the new calf and this calf sucked on his ‘twin’ mothers all summer.

“The lesson here is that the calf must have colostrum in the first 6 to 12 hours or its chances of survival are slim.

“Another note here, we have a five-year-old bottle-raised cow that we purchased as a calf. One thing she really lacks is mothering ability.

“She never licks off her calf, nor does she look out for it very well. Fortunately, she has had two very persistent calves who have done very well despite the shortcomings of their mother. There is more to being a mother bison than instinct, there must be something learned as well.”

Carrington Bison Research attempts Alarming Rescue

Bison Research conducted at the Carrington Research Extension Center, North Dakota State University for a few years, published a report in 2001 on “Managing Very Young Bison Calves,” by Vern Anderson, Dale Burr, Tim Schroeder, Chris Kubal and Eric Bock.

The researchers worked frantically for many weeks trying to keep 69 bison calves of all ages alive. They concluded:

“It appears the success rate is very low when caring for orphan bison calves under the age of 4 weeks unless significant individual attention can be given to each calf. 

“These animals are simply too dependent on mother’s milk and cannot be acclimated to milk replacer and starter feeds as a group. 

For their research the Carrington Center accepted a donation of 69 bison calves ranging in age from two days to two months, delivered on June 4, 2001. Their mothers had been managed as feeder heifers and were scheduled for market. Some had been bred accidentally.

“At the time in 2001 there was virtually no nutritional information or guidelines on the care of baby bison prior to weaning,” says Dr Vern Anderson.

“Consultation with a number of experienced bison producers suggested we had a major challenge on our hands.”

Turned out they did indeed! It was a desperate situation for the researchers. All of them working every available minute to save all those calves.

It probably couldn’t be done with the manpower available. But they met the challenge as best they could.

First they separated the 16 youngest and smallest and kept them in a small fenced area, while the older calves moved to a one-acre grass pasture.

“Catching these youngest animals, even in a small pen, proved to be a challenge. At the young age of the calves, they were fast and strong and fought being handled. Roping calves caused severe stress from chasing with some choking and shock resulting when calves were caught.

They refused to suck from a bottle. None of the calves adapted to that even after several days.  None of these younger calves survived to the end of their first month. The experience turned out to be very stressful for handlers and calves.

“Handling (catching, ear-tagging, drenching, bottle-feeding) any age of orphan calf is very stressful,” says their report.

“Most of the 16 simply starved to death. They were unwilling to nurse or fought the tube at every opportunity and did not learn to eat the dry feeds.”

Food was a problem for the older calves, too. The researchers kept changing the rations. The calves seemed to prefer barley malt pellets—which were low in protein and calories.
Barley pellets were then mixed with com, peas and wheat middlings to increase the nutrient density. Then the barley was withdrawn.

“Some commercially available, very palatable, high-protein, high-energy feeds were offered in three pans inside the pen. Two pans were used for milk replacer and fresh water was available in two others. A high quality grass hay bale was also available.

Finally on June 27, a specially formulated baby bison feed was introduced, developed by Heartland Feeds (Hubbard) at Bismarck, ND for use in this study. This new formula was more nutrient dense than the commercial starter feeds with higher protein (24%), more energy (est. 95% TDN) and less fiber.

It was a fortunate combination of field peas, corn, canola meal, com distillers dried solubles, soybean hulls, dried milk powder, molasses, yeast, fenugreek and highly bio-available vitamins and minerals.

Once they were used to this food it replaced all the commercial starter diets. At last the older calves seemed to bloom and their general health improved. The researchers wrote their opinion that having this nutrition from the start might have reduced stress and increased survival rate.

“Calves this old probably start ruminating and have the ability to survive on more traditional feeds,” they said.

Only 25 of the 69 ultimately survived. But by September 10, they appeared in good health and were transitioned to a conventional grain mix, less nutrient dense and lower in cost, 16% crude protein and approximately 80% TDN. This included corn, peas, soy hulls and wheat midds plus vitamins and minerals, offered with free-choice alfalfa hay.

Unfortunately the bottom was already falling out of the bison market by then, and after producing some remarkable pioneer research at the Carrington Station the bison studies came to a halt and were never restored.

Buffalo Handler Learns the Language

Another almost neighbor of mine is Jim Strand who manages the sizeable Blair Johnson herd of about 400 cows, southeast of Hettinger a few miles into South Dakota, where he’s had 8 or so orphans over the past 25 years.

Jim feeds lamb milk replacer because it is richer than cows’ milk. He also feeds at least 3 times a day. The last calf he had took to the bottle right away when born.

The mother of another died when the calf was about 3 weeks old and wouldn’t take the bottle, so Jim put him in with some feeders and he did just fine. I think he spends plenty of relaxed time with them.

Usually bum calves get attached to one person. Jim says he grunts like a buffalo to them and they seem to respond.

One time a friend needed to catch a rather wild buffalo calf and Jim went to help. “I’d grunt to him and he’d come a little closer. I kept coaxing and he came right up to me. I grabbed his foot and held him.

If I get one in a pen, I can usually coax, grunt and corner them.”

One pet they had was Lucky. He enjoyed being petted and talked to—the first year he stayed in the yard close to the family.

“He’s still in the herd. Now that he’s grown he still comes up when I’m around, but he doesn’t want you to pet him.”

Another pet was given him from a family in Bemidji, Minnesota. Raised there on a bottle. She got too big for them before she reached a year old, so they gave Jim a call.

Her name was LaBelle. She comes right up to him in the pasture and will take cake from his hand.

“She had a calf as a 2-year old—that’s unusual,” says Jim. “And she’s had a calf every year since—6 calves in a row.”

Twins-More Work, Well Worth the Effort

When twins are born, it is worth the extra management effort to save both calves, Dr Roy Lewis, a veterinarian, told producers in the March 12, 2018 issue of Grainews.ca in Canada, writing on “Problems and Benefits of Twin Calves.”

“In my practice, I often hear producers complaining about twins,” he wrote. “Mainly because often the focus is on the problems they can present.

“About 8% of most common beef breeds will produce twins and it is also quite common among bison.

“Economics show there is value in making the extra effort to save the extra calf.

“Research on a twinner population over the last 10 years in the U.S. found there to be a definite economic benefit with twins. So it is important to look at both the positive and negative aspects hat come with these double deliveries.

 “There is no doubt twins can be a positive if they both arrive alive, are the same sex and you have an extra cow to foster one of the calves.

“But we all know the opposite—twins coming malpresented, then you finally get them out (with or without veterinary assistance). Both are dead and the cow doesn’t clean and becomes a problem to rebreed.

“Dystocias (birth difficulties) from fetal malpresentation are the biggest reason twins have a lower survival at birth.

“When one ponders the combinations of all the legs and two heads coming backwards and forwards, it is no wonder mixups occur.

“If we can minimize the bad scenario and come up with more positives, twins would be welcome. Keep in mind they will always require more care, attention and management skills.

“It’s important to watch the cows and calves closely and jump in when problems develop,” he writes.

An Alberta-based veterinarian specializing in large-animal practice, Dr. Lewis has served as a part-time technical services veterinarian for Merck Animal Health. He is involved in planning the International Bison Convention to be held in Saskatoon, Saskatchewan, July 12-15, 2022.

Dr Lewis served on the committee updating the National Canadian “Code of Practice for the Care and Handling of Bison.” That publication which was released in 2001 and updated in 2017 tries to discourage making pets of bison.

“Bison should not be raised as pets,” the Canadian Code states bluntly. “Producers opting to rear orphans should refrain from playing with calves. Bunting behavior should be discouraged at all costs.

“Adult bison that have played with humans as calves may become dangerous. Orphaned bison must not be used for breeding under any circumstances. Castration and dehorning is strongly recommended for orphans. Orphans may be able to be reintroduced into a feeding program.”

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Francie M Berg

Author of the Buffalo Tales &Trails blog

Brucelosis has a devastating effect on cattle, in that infected cows abort their first calf, and sometimes the infection stays in the system for years. The disease also infects Bison and elk.

 European cattle initially brought the bacteria Brucella abortus to the new world. The disease especially spread through dairy cattle, but wild bison and elk in the Greater Yellowstone Area became infected with the disease before the 1930s.

The  brucellosis vaccines available today are considered only 65% effective for cattle and even less so for bison and elk.

It’s complicated. And because they are live vaccines, they can bring the infection itself.

Heifer calves need to be vaccinated before the age of 12 months. Otherwise, if any are pregnant at the time of vaccination, they may abort and potentially spread the disease to herd mates or even people getting in contact with the aborted fetus and placenta.

There is hope of better vaccines to come, but it may be quite a long time.

New vaccines are under development at several University research labs, according to The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS), which is in charge. Their website on brucellosis states:

“Unfortunately, we lack not only a proper treatment but also a reliable diagnosis.

“Adequate and timely diagnosis of brucellosis is necessary to control and treat the disease in the best way. Different serological and molecular methods are used for the screening of the disease. However, each test has some drawbacks in one way or another.

“Vaccination is an effective strategy to prevent the spread of brucellosis and is in practice worldwide.

 “However, there is demand for the development of new vaccines that are safer and more effective.

“With rising interest of the scientific community in brucellosis, a significant improvement in diagnosis and treatment is expected. We are also in need of a broad-spectrum vaccine against Brucella for complete eradication of the disease worldwide.

“APHIS continues to support brucellosis research at universities and is also working with USDA’s Agricultural Research Service to further study RB51 vaccine, and to develop alternative brucellosis vaccines that would be more effective in wild bison and elk herds.

 “Current vaccines are about 65 percent effective. It is unlikely that new vaccines would protect 100 percent of vaccinated animals. However, new vaccines may provide additional protection for the animals and help reduce the incidence of the disease within the herds.

“APHIS is also involved in studying the brucellosis disease agent—how it is transmitted and shed by infected animals into the environment.“

“It took a huge effort in eradicating this disease from cattle in the United States. But as of March 1, 2002, nearly all states have achieved brucellosis-free status with no known infection.

“The only known focus of Brucella abortus infection left in the nation is in bison and elk in the Greater Yellowstone Area. However, this has been a tremendous problem for ranchers in nearby areas of Wyoming, Montana and Idaho.”

Until all brucellosis is wiped out—there will continue to be great problems and controversy in the Yellowstone Park area.

How does Brucellosis Infect?

Brucellosis is primarily spread within and among bison, elk and cattle during calving season when susceptible animals ingest Brucella bacteria from birthing materials (amniotic fluids, fetus, placenta) or the newborn calf.

Mother elk clean up most of it when they calve outside the park, and scavengers consume most of what remains. But perhaps not all. A secondary mode of infection is through the milk when actively infected females nurse their calves.

Females are often infected with Brucella bacteria at a young age, but do not shed the bacteria until they become reproductively active at around age 3, when conditions become favorable for bacteria to multiply and spread in the reproductive tract during the last months of pregnancy.

At that time, the bacteria can rapidly increase in cells of the placenta and induce abortions, still births, and premature live births in some animals.

Some females appear to recover and clear the bacteria from their bodies after this initial pregnancy, but others retain the infection and can become infectious during additional pregnancies.

Infected male bison shed Brucella bacteria in semen, but do not infect females during breeding because of the fluids in the vagina that are fatal to the bacteria.

In addition, bison and elk are more vulnerable to infection when their immune defenses are weakened, as during winter starvation. Risk comes primarily in February through June when most brucellosis-induced abortions occur.

Brucellosis in Humans

In humans, brucellosis–also known as Bang’s disease—is called undulant fever, human brucellosis or Malta fever. It is world-wide in distribution.

According to the Journal of the American Medical Association infections may spread to humans through cuts or bruised skin or infected milk. It evidently does not affect the meat, which may be eaten.

People with undulant fever may suffer weakness, headache, painful joints, loss of weight and appetite, alternating chills and fever, profuse sweating, sleeplessness and numbness of arms and legs. It is seldom fatal, but can become chronic or long-lasting and weaken resistance to other diseases.

More than $3.5 billion has been spent since 1934 to eradicate brucellosis from cattle in the United States.

My husband Bert was part of this program, spending his first summer after college graduation in 1953—before continuing his Veterinary Medicine studies—testing North Dakota cattle herds for brucellosis.

During that time he was diagnosed with undulant fever. But although it stayed in his system long-term from that experience, he was generally able to ignore his symptoms.

Bert was most saddened though, by infected cattle herds that had to be condemned. It was the only way of eradicating the disease.

Low Point in Buffalo Numbers

The lowest point of buffalo numbers in Yellowstone Park was probably around the turn of the century.

In 1916 the original bison were counted at only 23 head. That’s when park managers began their first efforts to save bison as an endangered species.

Many people today, researchers as well as others, seem to believe these were Mountain or Woods buffalo and they are calling today’s Yellowstone Park buffalo a hybrid of the two subspecies—Wood buffalo and Plains buffalo.

I very much doubt whether that can be true.

Apparently, those bison were counted in the summertime, and likely included a few calves and young animals. So they’d have had relatively few fertile cows and I doubt that they would have birthed many calves.

Also the Wood bison probably would not interbreed widely, since they tend to be shy and scattered.  

 In fact, those early herds as well as those introduced could have been simply the wilder Plains buffalo that had found remote mountain canyons to hide from relentless hide hunters—as surviving bison did throughout the west.

Is it really logical to assume that the two—Wood and Plains bison—interbred widely to form a new hybrid subspecies?

 Possible, of course, but probably wishful thinking on someone’s part.

Soon Excess Numbers Needed Culling

Since 1932 the buffalo in Yellowstone Park have been periodically culled to keep the totals down to a reasonable number for good grazing and to balance the needs of other grazing wildlife.

Eventually the YP bison numbers were targeted at around 3,000 in the Park, although they often reached nearly 6,000 before culling.

After 1960 the culling operation became better organized. As many bison as possible were herded by two coordinating helicopters into one of two traps—the Crystal trap at Lamar in the northeast quarter and Nez Perce trap on the Firehole River nearly 35 miles farther southwest.

By the winters of 1964-65 and 1965-66 squeeze chutes handled most of these trapped bison and they were either sorted for release or trucked to a local slaughterhouse, according to Margaret Mary Meagher, Research Biologist of the National Park Service, author of “The Bison of Yellowstone National Park,” 1973.

Most were aged by Department of Agriculture veterinarians and weighed. Also 47% of the animals removed from the park were examined for pregnancy, abnormalities, and evidence of injury or disease other than brucellosis.

Selected for butchering were bison with brucellosis suspected as well as those with abnormalities and injuries. The meat from healthy animals was packaged, frozen and delivered to Native tribes.

However, reproductive tracts were not examined, because about half of removed bison were brucellosis suspects.

Department of Agriculture veterinarians advised staff against such exams of reproductive organs, where the Brucella organism localizes, to avoid contamination of slaughterhouse premises and exposure of personnel to the disease.

All animals were permanently metal ear tagged and marked with temporary backtags, which were visible even from an airplane.

Fertility control along with culling is being considered in limiting the bison population in Yellowstone. For example, one type of contraceptive vaccine being investigated for possible use in bison would form antibodies that block sperm from fertilizing eggs. Another prevents follicle growth and ovulation.

However, available methods fail to be affordable, very effective, reversible or easily delivered to wild bison and elk that are spread across the vast landscape that is Yellowstone Park.

Further, they would likely have unintended consequences—such as altering the behavior and physiology of wild bison by changing the herd’s age structure.

USDA is charged with eradicating brucellosis from the United States and also remains committed to maintaining a viable and free-roaming bison herd in Yellowstone National Park.

(For more information on attempts to solve this problem, see “Part 1—InterTribal Buffalo Council Restores Herds—and More,” and “Part 2—ITBC, 30 years—Yellowstone Bison Dilemma,” blogs by Francie M Berg, Dec 29, 2020 and Jan 12, 2021. One solution has been quarantining young Yellowstone Park bison that test negative for brucellosis, raising them fenced away from the herds for as many as 5 to 8 years, while annually testing and finally allowing them to join specific tribal herds under strong fences.)

A New Plan gets Underway

A long-term plan for moving ahead with these issues is being made. The new plan includes both ranching and tribal interests at the table.

Of course, it’s difficult. The time for inviting public comments ended the last of February 2022.

Indian tribes today are insisting on what they see as their rights. Mostly they want to stop the butchering of excess bison in Yellowstone Park. They also do not want the bison altered in any way.

Instead, they’d like to bring the excess animals into their own buffalo herds. Many revere the Yellowstone Buffalo for their history as the last wild bison in America.

Indeed some tribes can point to treaties in which they were promised they could hunt and be in control of these areas “as long as the sun shines” or basically forever.

Certain tribes are allowed to hunt bison as they come out of the Park. Many environmentalists and others agree that is only right.

Cattle ranchers in the area are appalled by the idea of free-ranging elk and bison—which are both frankly considered to be about 50% infected with brucellosis—grazing the same ranges outside the Park in the Yellowstone area, even if at different seasons.

So far they’ve been able to get the Montana Legislature to agree with their rule: “To not allow live bison to leave the Park. Period.”

Thus no cattle have been reported as brucellosis infected by bison to date. No cattle are inside the Park and no bison are outside.

The wild elk are a different story. They are free to wander where they wish. Many elk leave the Park for better foraging when the snow gets too deep in the higher mountains.

There have been reports of vaccinated cattle infected with brucellosis from elk.

The experts point to the winter of 1996-97 when, with the Yellowstone Park herd at record levels, the limited forage in the Park was covered with record levels of ice and snow. Large numbers of bison moved outside the park looking for food.

Exiting the Park that winter were 1,079 bison that were then shot or sent to slaughter. An additional 1,300 or more bison starved to death inside the park because they could not paw their way through the ice.

There is a belief that bison need an area at the lower altitude outside the Park for grazing in tough winters.

“Research efforts are also underway to develop a safe and effective vaccine delivery system so that bison can be vaccinated remotely, as opposed to only hand injection,” according to the APHIS plan.

“In addition, APHIS has a veterinarian with wildlife management training and experience stationed in Montana, to function as a liaison among involved government agencies.

“APHIS is confident that, as more activity is generated on this issue, this liaison position will become increasingly important in ensuring that all involved parties are informed and that APHIS’ involvement is coordinated.

 Can Brucellosis be eradicated from Yellowstone wildlife?

 “Yes,” replies APHIS to its own question.

“APHIS officials are confident, based on experience in other public and private bison and elk herds and on other successful disease eradication programs, that use of a combination of disease-eradication and herd-management measures will lead to the successful elimination of brucellosis from bison and elk in the Yellowstone ecosystem.”

Wow! They sound pretty confident—but it’s clear this will not happen soon.

 “Currently the best alternative for wildlife and livestock managers is to suppress the probability of Brucella abortus transmission by maintaining separation between bison, elk, and cattle during the period from February through June when calves are born and bedgrounds are being infected,” say USDA officials.

 The new plan for how this might be accomplished will soon be announced—and you can be sure we will report it to you in our blog.

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NEXT: Saving Orphan Buffalo Calves

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Francie M Berg

Author of the Buffalo Tales &Trails blog