Behavioral research at the Ferme des Bisons in the Belgian Ardennes:
where science meets industry.
Hilde Vervaecke1 & Jean-Francois d’Hoffschmidt2,
1
: KAHO Sint Lieven, University College, Agro- & Biotechnology, Ethology & Animal Welfare, Hospitaalstraat
23 B-9100 Sint Niklaas, Belgium: [email protected]
2
: La Ferme des Bisons, Recogne, B-6600 Bastogne, Belgium: [email protected]
American bison have found their way to Europe. In several European countries, the
number of bison on commercial farms are still modest and relatively stable. At present,
France counts 1344 bison, Denmark 1100, Germany 1100, Switzerland 500, the United
Kingdom has about 400, Belgium 400, Bulgaria, Rumania, Austria, Poland, Sweden, and
Finland have about 200 animals each. The “Ferme des Bisons” is one of the largest and
earliest American bison farms in Europe founded by Jean-Francois d’Hoffschmidt in the
Belgian Ardennes. Most traditional farmers tend to consider scientists as a hassle that
should be avoided. Scientists can take up time and usually don’t bring in cash. They are
known as critical persons and discretion may not be their primary characteristic. They
extract information from your company, they know about your losses and successes, and
who knows how all this can be used? No scientists, no hassle, no risk is one strategic
option. Other options range from quietly allowing scientists to move about your farm to
fully embracing science. Some scientific projects can be economically relevant. When
animals are threatened by disease or parasites and the treatment needs to be optimized,
a relevant veterinary project may be welcomed. Research on various economic models,
e.g. with a variation of management decisions such as age at slaughter, age of culling
etc. and the expected return, may directly boost the dollars. This is the sort of science
that serves the industry. The resulting knowledge could even be privatized and
marketed. But what to do with the scientists that do not bring in dollars? The ones that
are not necessarily oriented towards the solution of your problems? The ones that ask
curiosity-driven questions? Their keywords seem somehow opposite to the priorities in
any kind of industry.
Let us assume that you take the plunge and allow them to become a part of your herds.
You may not be able to predict or to influence which direction their research will turn
into, but to fill in some blanks, we will give you just one potential story. We will give you
an overview of about seven years of research carried out at the Ferme des Bisons near
Bastogne.
Back to the farm
In 1991, d’Hoffschmidt bought 240 animals in the USA and kept them in five herds of
30-50 females on large meadows (about 2.5 acres per animal). From June till September
several males accompany the females, usually one adult bull and one or more younger
males. The calves are weaned at around 7 months at the end of the year. The female
calves are sold as breeding stock and the males are either selected as breeding males or
kept in a bachelor herd to be slaughtered when they are around 24 months old. The
animals are habituated to the occasional presence of 4x4 vehicles and a half-yearly
roundup for ear-tagging and deworming allows for the collection of blood, weights and
other data. It is the ideal set-up for research.
The studies
The aim was to conduct two major behavioral studies on sexual competition in bison over
several years and to maximize collaborative side-projects. Catherine Roden studied the
bulls as part of her PhD. She specifically wanted to know whether young competing bulls
managed to father any offspring in the herds at all and how much energy the bulls
invested in reproduction. With regard to the females, I questioned in a postdoctoral
study whether dominance paid off in terms of reproduction. In other words, did high
ranking females perform better? These questions made us answer a string of other
questions: Is there a nice and linear hierarchy among the females? What dominance
style is there in the herd? How exactly do the estrous cycles start? How synchronized are
they at the peak of the mating period? How stressed are the females? Which males do
they prefer? Who gets the preferred male? In what follows, I will elaborate just a bit on
some results. I will give you some more information during the conference presentation.
Female sexual competition
Dale Lott was the world leading authority in American bison behavior. When I obtained
his book on bison behavior and ecology, I was curious to see what he thought about my
topic of interest: female dominance relationships and their pay-offs. He writes: "Bulls
have to compete for mates, cows do not. Cows need grass to eat, water to drink,
companions as a buffer against predators. After the thundering battles of the bulls, the
conflicts of cows seem mellow and understated. Even when they're getting serious, cows’
clashes seem more comic than cosmic." In short, in bison society, cows are not only
rather inconspicuous, but in addition they are not very much involved in competition,
either. At least not in competition for sex. But then, why would they bother about being
dominant? It is acknowledged that bison females periodically need to compete for food.
On the Great Plains, grass can become a scarce commodity. Rutberg already found that
dominant cows need to search significantly less for food and harvest more than
subordinates. For example, when they shove snow aside to feed, dominant females have
enough time to eat all the grass in the crater they made, whereas low ranking
individuals are driven off by other higher ranking animals. He also looked for
reproductive benefits coming to dominant animals. But he found that dominant cows do
not have more calves than subordinate cows.
Is that it? Does their dominance only play a role in relation to food? We took another look
at this question. Determining female dominance relationships among a group of bison
requires fairly long observation periods and good individual recognition. Every
aggression, threat or displacement in which one animal yields to another, must be
scored. We managed to fit every female into a significantly linear hierarchy. After that
exercise, the analysis showed that high ranking females weighed more, molted faster
and were in better condition. Fatness ended up as the most robust factor in the analysis.
Given a similar weight and age, large but thin females are likely to be lower ranking
than small fat individuals.
Bison evolved as a species of prey, especially for wolves, and typically profit from the
dilution effect of numbers. This may explain the relatively tight birth season. Also,
calves need to grow big enough to survive winter and benefit from the springtime
superabundance of high quality forage. Hence, most bison calves are born in May. They
are pressed to grow fast enough, big enough and fat enough to survive predation and to
survive the winter cold. In other prey species, early births have been related to better
survival chances. In bison early births were related to size and faster maturation.
Females that mature early show increased fertility in their further course of life. Can
high ranking females guarantee early births? This was indeed the case. As in the
previous study we did not find that high ranking mothers had more offspring looking
over a period of seven years. Further, the daughters were not fatter or did not have more
calves. One result however strongly stuck out: high ranking mothers had significantly
fatter sons at 18 months, even when controlling for birth dates. A top mother can make a
top son. Male bison must compete fiercely to father the offspring in a herd. A proper
weight may give them a head-start, enabling them to become the jackpot winner.
A string of other questions
To find out whether the top females also had sexual privileges, we closely monitored a
subsample of 13 females in a herd of 42 and collected regular faucal samples and
behavioral data to obtain information on their estrus cycles, ovulation, conception and
throughout gestation. High, mid and low ranking females were chosen at random. We
found out how the hormonal cycles start in the breeding season (like diesel engines, it
turns out). We discovered the best indication of a recent copulation. We calculated how
tightly estrus synchronized estrus was at the peak of the rut and what this meant for
the access to the males. We also looked at the relationship between hormonal stress
levels and whether one would rather be a top, mid or low ranking bison. We found out
that the place where they move in the herd can be predicted by rank. Even their parasite
load was related to their rank.
In conclusion, we found that rank is a powerful predictor not only of bison behavior but
also of the quality of females and their offspring. On every ranch, you will find a
percentage of animals that tends to perform less well than others. Even so, they are
treated the same way as the others; they eat the same food and live in the same herd. No
veterinary can explain this variation in condition and performance, but maybe you can.
Dominance rank might be a golden key to understanding the variation in the quality of
life of your animals.
The side-issues
As side-issues we recorded and played back calf calls to check the reaction of the rightful
mothers. We tested bull roaring for infrasound. We checked whether females recognized
estrus urine from other urine. Other projects in which we collaborated ranged from the
ancestry of bison relatives to pregnancy markers in bison placenta. In addition, we
looked at the genetic ancestral origins of the herd to look for possible Bos taurus hybrids.
When science meets industry
Allowing researchers access to your herds, literally means the presence of people (albeit
in jeeps) in your herds and often during roundups. Roundups may take more time to
allow for additional blood sampling or weighing or the like. All this is balanced by small
and subtle benefits. When scientists publish their findings, it could attract public
attention and put your ranch in the spotlight. Television and radio love bison and they
know where to find the scientists for the occasional documentary or interview.
Involvement in scientific research adds a certain degree of seriousness and
professionalism to your endeavor, which is usually appreciated by governments. You
may climb some steps in the invisible classification of good and bad ranches. And at least
you serve a public good by promoting knowledge and future education. You can at least
make sure that the taxes you invested in that public good come back to you in some way.
You will definitely be able to increase your knowledge of the herd. Maybe this will allow
you to explain a certain degree of variation in the performance of individuals and to
make correct predictions. And maybe you can make better decisions with regard to herd
management. The stories of the lives of your animals will add some zest to bison
keeping. Curiosity, fine tuning and passion are attributes that take us into the realm of
art. When science meets industry, industry becomes art.
Acknowledgements
We would like to thank the following persons for their information on recent numbers of
American bison on commercial ranches and in zoos: Collin Seaford (UK), Hans Jurgen
Schröder (Germany), Niels Ove (Danmark), David Saulie (France), Benoist Piednoir
(INRA-France), Laurent Girardet (Switzerland), Christine Caudron (Belgium), Jeroen
Stevens (Zoo Antwerp). We thank Geert Van den Broeck for all support.
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