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- The
information in this section is provided by
Brigit Dörges and Jürgen Heucke. This
information is a result of many years of
scientific research carried out on Newhaven
Station in Central Australia.
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- The
most distinctive behaviour of the adult bull is
determined by the rut. The rut lasts six months
on average and with the majority of bulls occurs
between April and September. In the research
paddock 15 adult bulls were observed. Below
shows summarised seasonal distribution of
nutting behaviour.
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- Externally
the rut can more or less be seen by the
secretion of the occipital glands, often by a
swelling of the testicles, but always by the
typical behaviour. Rutting behaviour is only
shown when cows are present. Usually it occurs
at the age of 4-5 years. In individual cases it
can take place from the age of three
up.
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- The
rutting periods of the adult bulls last between
a few weeks up to 7 months and occur in
irregular intervals of 3-17 months.
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- The
duration of the rut depends on internal and
external factors. The constitution and the
hormonal condition of the bull are apparently
decisive but also his self assertion towards
competitors. At the beginning of the main
breeding season in winter more or less all adult
bulls are in rut. The strongest ones then take
over a cow group and defend it against rivals.
The remaining bulls try to compete for the cows
but in 94.5% of all cases are being chased away
by the group-holder and either migrate or stay
at the periphery of the group.
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- Depending
on his constitution the group-holder herds the
cows for 3-5 months, but he can be replaced by a
competitor before that.
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- Some
bulls that do not have a chance to take over a
cow group during the main breeding season come
into a second rut in spring or in summer.
Because of the lack of competitors they then
succeed in herding a cow group. In some cases
these bulls even succeed in reproduction. Mostly
the bulls stay in bachelor groups or solitarily
in summer, even though there are contacts or
even short-term associations with
cows.
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Bull groups occur throughout the year and
consist of a changing number of adult and/or
subadult bulls.-
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Older buIls live more solitarily.
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Outside the main reproduction time, in summer,
the cows live in cow groups without an adult
bull. These groups consist of adult cows with
their young, other adult cows, and male and
female subadults.
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At the beginning of the breeding season in
winter (April to May) almost all adult bulls are
in rut. The cow groups are taken over by a bull
who then herds them for three to five
months.
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After taking over a group, the herding bull
chases away all subadult bulls who then join
bachelor groups. However, he tolerates the young
cows who remain in their mothers'
group.
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Before parturition the pregnant cow leaves the
group and gives birth in a remote area. She then
lives alone with the calf for up to three
weeks.
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Mothers with young calves join together, forming
the basis of a new cow group (core
group).
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Toward the end of winter the herding bull loses
interest in the cows and leaves them
voluntarily. He then lives solitarily or joins
other bachelors.
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Weaker adult and above all young bulls who did
not have the chance to take over a cow group
during the main breeding season come into rut a
second time in summer or in autumn. They then
also herd cow groups but are driven away by
dominant bulls at the beginning of the winter at
the latest.
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- Legend
- 1.
bull group
- I
a. older bulls may live solitarily
- 2.
cow group
- 3.
bull joins cow group
- 4.
bull herds cow group
- 5.
dominant bull expels subad. males, these join
bachelor groups
- 6.
pregnant cow segregates before
parturition
- 7.
cows with young calves form new core
group
- 8.
bulls leave cow group voluntarily
- 9.
younger or weaker bulls herd cow group
temporarily
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- Size
of symbols corresponds to respective age
class.
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