Vocal communication between cows and calves in
extensive range conditions
University of Saskatchewan
Large Animal Clinical Sciences
Western College of Veterinary
Medicine
J. M. Watts, J. G. Hall, J. M. Stookey, M. R. Arndt and B. Valentine
Jon M. Watts
Saskatoon, Saskatchewan, CANADA
Introduction
The mother-offspring bond in cattle is characterised by emotional,
social, nutritional and physiological interdependence. The vocal
behaviour of the cow and calf is an important factor in the formation
and maintenance of this bond. Despite the dependence of the calf
on its mother, the cow and calf are not inseparable. In fact, they will
be spatially separated and performing activities independently at
certain times from the earliest days of the calf’s life. In order to
reunite, a separated cow and calf will need to search for, locate and
ultimately recognise each other. At close range cattle may identify
each other by sight. In extensive pastures cows and calves will often
be unable to see each other. Vocal communication is one strategy
available to cow-calf pairs when attempting to locate or regain
contact with each other under such conditions. This study
investigated the role of vocal behaviour in maintaining and regaining
social contact between cows and their calves in an extensive, mixed
terrain environment.
Figures 3 and 4. A common separation scenario: calf lies down while cow moves away grazing.
Results
In 456 h of focal observation, 44 cow-calf pairs were followed from one nursing
to the next. The average interval between nursings was 299 " 16 min. During
19 observing sessions cow and calf became separated to the extent of
appearing to be out of visual contact with each other at least once. The mean
duration of separations was 41.35 " 8.42 min, with a minimum of zero
minutes (momentary separation) and a maximum of 176 min. The most
common scenarios leading to separation were either that the cow moved away
grazing while the calf lay down (11 of 19 pairs), or that both animals were
standing and active and became separated while grazing or otherwise moving
independently. The proportion of time spent separated was negatively
correlated with calf age (Spearman; r=-0.57; N=19; P<0.02).
450
Materials and Methods
Animals and study area
The study was carried out at a community pasture approximately 50
km south of Saskatoon, Saskatchewan at 51o40' N, 107o15' W.
Crossbred cow-calf pairs, (N=209) from 7 local farms and 6
Charolais breeding bulls were pastured together. Calves were aged
between 14 and 70 d at the beginning of the study. Male calves had
been castrated prior to their entry into the community pasture
system. All cattle had been branded with the owner=s registered
mark and had numbered ear tags. These together with distinctive
phenotypic features such as colour markings and size were used to
identify them in the field. At the start of the study the animals were
introduced into 777 ha of native pasture, and were moved 21 d later
to 510 ha of native and crested wheat grass pasture. Both areas
consisted of undulating, mixed terrain, with open grazing areas,
small sand dunes and stands of trees. Water was available in
troughs filled by wind driven pumps and sloughs.
Figure 2. The end of a
suckling episode signalled
The start of the focal
observation interval.
Observing methods
In each observing session a focal cow and calf pair was watched
from one suckling period to the next. Observations were made from
horseback, or while leading a horse, by two observers one of whom
watched the cow while the other watched the calf. Activities of the
focal animals were continuously recorded as well as the time that
they occurred. If the cow and calf became separated each observer
followed his or her focal animal and maintained contact with the
other by radio.
Time between nursings (min)
Figure 1. Herd resting in extensive study area.
Neither vocalised
400
Cow only vocalised
Calf only vocalised
350
Both vocalised
300
250
200
150
100
50
0
Figure 5. Mean " S.E. of nursing intervals compared by which
members of the pair vocalised. (P=0.0625).
During the 44 cow-calf pair observations 20 cows and 26 calves vocalised at
least once. As the time between nursings increased so did the probability that
one or both members of a pair would vocalise (See Figure 5). The numbers of
vocalisations given by individual cows and their own calves were highly
correlated (Spearman; r=0.605; P<0.001).
Searches during which the cow vocalised averaged 69.0 " 15.13 min
compared with 14.4 " 6.05 min when the cow was silent (Mann-Whitney;
U=48; N1=5; N2=11; P<0.05). Calves that vocalised at shorter intervals while
searching achieved shorter search times (Spearman; r=0.56; N=19; P<0.02).
The average interval between coming back within visual range and actually
starting to nurse was 63.6 " 16.6 min.
Conclusion
The relationship between vocal activity of cows and their own calves suggests
they are communicating specifically with each other. The link between vocal
activity and search times indicates that vocalisation is involved in locating
each other in an extensive environment. Vocalisation may serve to limit the
duration of excessively long periods of separation. However given the long
intervals between regaining contact and nursing, the vocalisations do not
appear to be signalling an immediate need to nurse.
Acknowledgements
This study was supported by the
Saskatchewan Agriculture Development
Fund. Thanks are due to the Prairie Farm
Rehabilitation Administration, Peter Gonnet
and Steve Beck.
Figure 6. Together again! – a cow and
calf reunited.