deterrent effect can provide real benefits, although it might
be undesirable if an endangered species is involved. Livestock
guardian dogs can be used to limit herbivores’ access to
grazing areas, allowing pastoralists to better regulate the total
grazing pressure in different paddocks. Their presence can also
help primary producers with early stage re-vegetating or even
re-wildling projects, preventing grazers from browsing newly
planted saplings. The presence of guardian dogs can also reduce
transmission of diseases from wildlife to livestock. Bovine
tuberculosis and Johnes disease are both transmitted between
deer and livestock; segregating the two can help limit the spread
of these contagions.
No trespassing
A third way that guardian dogs can affect wildlife is less direct.
Controlling populations of predators might offer some protection
for wild species – particularly birds, reptiles and small mammals
that are preyed upon by smaller carnivores. When it comes
to chasing away predators, guardian dogs are not picky: all
predators are treated as a threat. Smaller predators such as red
foxes and feral cats are seen off with the same diligence as larger
predators such as feral dogs. My camera survey suggested that
foxes use an area differently when guardian dogs are present.
Foxes were less likely to occur in the core of the patrolled
range than at the edges, and, like kangaroos, showed a strong
temporal avoidance of guardian dogs; that is, they usually only
showed up in areas the dogs hadn’t visited for days. Although
they still occasionally accessed the sheep paddocks, they did not
attack any lambs. Most likely, this resulted from a change in fox
behaviour, one that my study was not designed to detect. When
a fox enters a guardian dog area, it is probably very aware it is
trespassing on dangerous ground. It is likely to be more alert and
cautious, hurrying through without taking time to hunt. In the
United States, a study found that the presence of guardian dogs
in an area limited the access of raccoons, opossums, skunks and
foxes when compared to a similar area without guardian dogs.
Researchers also found an increased number of ground-nesting
bird nests in areas with guardian dogs, and less predation on
these nests. Ground-nesting birds and their eggs are prey for the
aforementioned four predators. It seems likely that limiting the
access of those predators to guardian dog areas increased the
nesting success.
Fear factor
Here in Australia, predation by foxes and feral cats is thought to
be one of the factors driving the decline and extinction of many
small native mammal, bird and reptile species. By influencing
the predatory behaviour of foxes and cats, guardian dogs might
create refuges for species vulnerable to fox and cat predation.
Their role in the environment can be considered similar to
the ecological role wild top predators, such as dingoes or
wolves, play within their environment. Apex predators alter the
distribution and behaviour of both smaller predators and wild
herbivore species.
Fear is a powerful motivator. Nervous prey will try to avoid
encountering a predatory species by avoiding high-risk areas,
or at least by reducing the amount of time they are exposed
to potential attack. If large herbivores change their behaviour
and keep away, this might lead to a reduction of grazing on
surrounding plant communities, favouring small herbivorous
species by removing competition from larger grazers. At the
same time, smaller predators, also fearful of encountering
the apex predator, will avoid high-risk areas or reduce their
time there, decreasing the predation pressure on those
small herbivore species. When a top predator is removed by
culling, or containment (such as fences), flow-on ecological
changes known as ‘top-down trophic cascades’ can result and
can upset ecosystems, providing advantages to species that
might otherwise have been controlled by predation. Although
guardian dogs don’t prey on other animals in the way a dingo
or Tasmanian devil would, they appear to have a similar fear-
inducing impact on the distribution and behaviour of large
herbivore and small carnivore species, resulting in similar
ecological benefits.
When I first drove up that mountain to study white dogs in the
snow, I didn’t know much about any of these benefits. The dogs
sniffed me, checked me over and, once satisfied I was no threat,
escorted me into the sheep paddock, where they settled down with
their flock. I remember thinking they were doing a pretty courageous
and amazing job. What I didn’t realise then was just how much more
the task entailed than simply looking after sheep.READING Gehring T, Vercauteren K, Landry J. 2010. Livestock protection dogs in the
21st century: Is an ancient tool relevant to modern conservation challenges? BioScience
60 (4): 299–30 van Bommel L, Johnson CN. 2012. Good dog! Using livestock
guardian dogs to protect livestock from predators in Australia’s extensive grazing
systems, Wildlife Research 39 (3): 220–9 Ripple WJ, et al. 2014. Status and ecological
effects of the world’s largest carnivores, Science 343 (6167), 1241484 van Bommel L,
Johnson CN. 2016. Livestock guardian dogs as surrogate top predators? How Maremma
sheepdogs affect a wildlife community. Ecology and Evolution 6 (18): 6702–LINDA VAN BOMMEL is a postdoctoral researcher at the University
of Tasmania, studying non-lethal predator management and wildlife
conservation. She did her PhD on the use of livestock guardian dogs in
Australia, after developing an interest in flock guardians while studying
large predators in Africa. She is the author of the Best Practice Manual for
the Use of Livestock Guardian Dogs.In pastoral areas, guardian dogs may be
considered livestock-friendly surrogate top
predators, which, in addition to keeping
livestock safe, benefit the environment by
providing important ecological functions.
Photo: Linda van BommelCONSERVATION INNOVATION
18 | Wildlife Australia | SPRING 2017