History of canids in Chile and impacts on prey adaptations
Benjamín Silva Rochefort1 & Meredith
Root-Bernstein2,3,4
- Facultad de Ciencias Biológicas, Universidad Católica de Chile,
Santiago, Chile
- Center of Applied Ecology and Sustainability, Santiago, Chile
- Institute of Ecology and Biodiversity, Santiago, Chile
- UMR CESCO, CNRS, Musée National d’Histoire Naturelle, Paris, France
Abstract
Artiodactyl prey species of Chile, especially guanacos (Lama
guanicoe ) are reported to be very susceptible to predation by pack
hunting feral dogs. It has been previously suggested that guanacos and
endemic South American deer may have evolved in the absence of
pack-hunting cursorial predators. However, the paleoecology of canid
presence in southern South America and Chile is unclear. Here, we review
the literature on South American and Chilean canids, their
distributions, ecologies and hunting behaviour. We consider both wild
and domestic canids, including Canis familiaris breeds. We
establish two known antipredator defense behaviours of guanacos:
predator inspection of ambush predators, e.g. Puma concolor , and
rushing at and kicking smaller cursorial predators, e.g. Lycalopex
culpaeus . We propose that since the late Pleistocene extinction of
hypercarnivorous group-hunting canids east of the Andes, there were no
native species creating group-hunting predation pressures on guanacos.
Endemic deer of Chile may have never experienced group hunting selection
pressure from native predators. Even hunting dogs (or other canids) used
by indigenous groups in the far north and extreme south of Chile (and
presumably the center as well) appear to have been used primarily within
ambush hunting strategies. This may account for the susceptibility of
guanacos and other prey species to feral dog attacks. We detail seven
separate hypotheses that require further investigation in order to
assess how best to respond to the threat posed by feral dogs to the
conservation of native deer and camelids in Chile and other parts of
South America.
Keywords: anti-predator defense; prehispanic dogs; cursorial; ambush;
hunting; ethnography; evolution of prey behavior; predation strategy
Introduction
The damage to biodiversity caused by feral dogs (Canis familiaris) is well-established globally. Young et al. (2011), in a global review of
feral dog impacts, show that the negative effects of C.
familiaris on native species is widespread. Feral dogs are a serious
problem for conservation, mainly because of their predation on native
species, transmission of diseases, and competition with other predators,
which may destabilize ecosystems (Ritchie et al. 2014; Hughes &
Macdonald 2013). For example, on the Galapagos Islands a significant
decline in marine iguanas (Amblyrhinchus cristatus) resulted from
the establishment of dogs on the island (Kruuk & Snell 1981). Feral and
freely ranging dogs in Brazilian protected areas displace native
predators, spread diseases, and predate small and medium sized wildlife
(Lessa et al. 2016). South America is a hotspot of C. familiaris negative impacts on threatened species (Doherty et al. 2017). Why
exactly are dogs such a destabilizing conservation threat in South
America in particular? Geist (1998) partly addressed one angle of this
question when he concluded that the South American deer are not adapted
to cursorial predators like dogs, and that deer traits like body size,
locomotion, and reproductive investment, imply that there must have been
only ambush predators present during the radiation of the South American
deer species. In this paper, we re-examine and extend this hypothesis,
to ask whether it can explain why deer and also camelids of South
America are so vulnerable to feral dogs. We look more completely at all
the evidence for the hunting strategies of prehistoric predators as well
as domesticated canids associated with Precolumbian human presence. We
focus on the case of Chile, and we end our review by evaluating the
state of knowledge and suggesting hypotheses that need to be researched
in order to better understand how the evolution and ecology of
predator-prey interactions affect possible responses to the conservation
challenge posed by feral dogs.
In Chile, feral dogs represent economic as well as environmental damage. C. familiaris is estimated to cause 57,000 sheep deaths annually
(Bonacic & Muñoz 2014), although it should be noted that this includes
deaths caused by both feral and domestic dogs allowed to freely roam
agricultural areas. Both feral and freely ranging human-dependent dogs
cause significant reductions in the populations of threatened species in
Chile. Freely ranging dogs that are poorly fed are more likely to prey
on and harass wildlife (Silva-Rodríguez & Sieving 2011). Rural dogs are
interference competitors with the native fox Lycalopex griseus (Silva-Rodríguez et al. 2010), eat the eggs of migratory birds that nest
in Chile (Shuttler et al. 2009), and predate on native deer species,
including pudu Pudu puda (Silva-Rodríguez et al. 2009;
Silva-Rodríguez & Sieving 2012), and huemul Hippocamelus
bisulcus (Flueck & Smith-Flueck 2006; Corti et al. 2010). Reports from
Peru (Barrio 2007) state that fawns of taruka, Hippocamelus
antisensis, a deer also found in northern Chile, may be killed by
shepherd and feral dogs. The native camelids, principally guanaco
(Lama guanicoe), are considered by experts (pers. comm. WCS
Chile Grupo Núcleo Guanacos 2020) to be particularly susceptible to
being killed by feral dogs, and dog presence is considered to be a
factor preventing the conservation and reintroduction of Lama
guanicoe in large parts of its historical range (Farías et al. 2010;
González 2010). According to McLaren et al. (2018), vicuña
(Vicugna vicugna ), a high-altitude relative of the guanaco, are
hunted and harassed by humans with dogs, but feral dogs primarily
predate on young offspring. It should be noted that the extent of the
threat to species posed by dogs in Chile is partly due to the lack of a
legal or cultural basis for their control, lethal or otherwise.
However, there are also behavioural and evolutionary features of
predators to consider when trying to understand why feral dogs present a
large and difficult-to-control threat to Chilean wildlife. When
understanding predation, there are two key factors to consider: the
predator’s niche, and its hunting strategy. In terms of their niches, in
general most canids (Carnivora: Canidae) are omnivores that do not kill
(but may scavenge) prey larger than themselves (Sheldon 1992). Small
canids < 6 kg are solitary foragers, canids 6-13 kg are
facultative cooperative foragers, and larger ones are obligate
cooperative foragers (Sheldon 1992) likely to be specialized as
carnivores, with some exceptions (Wang et a. 2004). Canids, like other
predators, may use either cursorial (pursuit) or ambush strategies. In
cursorial strategies, the predator relies on its running adaptations and
stamina to exhaust the prey, and may lack specific killing tactics,
rather relying on bringing the prey down by biting (Fox 1987; Sheldon
1992; González 2010). In ambush strategies, the predator stalks the
prey, remaining undetected until it can pounce on or rush at the prey
from a short distance; it may rely on specialized killing tactics (Fox
1987; Sheldon 1992). For example, puma (Puma concolor ) are ambush
predators that kill with a specialized crushing bite to the head (Sarno
et al. 1999).
In turn, prey species have adaptations such as scanning for predators,
alarm calls, escape tactics, group defence tactics, and so on, which may
be suited for different predator body sizes, group sizes, and either
pursuit or ambush predation strategies (see Caro et al. 2004).
Essentially, to escape cursorial predators, prey need to outrun or lose
them. By contrast, the advantage of ambush predators is their ability to
take a targeted prey individual by surprise from a short distance. An
effective defence against ambush predation is “predator inspection”
which consists of staring at, approaching, surrounding and/or following
the predator so that it cannot gain this advantage (FitzGibbon 1994
provides an excellent review). In a study of gazelle, FitzGibbon (1994)
found that they were much more likely to inspect ambush than cursorial
predators. Inspecting cursorial predators is likely to be risky and
maladaptive, as by shortening the distance to the predator it may
increase the chances of being overtaken.
In its feral state, C. familiaris hunts in packs using a
cursorial strategy (Farías et al. 2010; Ritchie et al. 2014). Geist
(1998) notes that all of the South American deer lack appropriate
defenses against what he calls “culling” predators, by which he
appears to mean a cursorial strategy where one or more predators picks
out and runs down its prey. Geist notes that South American deer are
“curious” which suggests they approach possible threats. They also
respond too late to attacks, are saltatorial bounders rather than
runners, and lack stamina (Geist 1998). It has also been suggested that
guanaco lack adaptations to escape cursorial pack hunters
(Root-Bernstein & Svenning 2016). The guanaco demonstrates group
vigilance and predator inspection, suitable for countering its main
native predator, the puma (P. concolor), which hunts by solitary
ambush (Darwin 2015 [1839]; Marino & Baldi 2008; pers. obs. MR-B). It
is not entirely clear whether guanacos inspect dog packs, but González
(2010) attributes high dog-caused mortality to guanacos’ short bursts of
fast flight, leaving them unable to outrun dogs with greater stamina.
Oyama (2006) describes vicuña (V. vicugna ) in the Peruvian Andes
as approaching possible threats such as dogs, and facing predators while
giving an alarm call. Similarly to the case of guanaco, vicuñas’ main
predators, including puma and foxes, hide in the long grass and ambush
them.
If South American deer and camelids lack appropriate defense behaviours,
does this imply that this is an evolutionary problem—that they lack an
adaptive trait? Although prey must respond differently and appropriately
to different predators, this does not necessarily imply the evolution of
completely independent responses to each predator. Lind and Cresswell
(2005) make the valuable point that “antipredation behaviours are a
composite of many behaviours that an animal can adjust…” (p. 945).
Components of anti-predator behaviour can be lost under loss of
predation pressure, but the presence of any kind of predator may be
enough to retain a whole suite of antipredation behaviours for tens of
thousands of years (Blumstein 2006). So, to assess the hypothesis that
key native Chilean prey species—camelids and deer—lack evolutionary
adaptations to cursorial group predation, we would need to establish
that they never in the past experienced selection pressures in the form
of cursorial group hunting predators. Thus we need to understand when
cursorial group-hunting canids first appeared in the southern cone of
South America, which is not entirely clear. We focus on canids simply
because there are not, and have never been, any group-hunting or
cursorial felids in South America.
It is clear that European conquistadors brought domestic dogs to the
Americas starting around 500 years ago. However, the history of canids
in South America, and ecological and behavioural descriptions of any
kinds of prehispanic South American canids, have not been synthesized in
a way accessible to conservationists. Here, we review existing evidence
for the presence of prehispanic canids and their behaviours and
ecological roles, focusing on Chile and the southern cone of South
America.
Canids and their hunting ecology