DISCUSSION
Although we found a high activity overlap between jaguars and pumas,
such as other studies (Scognamillo et al . 2003; Harmsen et
al . 2009; Harmsen et al . 2011; Foster et al . 2013), their
activity pattern was significantly dissimilar. Corroborating the
findings of Hernández-SaintMartín et al. (2013), we also observed a
negative correlation between the peak of activity of jaguars and the
peak of activity of pumas. Pumas used much more of the daylight compared
to jaguars, especially in EP. This can be characterized as a time
partitioning between these predators, where pumas might be negatively
influenced by having smaller body sizes (Iriarte et al. 1990).
Therefore, as pumas are subordinate to jaguars, they tend to avoid the
peak of the activity of jaguars to reduce the probabilities of IGP and
IK.
However, different temporal activity patterns, such as the case of
jaguars and pumas, may allow each predator to make use of different
preys more efficiently and thus, facilitate coexistence between
competing species. Although we did not sample important prey species for
jaguars, such as capybaras and caimans, this predator overlapped
temporally with eight prey species in our studied area. Contrary, pumas
are temporally overlapped with pacas in RD, with peccaries in EP, and in
both areas with deers. The temporal overlap between the puma activity
and the deer activity is not a surprise as deers are commonly found in
puma’s diet (Scognamillo et al. 2003; Novack et al. 2005; Moreno et al.
2006), and the shift in the activity pattern found for pumas (i.e.,
nocturnal in RD, but cathemeral in EP) might be related to the deer
activity patterns. Red brocket deers prefer forested areas (i.e., RD)
and are nocturnal, whereas gray brocket deers are more generalist and
diurnal (Ferreguetti et al. 2015). Therefore, it is possible that pumas
increase the likelihood of preying on red brockets in RD by using more
of the nighttime and gray brockets in EP by using more of the daytime.
This shift in the activity pattern found for pumas reinforce the high
plasticity of the species to adapt to different environmental conditions
(De Angelo et al. 2011; Moss et al. 2016).
Ocelots with jaguars showed a high and significant temporal overlap in
all areas and in RD with pumas, suggesting that coexistence might be
facilitated by differences in other niche dimensions (Davies et al.
2010) or even facilitated by the low density of jaguars in our study
area (Viana 2006), which might result in few encounters with this
species (Davies et al. 2010). Also, ocelots prey mainly on rodents (Mezaet al . 2002; Moreno et al . 2006; Booth-Binczik et
al . 2014) but can prey on primates (Bianchi and Mendes 2007; Abreuet al . 2008; Bianchi et al . 2010). Importantly, smaller
preys are selected by ocelots when in sympatry with jaguars (Morenoet al . 2006). Therefore, ocelots are probably limited to smaller
preys in our studied areas, which may reduce competition with the larger
felids in this potentially competitive scenario, where ocelots are
clearly a victim of IGP and IK due to its smaller body mass (Oliveira
and Pereira 2014).
Crab-eating-foxes with jaguars, pumas, and ocelots showed a significant
temporal activity overlap, but the species prefers areas with
intermediate forest cover and broader trails (Goulart et al .
2009), which are characteristics found in EP. The crab-eating-fox
activity pattern was dissimilar from pumas in EP, which combined to the
low density of jaguars, may result in low risks of IGP and IK. Also, the
great body mass differences with jaguars and pumas and the low density
of jaguars may result in low risks of IGP and IK. Similarly, the small
body mass difference between crab-eating-foxes and ocelots may reduce
IGP and IK risks. Therefore, because the IGP and IK risk for the
crab-eating-fox are unlikely, the species may benefit greatly for
hunting preys (i.e., tapetis) in EP.
As expected, tayras showed a diurnal activity pattern and, therefore, no
significant overlap was found with the temporal activity pattern of
jaguars, pumas, and ocelots. Although mustelids have one of the highest
competitive pressure among the American carnivore families, tayras are
omnivorous and can use arboreal strata and aquatic environment, which
may facilitate the coexistence with dominant predators (Hunter and Caro
2008).
Coatis with pumas in EP showed a significant temporal activity overlap,
but as coatis are mainly diurnal, have an omnivorous feeding habits, and
frequently uses the arboreal strata, it present low risks of IGP and IK
by pumas. This is somehow expected, given the lowest competition
pressure among the American carnivores of the Procyonidae family,
possibly due to their ability to change the spatial and temporal use of
resources (Hunter and Caro 2008).
Contrary to our initial hypothesis, most predators did not show less
diurnal activity where human activity was higher (i.e., EP). Jaguars and
coatis showed similar temporal activity in RD and EP. The few records of
crab-eating-foxes and tayras did not allow us this comparison, but
crab-eating-foxes only occasionally use RD. Only ocelots were more
nocturnal in EP, but this might be a response to the tapetis activity
pattern, an important and apparently abundant prey that also was more
nocturnal in EP. Of course, this higher nocturnal activity of ocelots in
EP also might result in fewer encounters with both pumas and humans,
which was suggested to be a mechanism (or strategy) adopted by ocelots
to allow its coexistence with pumas and humans in Atlantic Forest
remnants (Massara et al., 2018). Surprisingly, pumas were more diurnal
where the human activity is higher (i.e., EP), contradicting other
studies (Paviolo et al. 2009; Carter et al. 2012; Schuette et al. 2013).
We have two hypotheses to explain this result. Firstly, both study areas
are so isolated and saturated with predators that competition is high
and the benefits of hunting during the daytime outweigh the risks of
encountering humans. Secondly, human activities in EP may not be as
intense as we expected and because the eucalyptus management is limited
mainly to smaller areas at each given time thus, leaving the rest of the
area untouched, the encounters with humans are unlikely.
We observed that temporal partitioning contributes to the coexistence
among predators in our studied areas. Pumas avoided conflicts with
jaguars by using more the daytime, which increased also the likelihood
of encountering diurnal preys, especially in EP. Ocelots avoided
conflicts with pumas in EP by being more nocturnal, but the coexistence
in RD with jaguars must be facilitated by the different use of preys.
Tayras and coatis were diurnal, which might result in a low probability
of agonistic encounters with nocturnal felids, besides the different
niches among them. The temporal partitioning seemed unimportant only for
crab-eating-foxes, but they probably coexist with felids by using the
habitat and preys differently. In other words, our findings suggest that
temporal partitioning contributed to the coexistence of predators by
shifting the temporal activity pattern of the subordinate predator to
hours that the dominant predator is less active, thus reducing the
chances of direct conflicts. The shift in the activity pattern by the
subordinate predator may also contribute to reducing competition by
increasing its chances of encountering different preys.
However, in some cases the temporal partitioning did not occur or it was
very subtle, since it depends on some other factors (or variables), such
as the density of the dominant predators (Durant 1998; Davies et al.
2010), the other niche dimensions (e.g., diet) (Davies et al. 2010), the
prey availability (Carrillo et al. 2009), and the human activities
(Paviolo et al. 2009; Carter et al. 2012; Schuette et al. 2013), which
needs to be investigated by further studies. We suggest that future
studies use a combination of the spatial (e.g., telemetry data),
temporal and trophic (e.g., diet data) dimensions of the niche to
evaluate the drivers that may facilitate species coexistence in the
Atlantic Forest fragments. Also, it is reasonable to expect that species
will respond differently to human activities and matrix type and thus,
these studies should also consider natural patches in different
disturbance scenarios, which may also favor (or not) species dispersal.
These studies are even more urgent for those more specialist species,
such as jaguars, which are more susceptible to extinction in the current
scenario of the Atlantic Forest.