Influence of moon phase on temporal activity & predator-prey
overlap
It is recognized that the response of nocturnal mammals to moonlight
differs among taxa and may vary according to several determining
factors, such as phylogeny, trophic level, sensory systems and human
activity (Santos et al., 2019). This camera-trap based assessment has
revealed both lunar phobic and lunar philic behaviors of rare and/or shy
animals and contributes to building our understanding of the factors
shaping activity patterns of multiple sympatric mammals under different
lunar phases.
Our results indicated that leopards show no activity pattern throughout
the four lunar phases, exhibiting neither a clear lunar phobic nor lunar
philic activity pattern, as observed in other felid species too, such as
puma (Puma concolor ) and jaguar (Panthera onca ) in
Neotropical forests (Harmsen et al., 2011, Prugh and Golden, 2014). Due
to the extraordinary reflectance of the feline tapetum cellulosum,
assessed to reflect 130 times extra light than the human eye (Huck et
al., 2017), we suspect that the leopards’ lack of tendency to be more or
less active during the full moon can be at least partly explained by
visual acuity. We also suppose that the leopards’ irregular temporal
patterns may be influenced by mesopredators in the landscape, such as
red fox (Vulpes vulpes ) and leopard cat (Prionailurus
bengalensis ), as sympatric carnivores can drive temporal activity
fluctuations (Packer et al., 2011, Hua et al., 2020). In terms of human
activities, human-leopard conflict has been found to occur often in the
summer in TPNR (Hua et al., 2020), and perhaps this can explain
irregular activity patterns and the higher relative species abundance in
winter. Human activity on foot and in vehicles mostly occurred in the
day time in TPNR, so a landscape of fear induced by human activities may
adjust leopard behavior, for example our earlier research work conducted
by Hua et al., (2020) In TPNR concluded that grazing intensity by free
roaming cattle was lower in the winter than summer and may also
influence wild animal behavior.
For the herbivore prey species studied, our results are similar with
previous research showing that mammals often adapt their nocturnal
activity to the level of lunar illumination (e.g (Huck et al., 2017,
Pratas‐Santiago et al., 2017). Here, wild boar and Tolai hare were
evidently lunar phobic, while roe deer indicated lunar philic activity.
Especially in the case of the wild boar and Tolai hare, the results
align with the visual acuity hypothesis, as lagomorphs and suids have
poor eye sight and avoid the brightness of moon to reduce predation risk
(Pratas‐Santiago et al., 2017, Preisser et al., 2005, Tuan, 1979, Zaman
et al., 2020a). Lunar phobic behavior has also been observed in
Neotropical prey species, such as armadillo (Dasypus
novemcinctus ) and paca (Cuniculus paca ) (Harmsen et al., 2011,
Prugh and Golden, 2014), while hare have also been observed to dodge the
risk of predation by medium-sized felids by adjusting temporal activity
(Griffin et al., 2005). Deer species however, including white-tailed
deer (Odocoileus virginianus ) and red brocket deer (Masama
temama ), have shown both lunar phobic and lunar philic behaviours, and
while they have tapetum, prey can shift their night activity because the
choroidal tapetum fibrosum (CTC) of carnivores has better light
reflectance than the choroidal tapetum fibrosum (CTF) of ungulate
herbivores (Botts et al., 2020, Brown et al., 1999).
Although felid activity patterns rarely relate with those of their
potential prey (Ramesh et al., 2012) (Krittika and Yadav, 2020), in this
study, leopard nocturnal activity had high overlap with that of roe deer
and Tolai hare across the full lunar cycle. These results support the
prediction that predators should reduce activity at times when major
prey species are less active, in accordance with both the visual acuity
and optimal foraging model (Pianka, 1973, MacArthur and Pianka, 1966).
Conversely, prey can adjust their activity pattern or spatial
distribution to avoid predators (i.e., to reduce predation risk), such
as bighorn sheep (Ovis canadensis ) spatially eluding pumas
(Puma concolor ) (Laundré et al., 2001), and roe deer and wild
boar having minimal temporal overlap with tigers (Yang et al., 2019).
Hence, while lunar phobia (wild boar and Tolai hare) and lunar philia
(roe deer) were observed in the prey species in this study, the activity
pattern of leopards observed here, we suspect, is more closely linked
with the temporal behaviors of prey species than directly with moon
phase per se .
Explicitly during the full moon phase, nocturnal activity of leopards
and prey were diversely affected by clear summer nights and moon risk
index (MRI). Leopards activity during the full moon showed preference
for high lunar luminosity (high MRI) and showed higher activity during
clear summer or winter nights. We suppose that clear summer or winter
nights or active prey may either force leopards to restrict roaming
behavior (and reduce hunting success) or may increase activity as they
move towards a safe or warmer refuge (Türk and Arnold, 1988). For prey
species, nocturnal activity events during the full moon were more for
roe deer in summer or winter (seasonal effect), during clear bright
nights for wild boar (clear cover and MRI interaction effect), and
during clear nights (especially summer ) for Tolai hare (clear cover and
MRI interaction effects). Others have also revealed that cloud cover,
which alters moonlight and MRI (Packer et al., 2011, Pratas‐Santiago et
al., 2017) and season influence nocturnality and temporal behaviours of
carnivores and ungulates (Shamoon et al., 2018), as well as foraging
behaviour of wild boar and roe deer (Frauendorf et al., 2016, Yang et
al., 2018a).it is reasonable to assume that there is variation in
nocturnal activity between seasons.