Elevated potential for intraspecific competition in territorial carnivores occupying fragmented landscapes

Abstract

The distribution of mammals is determined by a suite of endogenous and exogenous factors. In territorial, polygynous species, like tigers (Panthera tigris), males endeavour to center their space-use around female territories, repelling competitors from these areas. Competition among males for females leads to increased mortality of both sexes and infanticide of unrelated cubs, which can lead to population declines. We hypothesized that increased territorial overlap among adult male tigers and elevated levels of inter and intra-sex competition would be manifest in populations with male-biased adult sex ratios (ASR). We also assessed whether inter-sex variation in adult survival or degree of habitat connectivity resulted in skewed ASR. We evaluated these hypotheses using camera trap data from three tiger populations occupying habitat patches with varying levels of connectivity and ASRs. Data were analyzed using multi-state occupancy models, where states were defined as habitat use by one or more male tigers, in sites with and without female use. As predicted, in populations with male-biased or even ASR, we found evidence for increased spatial overlap between male tigers, particularly around female territories. Given parity in adult survival, habitat fragmentation likely caused male-biased ASR. Our results suggest that the persistence of small tiger populations in habitat patches with malebiased ASR may be especially influenced by behaviour-mediated endogenous demographic processes that are often overlooked by managers. In habitat fragments with severely skewed ASR, population recovery of territorial carnivores may require timely supplementation of individuals to compensate for population losses from intra-specific competition.

Optimal foraging of lions at the human wildlands interface

“…More general avoidance of human‐dominated habitats has been documented with cougars Puma concolor , (Blecha et al, 2018), grizzly bears Ursus arctos (Ordiz et al, 2011) and Sri Lankan leopards, Panthera pardus kotiya (Kittle et al, 2021). A species' ability to negotiate a fear landscape may be dependant on co‐evolution with competitively dominant sympatric species, such that it recognises the potential fitness consequences of certain interactions and avoids threatening situations (Chanchani et al, 2018). In spite of their trophic position, many apex predators belong to diverse predator communities and are vulnerable to intra‐guild predation, particularly at younger, more vulnerable life stages or other forms of interference competition.…”

Rapid defaunation of terrestrial mammals in a protected Neotropical cloud forest remnant

“…However, anthropogenically mediated declines overriding such (natural) variation have been demonstrated elsewhere (Toews, Juanes, & Burton, 2018), in some cases enhancing the drivers of such variation (Chanchani, Gerber, & Noon, 2018). The potential impacts of such anthropogenic effects is variable but may lead to extinction of local populations (WWF, 2018), entire species (Ripple et al, 2019;Ceballos et al, 2015) and alteration of community structure (Hagen et al, 2012).…”

Impacts of hydropower on the habitat of jaguars and tigers

“…Given evidence on animals rescued from flooded areas and released in habitat surrounding the reservoir (see ref. 43 for a recent review), here we assumed that the predators would not be likely to survive the habitat loss resulting from reservoir flooding; even if displaced to surrounding intact habitats, the available prey base, habitat area, and potential resulting competition would likely cause higher mortality and thereby maintain the estimated densities 56 , 57 . While this study aims to illustrate and compare the different scenarios for jaguars and tigers under existing and future hydropower development, we acknowledge that these are rough estimates that were not based on in situ studies of the response of these species to habitat flooding, which are currently unavailable.…”