Denning behaviour in a species helps to maximise its overall survival fitness in its habitat by securing a foothold place against adverse climatic conditions and interspecific predation
Hyena is a scavenger, largely dependent on kills made by co-predators to meet its dietary requirements. Photo: iStock. Since life evolved on earth, it has diversified into different forms. Out of these, we have lost more than 99 per cent of life forms that ever existed and now the conservation of remaining species has become a major concern throughout the globe.
Conservation of remaining biodiversity is crucial as each species is directly or indirectly engaged in transferring energy from one form to another, which is essential for our survival.
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The elimination of a single species from an ecosystem can potentially impair this delicate fabric of balance between systems. Throughout the globe, concerned communities are practising and implementing different approaches to conserve our biodiversity.
Despite this, we are losing the population of important species at an unprecedented rate. Now, the question arises as to how this extinction rate can be effectively minimised.
It is impossible until we develop a comprehensive understanding of species ecology, including their evolutionary history and behavioural responses to both biotic and abiotic entities of their habitats.
A striped hyena seen inside a den. Photo: Ashish Kumar
Denning behaviour is one of the important aspects of ecology of many important species. Here, we endeavour to explain the significance of denning behaviour in animal ecology, particularly in response to biotic factors.
It also summarises our study on den site selection by striped hyena published in the journal Tropical Ecology.
Denning behaviour in a species helps to maximise its overall survival fitness in its habitat by securing a foothold place against adverse climatic conditions and interspecific predation by its competing species.
Denning is a central behaviour of the breeding ecology of den-dwelling meso-carnivores like a hyena.
The term meso-carnivores refers to a group of carnivores which are subordinate to large carnivores like tigers or leopards in terms of size.
Currently, meso-carnivores like hyenas, dhole and wolves tightly share their habitat with their super-ordinate large carnivores like tigers and leopards in most of their distribution ranges.
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These sympatric species compete over similar resources to a significant extent, resulting in intra-guild predation of subordinates. It is also a matter of fact that these competing species have evolved with distinct feeding niches potentially to minimise intra-guild competition.
But this evolved segregation is not enough to completely evade the interspecific competition and its extreme aftermaths that is intraguild predation.
This is major because of two reasons. First, despite the niche segregation, some prey species overlap between species. Secondly, most of these meso-carnivores often exhibit the behaviour of kleptoparasitism (larger and dominant carnivores stealing the kills from smaller carnivores).
These two reasons often bring them into a state of conflict. Dens act as a competition refugia for these subordinates and mediate an immediate benefit by reducing the chances of aversive interaction between them.
Most importantly, it also helps subordinates in securing their future generation by minimising the mortality risk of their altricial (helpless) infants, which are highly vulnerable. Therefore, dens are crucial for the co-existence of subordinate meso-carnivores. Particularly in this era where large carnivores dominate most conservation policies.
The above-discussed advantages of dens are highly site-dependent. It means site attributes will determine the efficacy of a den. Scientists have been exploring the factors that characterise an optimal denning site.
In our study, we have also explored the factors determining the den site selection by striped hyenas. The study was conducted in the Sathayamangalam-Mudumalai tiger reserve landscape.
The landscape is part of a major tiger conservation complex in India, which houses a small population of striped hyena. The population is the last remaining major population of striped hyenas in southern India.
Therefore, the population is critical for conserving the species in the entire peninsular India. This population co-exists with a high density of its three competing carnivores tiger, leopard and dhole. This makes the population more vulnerable to interspecific predation.
Therefore, den site selection in response to these competing carnivores was one of the prime focuses of the study. During our study, we recorded all hyena dens from an area that is more frequented by its co-predators.
Hyena is a scavenger, largely dependent on kills made by co-predators to meet its dietary requirements.
Therefore, we believe the selection of dens in this area is probably to secure easy access to food in the form of carcasses. Parallelly this also imperils the species to aversive interaction.
Hyenas were found to select dens on mountain slopes to offset this threat. Mountain slopes are energy expensive, which means transgression through the slope requires a higher amount of energy than plain.
Therefore, slopes restrict the movement of other competing carnivores mostly to the plain. This, in turn, provides foothold denning sites which facilitate the existence of subordinate hyenas in this large carnivore-dominated landscape.
This study provided deep insight into the denning ecology of the hyena and pegged the importance of undulating terrain (slopes and mountains) in conserving this vulnerable species.
Prevailing conservation policies in India are primarily large carnivore centric and we generally ignore the top-down effect (i.e., the desisting impact of large carnivores over their subordinates).
Conservation of each species is important to maintain the delicate balance between the different evolved systems of the earth.
Denning is one of the evolved mechanisms that can potentially offset the top-down effect and needs to be understood properly to facilitate the co-existence of sub-ordinate species like a hyena.
A full-length research article published in the journal Tropical Ecology can be requested on ResearchGate by visiting this web link.
Views expressed are the authors’ own and don’t necessarily reflect those of Down To Earth
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