Course:CONS200/2023WT2/The Story of Two Big Cats: Leopards and Tigers

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A Leopard with Duiker (prey), near Exeter River Lodge, Sabi Sand, Mpumalanga, South Africa.

Large carnivores are facing critical threats, leading to sharp declines in their numbers and habitats due to habitat loss, persecution, exploitation, and prey depletion[1]. Against this backdrop, exploring how carnivores achieve regional coexistence through differentiation in various ecological niche dimensions has become a hot topic in conservation biology and ecology in recent years. Spatial, temporal, and trophic niches are three typical dimensions of niche construction, describing an animal's ecological position and resource use[2]. When multiple species coexist in the same community, they inevitably interact across these niche dimensions. Animals can adjust their niche width and range across these dimensions through adaptation or behavioral changes in the face of interspecific competition, thereby reducing competition while maximizing ecological benefits[3][4]. The plasticity and adaptability of carnivores in spatial, temporal, and trophic niches are evolutionary outcomes to mitigate competition, which can promote the coexistence of different species[5]. Tiger (Panthera tigris) and leopard (P. pardus) play crucial roles in maintaining the stability of community structure and function as large flagship carnivores [1]. IUCN list tiger as 'Endangered' and leopard as 'Vulnerable'[6]. Their biology, ecology, and behavior have been well-studied, providing us with an opportunity to investigate the competitive interactions and coexistence mechanisms among top predators. Several approaches have been developed to support the survival and coexistence of tigers and leopards. Further research and long-term data collection are necessary to develop better conservation planning for the survival and coexistence of tigers and leopards and to assess the effectiveness of existing conservation approaches.

Friend or Enemy - Can Tigers and Leopards Coexist?

The question of whether tigers and leopards can coexist together is an important topic because tigers and leopards are sympatric predators (predators inhabiting the same geographical area and thus frequently encounter one another) and are governed by density, distribution, diet, activity overlaps, and behavioral strategies[7].

Food Selection

Tiger catching its prey in South China.

Coexistence has happened in Nagarahole National Park, India when large prey (>175kg) and Medium-sized prey (30-175kg) were in rich supply. Leopards avoid each other on a fine scale or behaviourally, with exclusion not being done by tigers[2]. However, in any other scenario where both sized prey were not in a rich supply, it would lead to tigers occupying the prime habitat while excluding leopards, which is not coexistence[2]. Another point that would facilitate coexistence is the fact that leopards are more active in the evening before the main activity period of tigers at midnight[8].

When prey populations are less abundant, intraguild predation (killing and eating of another potential competitor of a different species) may occur. In this case, tigers (65-306 kg) are preying on leopards (28-90 kg) because they are quite a bit larger. In order for coexistence to occur, both groups need to have an abundance of prey[8]. This coexistence usually occurs in the form of leopards stalking the outside of an area, with tigers being on the inside. It is argued that this occurs because of leopards trying to avoid social interference or possibly because leopards like to stay closer to human populations, possibly due to being able to exploit domestic animals in close proximity to humans[8].

Spatial and Temporal Factor

Leopard on a tree.

In northeast China, researchers at the Hunchun Nature Reserve employed camera traps throughout 2013 to probe the dynamics between Amur leopards, Amur tigers, their prey, and the effects of human activities. The findings revealed that Amur leopards prefer daytime and twilight for their activities, rarely overlapping spatially or temporally with Amur tigers, yet often intersecting with prey species[9]. The presence of humans, along with disturbances from vehicles, domestic dogs, and cattle grazing, notably influenced the spatial distribution and activity patterns of Amur leopards, underlining the urgency of tailored conservation strategies to mitigate human impacts.

Tiger lying under vegetation cover to avoid hot temperature.

Moreover, the investigation underscored the crucial role of spatial separation in the coexistence of Amur leopards and Amur tigers. Leopards tend to avoid regions frequented by tigers and are more active during the day, in stark contrast to the tigers' preference for nocturnal or crepuscular times[9]. These insights into prey preferences and the nuances of human influence are vital for formulating effective conservation measures, highlighting the intricate balance required to maintain carnivore coexistence in human-impacted environments.

Vegetation is also a critical spatial factor in wildlife habitats.The availability of vegetation significantly influences the behavior of tigers and leopards, especially in providing essential hiding and cover. Vegetation offers protection against harsh conditions and predation by providing both thermal cover and hiding spots, which are vital for increasing the survival rates of these predators in their natural habitats[10]. The presence of diverse vegetation supports a richer consumer group, which in turn fosters coexistence between Amur tigers and leopards[10]. The complexity of the vegetation and the variety of available resources contribute to this diversity, ensuring a sufficient and varied consumer base that enhances ecological balance[10].

Anthropological and Environmental Impact

Humans and climate change pose significant challenges to the conservation and coexistence of tigers and leopards. The impacts of human civilization alter the environment in which tigers and leopards exist. Similarly, climate change alters ecosystems in numerous ways. The change in temperature and precipitation impacts the distribution and abundance of prey species, potentially leading to increased competition between tigers and leopards for resources. Conservation efforts must consider these two challenges to be able to implement effective measures to protect and restore habitats, ensuring the long-term survival of both tiger and leopard populations and supporting their coexistence.

Human Contribution

Deforestration.

Human activities influence the coexistence of tigers and leopards. Deforestation, urbanization, and agricultural expansion pose a threat in the form of habitat destruction and fragmentation. These activities shrink the natural habitats of wildlife, including large cats. The effect of human activity is visible in certain regions. One such example is the decline of wildlife abundance in all habitats in the Terai region of Nepal as a result of human activity[11].

The abundance reduction of large species of prey can impact the prospect of the coexistence of tigers and leopards in particular. Tigers prefer large-sized prey but can shift to medium-sized prey species if large species of prey are not abundant. As leopards rely on medium-sized prey, the shift in tigers competing for the same resource can create competition that hampers the coexistence of tigers and leopards. Species richness at various size classes of prey is a key factor that affects the dynamics of competition between tigers and leopards [2].

Any human activities that affect species richness can have an effect on the prospect of tigers and leopards coexisting. Conservation initiatives that focus on preserving the natural habitats of tigers and leopards are key in promoting the coexistence of the two large cats. To maintain the population performances of large cats, the likes of tigers and leopards, the creation of undisturbed areas is a prime criterion[12]. The limitation of such initiatives lies in the possibility of the displacement of people in the name of conservation.

Global temperature change over the past 50 years.

Climate Change

The distribution and behavior of species, including tigers and leopards, are affected by changes in the mean climate state and extreme events related to the shift in climate . Similarly, ecosystem structure and function are also affected by climate change [13]. Ecological biomes globally are close to critical thresholds for significant ecosystem change, and parts of boreal forest belts worldwide that serve as the habitat of the Amur tiger and Amur leopard are no exception[14]. Due to the low plant species richness and species-poor communities in many of the secondary or planted forests inhabited by the Amur tiger and leopard in China, sensitivity to environmental disturbance caused by climate change increases[15]. Daily activity patterns of animals such as tigers and leopards may change following rapid shifts in temperature or other climate-induced environmental conditions to match the requirement of energy consumption in a shifted environment . Reproductive timing and reproductive success of the Amur tiger and leopard can be affected by the increased temperature and the related changes in the amount and distribution of precipitation and snowfall as the Amur tiger and leopard have evolved to adapt to cold climates[16].

Conservation Plan of Action

The coexistence of tigers and leopards is a conservation goal worth achieving. Several measures have been applicable all around the world in order to support the coexistence of tigers and leopards. These include programs involving concepts of land sharing, land sparing, and herbivore population management.

Land sparing

The approach of land sparing involves setting aside areas of land for conservation, with human utilization of resources within those areas being moved to other areas of land[17]. In terms of agriculture, the approach of land sparing utilizes a small amount of land footprint outside of the areas set aside for conservation with a relatively high yield for the amount of land used[18]. The relatively high yield generated in agriculture from the approach of land sparing is achievable through a more intensive extraction of resources, as conservation objectives are mainly applicable to areas of land specifically set aside for conservation. Land sparing effectively segregates agriculture and wilderness. The framework generalizing land sparing can be summarized as the separation of production and conservation[19].

An example of the land sparing approach utilization is the establishment of the Northeast China Tiger and Leopard National Park. It was established in 2017 to strengthen the protection of wild animals, especially the protection of flagship species such as tigers and leopards[20]. The Northeast China Tiger and Leopard National Park has set a rescue center and supplementary feeding points in a pilot area to better support the population of tigers and leopards, with farmland being returned to forests, pieces of hunting gear being collected, illegal processing farms being banned, fragmented habitat being restored, and poachers being investigated and dealt with in the pilot area[21]. The pressure of competition between tigers and leopards will decrease as tiger and leopard populations receive support from the Northeast China Tiger and Leopard National Park, making coexistence between the two species more likely.

Land sharing

The approach of land sharing involves setting aside less land for conservation relative to land sparing, with less intensive human utilization of resources to maintain some biodiversity throughout the land[17]. In terms of agriculture, the approach of land sharing utilizes a large amount of land footprint that is friendly for wildlife conservation and a relatively low yield for the amount of land used[18]. Land sharing utilizes patches of agriculture that allow it to mesh with wilderness rather than keep it separate. The framework generalizing land sparing can be summarized as the integration of production and conservation[19]. It is important to note that the concepts of land sharing and land sparing are not mutually exclusive in their use, with both concepts needed for effective biodiversity conservation[22].

Bengal Tiger walking on the dry river bed at Jim Corbett National Park.

An example of the land sharing approach can be seen in the Rajaji-Corbett Tiger Conservation Unit, notably in the corridor habitat known as the Rajaji-Corbett corridor that connects Corbett Tiger Reserve and Rajaji National Park. The Rajaji-Corbett Tiger Conservation Unit is one of the 11 Level-I Tiger Conservation Units identified in the Indian subcontinent with the purpose of long-term conservation of the tiger population. Two protected areas, Corbett Tiger Reserve and Rajaji National Park, made up the Rajaji-Corbett Tiger Conservation Unit. The corridor habitat connecting these two protected areas is known as the Rajaji-Corbett corridor, where people reside in villages. Both tigers and leopards from the two protected areas are known to traverse the Rajaji-Corbett corridor[23]. As such, the Rajaji-Corbett corridor is part of an ecoregion with a notable human population that has a crucial role in tiger and leopard conservation[24]. The land sharing approach implemented in the Rajaji-Corbett corridor allows for habitat connectivity for tigers and leopards from two different protected areas, allowing for an increased range of prey selection for both tigers and leopards that can support the coexistence of the two species.

Herbivore population management

Too much herbivore quantity, exceeding the carrying capacity, can decimate the forest understory shrub layer and trigger a decline in the abundance and distribution of plants that play a role in the survival of tigers and leopards [25]. A population management objective for certain species has been developed in order to promote biodiversity that may help the survival and coexistence of tiger leopards, such as a population management objective for white-tailed deer of 4 deer/km2 in deciduous forest [26]. Similar population management objectives have been made specifically for balsam fir boreal forests, which specify an estimate of compatible deer density in the range of 7.5-15 deer/km2[27].

It has been found that leopard density declines when the total biomass of certain herbivores exceeds a threshold value[28]. In general, there is an expectation of a threshold effect of herbivore density for triggering a significant shift of vegetation change that may influence herbivore population density that directly correlates with predator density the likes of tigers and leopards [29]. To avoid excessive pressure on vegetation abundance and distribution, which could hinder the conservation and coexistence of predators the likes of tigers and leopards, prey or herbivore populations should be managed accordingly [30].

Future suggestion

Further research is necessary to improve the understanding of the components of coexistence between tigers and leopards. Knowledge regarding factors of tigers' and leopards' coexistence will help the development of better conservation actions. Existing plans of conservation would also benefit from long-term data to assess the effectiveness of their implementation. As tigers and leopards are flagship species, their conservation, and possible coexistence are a conservation goal worth achieving. However, it is important to recognize the limitations of certain conservation actions. Funding, displacement of indigenous people, and opportunity costs are important considerations for any action that support.

References

  1. ↑ 1.0 1.1 Ripple, William J.; Estes, James A.; Beschta, Robert L.; Wilmers, Christophor C.; Ritchie, Evan G.; Mark, Hebblewhite; Berger, Joel; Elmhagen, Bodil; Letnic, Mike (2014 Jan 10). "Status and ecological effects of the world's largest carnivores". Science. 343: 6167. Check date values in: |date= (help)
  2. ↑ 2.0 2.1 2.2 2.3 Li, Z; Wang, T (2022). "Competition and coexistence between tigers and leopards in asia". Biodiversity science.
  3. ↑ Schoener, T. W. (1974). "Resource partitioning in ecological communities". Science. 185(4145): 27–39.
  4. ↑ Bruno, J.F. (2003). "Inclusion of facilitation into ecological theory". Trends in Ecology & Evolution. 18: 119–125.
  5. ↑ De Satgé, J.; Teichman, K.; Cristescu, B. (2017). "Competition and coexistence in a small Carnivore Guild". Oecologia. 184(4): 873–884.
  6. ↑ https://www.iucnredlist.org/. Missing or empty |title= (help)
  7. ↑ Chatterjee, B; Sankar, K; Jhala, V; Qureshi, Q (2023). "Spatio-temporal patterns of co-occurrence of tigers and leopards within a protected area in central india". Web Ecology. 23(1): 17–34.
  8. ↑ 8.0 8.1 8.2 Pokheral, P; Wegge, P (2019). "Coexisting large carnivores: Spatial relationships of tigers and leopards and their prey in a prey-rich area in lowland nepal". Écoscience (Sainte-Foy).
  9. ↑ 9.0 9.1 Yang, H.; Zhao, X.; Han, B.; Wang, T.; Mou, P.; Ge, J; Feng, L. (2018). "Spatiotemporal patterns of Amur Leopards in northeast China: Influence of Tigers, prey, and humans". Mammalian Biology. 92: 120–128.
  10. ↑ 10.0 10.1 10.2 Qi, J.; Holyoak, M.; Ning, Y.; Jiang, G. (2020). "Ecological thresholds and large carnivores conservation: Implications for the amur tiger and leopard in china". Global Ecology and Conservation. 21.
  11. ↑ Bhattarai, B. P.; Kindlmann, P. (2012). "Interactions between Bengal tiger (Panthera tigris) and leopard (Panthera pardus): Implications for their conservation". Biodiversity and Conservation. 21: 2075–2094.
  12. ↑ Harihar, A.; Pandav, B.; Goyal, S. P. (2011). "Responses of Leopard Panthera pardus to the recovery of a Tiger Panthera tigris population". Journal of Applied Ecology. 48: 806–814.
  13. ↑ E. Doughty, Christopher; Metcalfe, D. B.; Girardin, C. A. J.; Amézquita, F. Farfán; Cabrera, D. Galiano; Huasco, W. Huaraca; Silva-Espejo, J. E.; Araujo-Murakami, A.; Costa, M. C. da. "Drought impact on forest carbon dynamics and fluxes in Amazonia". Drought impact on forest carbon dynamics and fluxes in Amazonia.
  14. ↑ Seddon, Alistair W. R.; Macias-Fauria, Marc; R. Long, Peter; Benz, David; J. Willis, Kathy. "Sensitivity of global terrestrial ecosystems to climate variability". Sensitivity of global terrestrial ecosystems to climate variability: pp 239-232.CS1 maint: extra text (link)
  15. ↑ LUGO, A. E. "Visible and invisible effects of hurricanes on forest ecosystems: an international review". Visible and invisible effects of hurricanes on forest ecosystems: an international review.
  16. ↑ Qi, Jinzhe; Holyoak, Marcel; Ning, Yao; Jiang, Guangshun. "Ecological thresholds and large carnivores conservation: Implications for the Amur tiger and leopard in China". Ecological thresholds and large carnivores conservation: Implications for the Amur tiger and leopard in China.
  17. ↑ 17.0 17.1 Green, R. E.; Cornell, S. J.; Scharlemann, J. P.; Balmford, A. (2005). "Farming and the fate of wild nature". Science. 307: 1106049.
  18. ↑ 18.0 18.1 Kremen, C. (2015). "Reframing the land‐sparing/land‐sharing debate for biodiversity conservation". Annals of the New York Academy of Sciences. 1355: 52–76.
  19. ↑ 19.0 19.1 Fischer, J.; Abson, D. J.; Butsic, V.; Chappell, M. J.; Ekroos, J.; Hanspach, J.; Kuemmerle, T.; Smith, H. G.; von Wehrden, H. (2014). "Land sparing versus land sharing: Moving forward". Conservation Letters,. 7: 149–157.CS1 maint: extra punctuation (link)
  20. ↑ Wen, D.; Qi, J.; Long, Z.; Gu, J.; Tian, Y.; Roberts, N. J.; Yang, E.; Kong, W.; Zhao, Y. (2022). "Conservation potentials and limitations of large carnivores in protected areas: A case study in northeast china". Conservation Science and Practice. 4.
  21. ↑ Song, T. (2020). "The exploration of China's National Park System Pilot Project: Taking northeast china tiger and Leopard National Park System Pilot area as an example". International Journal of Geoheritage and Parks. 8: 203–209.
  22. ↑ Scariot, A. (2013). "Land sparing or land sharing: The missing link". Frontiers in Ecology and the Environment. 11: 177–178.
  23. ↑ Johnsingh, A. J. T.; Negi, A. S. (2003). "Status of tiger and leopard in Rajaji–Corbett Conservation Unit, Northern India". Biological Conservation. 111: 385–393.
  24. ↑ Olson, D. M.; Dinerstein, E. (2002). "The global 200: Priority ecoregions for global conservation". Annals of the Missouri Botanical Garden. 89: 199.
  25. ↑ ROONEY, THOMAS P.; M. WIEGMANN, SHANNON; A. ROGERS, DAVID; WALLER, D. M. "Empobrecimiento Biótico y Homogenización en Comunidades de Sotobosque en Bosques No Fragmentados". Biotic Impoverishment and Homogenization in Unfragmented Forest Understory Communities: pp.787-798.CS1 maint: extra text (link)
  26. ↑ De Leo, Giulio A.; Levin, Simon. "The Multifaceted Aspects of Ecosystem Integrity". The Multifaceted Aspects of Ecosystem Integrity.
  27. ↑ Tremblay, Jean-Pierre; Huot, Jean; Potvin, François. "Divergent nonlinear responses of the boreal forest field layer along an experimental gradient of deer densities".
  28. ↑ Qi, Jinzhe; Shi, Quanhua; Wang, Guiming; Li, Zhilin; Sun, Quan; Jiang, Guangshun (Yan). "patial distribution drivers of Amur leopard density in northeast China". patial distribution drivers of Amur leopard density in northeast China: pp.258-265. |first6= missing |last6= (help); Check date values in: |date= (help)CS1 maint: extra text (link)
  29. ↑ Sasaki, Takehiro; Okayasu, Tomoo; Jamsran, Undarmaa; Takeuchi, Kazuhiko. "Threshold changes in vegetation along a grazing gradient in Mongolian rangelands". Threshold changes in vegetation along a grazing gradient in Mongolian rangelands: pp.145-154.CS1 maint: extra text (link)
  30. ↑ Qi, Jinzhe; Holyoak, Marcel; Ning, Yao; Jiang, Guangshun. "Ecological thresholds and large carnivores conservation: Implications for the Amur tiger and leopard in China". Ecological thresholds and large carnivores conservation: Implications for the Amur tiger and leopard in China.


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