An Investigation Into Climate Change And The Affect It Has On Cheetahs (Acinonyx jubatus)

Friday 1st December 2023 - Sydney Hayden

Highlights

Cheetahs now occupy just 9% of their historical range and fewer than 7,000 remain in the wild.
Rising temperatures are limiting safe hunting conditions and forcing cheetahs to hunt at night, increasing conflicts with lions and hyenas.
Core body temperature limits (40.5°C) mean cheetahs must stop sprinting sooner, reducing hunting success.
Population models show decline (λ = 0.95), with cub survival at only ~5%.
Severe genetic bottleneck: cheetahs have lost ~90% of their genetic diversity, increasing vulnerability.
Effective conservation requires community collaboration, habitat corridors, and climate-resilient planning, not just fenced reserves.

Abstract

Cheetah (Acinonyx jubatus) populations have experienced dramatic declines in the 50 years that they have been studied. Man-made threats are the main cause for the population decline alongside the Cheetahs unusually low genetic diversity due to genetic bottlenecking [1]. One man-made threat is climate change, the increasing of temperature across Africa is affecting the Cheetahs hunting ability with the Cheetahs stuck at a trade-off between overheating or facing their larger nocturnal predators. Previous research has demonstrated that Cheetahs are not suitable for many conservation efforts and programs, with very little further research being put into finding protection that works for the Cheetahs. With the use of mathematical analysis and data manipulation I have shown the increasing threats greenhouse gas concentration are creating alongside the Cheetahs vast reduction in geographical range and declining population. A major issue found within the data reviewed is the amount of fragmentation the Cheetah populations have experienced; how in order to protect their genetic diversity during breeding efforts you must bring together Cheetahs that could be opposite ends of the continent from each other.

Introduction

Cheetahs (Acinonyx jubatus) historically have a predominantly diurnal (day time) activity [2], meaning they can withstand high temperatures across their habitat. However, due to pressure from climate change causing a global temperature increase they are being forced to adopt a more crepuscular (dawn and dusk) activity [3]. Wild Cheetahs face natural predators that mostly hunt at night [4]; thus they are confronted with a decision between a trade-off of battling with heightened daily temperatures or the risk of predation during the night [5]. Hunting during the daytime requires different adaptations to the cats that hunt at night; one of these is the Cheetah’s eyes. Their eyes have a visual streak which is a dense cell distribution in an oval shape, Cheetahs streaks run horizontally: this is an adaptation specialised to vertebrates that are locating prey along the horizon in the daytime [6]. Cheetahs spend most the day-time waiting for prey to come to them, whilst in the morning and late afternoon will actively hunt; they move very little distances during the day and often not at all during the night [7]. The average surface temperature has increased by around 0.2 oC every ten years over the last thirty years [8], in parts of Africa where Cheetahs that have been studied inhabit there are even higher temperature anomalies than the rest of the world as they are vast remote regions. Global studies on climate change and wildlife poses the question: is climate change controlling behaviour of animals? It has been found that the areas and habitats many terrestrial animals occupy have been shifting over the years towards the poles; studies have found the majority of species that have changed is due to the ever increasing threats of climate change [9], this provides incentive to further look into what adaptations in animals climate change is causing.

Cheetahs are adapted to possess an active behaviour during the day with the majority of their hunting occurring during the dawn and dusk, when it is cool [10]. This is one of the ways they avoid predation. The increasing global temperature is forcing Cheetahs to hunt closer to the night; this is starting to create an overlap with the hunting patterns of predators such as lions and hyenas [4]. Investigated here are the impacts rising day-time tem peratures have on Cheetahs in Africa. Different challenges I looked into are: (i) climate change in Africa with relation to predation problems when Chee tahs are forced to adjust their circadian cycle; (ii) habitat loss encountered by Cheetah populations, including its effects on human-wildlife conflict; and (iii) a population projection of the Cheetahs in Tanzania, looking at their decline and addressing issues with their limited genetic diversity. The re sults found show the Cheetah populations across Africa are declining. This was theorised to be mainly due to human interactions such as farmers pro tecting their livelihood, recreational hunting, increasing urbanisation and the increasing greenhouse gas emissions. What does this mean for the lo cals? We need better education on the importance of biodiversity and the role Cheetahs play in the community as these animals are not well suited for other means of conservation. Cheetahs could go extinct very soon with out proper protection. This could cause catastrophic affects and a chain reaction for many of the species that coexist with the Cheetah populations across Africa.

Methodology

Study Species

The Cheetah (Acinonyx jubatus) is commonly known for being the fastest land mammal [11]; achieving speeds of up to 29ms−1 [12], they occupy niches including savannahs, mountains, and deserts. Within this paper the subspecies of the African Cheetah is focussed on. There is much more data on the Cheetah’s occupying Africa than the small remaining population of less than 100 Asiatic Cheetahs occupying Iran [13]; hence, the main por tion of analysis of populations within this paper is focussing on the afore mentioned African Cheetah. There has been a range of wild and captive populations that have been studied since the 1980s until recently that are utilized throughout the report. Looking at how the species gather together, the females with their cubs and only some males live in groups known as coalitions; the rest of the males roam solitarily [14]. The current popula tion is estimated at around 7100 individuals within only 9% of their historic range; around 6500 of these are mature individuals, with an estimated area of occupancy of around 3123830 km2 and this has declined significantly since the 1980s [15]. The IUCN red list classed this species as ‘vulnerable’ and ‘declining’ according to the May 2021 assessment [16].

Climate Change

The first concept within climate change important to mention is the rep resentative concentration pathway (RCP), this is IPCC’s trajectory of the greenhouse gas concentrations [17]. The different RCP’s show the variety of possible futures of greenhouse gas concentrations allowing prediction of temperature anomalies. When looking into climate change and temperature increases, I narrowed down the focus from global to just the continent of Africa where our Cheetahs inhabit. The data used throughout the report is the mean temperature annually and is courtesy of the ‘Climate Change Knowledge Portal’ [18]; alongside some data from MetadataWorks [?]. These were used in combination with the data of 19 different countries where Cheetahs are found given by the IUCN red list: Algeria, Angola, Benin, Botswana, Burkina Faso, Central African Republic, Chad, Ethiopia, Kenya, Mali, Mozambique, Namibia, Niger, South Africa, Tanzania, Uganda, Zambia, and Zimbabwe [16]. From this data we can generate a prediction of the temperature trends in the future for Africa.

Habitat Loss

Cheetahs only occupy 9% of their historical geographical range as of Durant’s study in 2017 [15]. From the earliest data I could find from Myers in 1975, he had an estimate of the Cheetah population to be around 15000, with their geographical range at the time was thought to be double in 1960. Following this the IUCN red list provides the current geographical range at around 3,100,000 [16]. Habitat loss can be due to a number of factors affecting the Cheetah: (i) agricultural interruption to their habitat, (ii) development of urban areas, and (iii) human recreational activities and war [15].

Species Decline

I assessed the declining nature of the species. Using data courtesy of Co. Madre, I intend to carry out population predictions of the population from Tanzania [19]. Left is a transition rates table created from the Comadre table for Acinonyx jubatus. Following this on the right is a population projection matrix from which transition rates can be made.

From these, predictions for the Cheetah population in Tanzania can be created. The species has three main reasons for decline that I will focus on: (i) the forced overlap of the Cheetahs with their predators’ circadian cycle, (ii) the threats imposed by humans, and (iii) their severely reduced genetic diversity.

Results

Climate Change

With the use of the studies on current greenhouse gas concentrations (GHG) in relation to temperature anomalies, I extrapolated to predict global temperature anomalies in two future greenhouse gas scenarios. The data I used was for scenarios RCP 2.6 (a concentration occurring from minimum emissions) and RCP 8.5 (a concentration occurring from maximum emissions); this is due to looking at the worst possible outcome and the best outcome. If focus is based on the worst, then any adaptations or conservation efforts put in place will still be beneficial even if we do not reach RCP 8.5. An important intermediate to note is RCP 4.5; this is the most probable scenario, which takes into account the limit of non-renewable energy without including any climate policies currently being put into place.

Figure 1: Projections of temperature anomalies using pre-existing data. The graphs show predictions of temperature anomalies in the years 1979 to 2100. I plotted two lines, one for a future with a concentration occurring from minimum emissions RCP 2.6 (the purple line) and one for a future with a concentration occurring from maximum emissions RCP 8.5 (the green line). The projection corresponding to RCP 2.6 plateaus at around a 1 K increase from what the temperature from 2040 to 2100 should be. On the other hand, the projection corresponding to RCP 8.5 exponentially increases until it cuts off at a 4 K increase from what the temperature at 2100 should be.

When looking at the projections for the representative concentration pathway (RCP) in Figure 1, you can see there is an increase with both RCP 2.6 and RCP 8.5. Regardless of the contribution to the greenhouse gas concentrations, the temperature anomaly still increases; if, however, it plateaus like RCP scenario 2.6, it will give the ecosystem a chance to adapt, as the temperature will be stable and will not experience dramatic fluctuations. Additionally, I looked at the temperature change across Africa. In the parts of Africa where Cheetahs that have been studied inhabit, there are larger temperature increases than the global average, as they are vast remote regions. Using temperature data from each of the countries Cheetahs inhabit, the trend over the last 100 years can be visualised.

Figure 2: Temperature across Cheetah inhabited countries in Africa. The mean temperature annually from 1901 to 2021 [18] alongside 19 different countries where Cheetahs are found given by the IUCN red list: Algeria, Angola, Benin, Botswana, Burkina Faso, Central African Republic, Chad, Ethiopia, Kenya, Mali, Mozambique, Namibia, Niger, South Africa, Tanzania, Uganda, Zambia, and Zimbabwe [16].

The temperatures in every country where Cheetahs are found in Africa all display an increase in temperature in Figure 2. This is as predicted, considering the climate crisis the world is currently facing. From this, the average temperature increase across Africa could be taken and produced in a graph.

Figure 3: Projections of the average temperature across Africa over the last 100 years.

Looking at Figure 3, the constantly fluctuating temperatures are of hindrance to the communities across Africa. Most species are not adapted to survive large temperature changes this frequently. Cheetah’s hunting techniques are affected by the daytime temperature. Cheetahs are regulators; they utilise energy to maintain a core body temperature. They store from 70 to 90% of the heat produced whilst sprinting, with the run ceasing when the Cheetah's rectal temperature reached 40.5 oC [20]. Therefore, Cheetahs should be as cool as possible before starting their hunt. The coolest time is during the night, so the consequences of rising temperature could be posing a threat to the Cheetahs' diurnal activity pattern; for Cheetahs to maintain their stable body temperature, they would have to hunt whilst their predators started to become active at night-time [21]. There is a trade-off between hunting during the high heat and overheating, or facing their larger nocturnal predators [2]. If climate change continues at its current rate or RCP, the Cheetah will be unable to continue to be active within its daytime niche.

Habitat Loss

With very limited research on historical geographical ranges of Cheetah populations, their habitat loss cannot be looked at on a year-by-year basis but rather a then and now approach. From the data I could find, I looked at three different points of Cheetah geographical distribution: historical, 1974, and current.

Figure 4: Distribution of Cheetahs across Africa. Polygons overlayed on the map of Africa where Cheetahs occupy. The yellow is the historical ranges of the cheetah; the purple is where the cheetahs occupied in 1974; and the blue is where they occupy now. Both the historical and current data was compiled by the IUCN red list [16], with the 1974 data being found from Myers [22].

There are a number of reasons for their dramatic decline in geographic range that can be seen in Figure 4. The largest number of Cheetahs is found within Namibia, Botswana, South Africa, and Zimbabwe, where they are under threat from human-wildlife conflict [23]. As Cheetahs live a low densities, they require large ranges of land, so are particularly vulnerable to habitat loss and fragmentation [15]. The majority of Cheetahs live on unprotected land. This gives rise to competition between wildlife and people due to living in increasing proximity to each other [24]; human activities impose on the Cheetah habitat. Cheetahs are hunted recreationally and killed by farmers when there is little other prey for them to hunt [25]. Therefore, protection is needed for the Cheetahs as Africa’s urban scene is developing and growing, pushing animals closer together, creating threats from each other and from humans. Cheetahs have also become almost extinct across Asia, with only one surviving population in Iran [26]. If the Cheetahs' geographic range continues shrinking at this rate, in not many years, could they be too fragmented to survive

Species Decline

From data gathered on a Cheetah population in Tanzania, it is shown that Cheetahs are a declining species.

Figure 5: Cheetah population prediction for a cheetah population in Tanza nia [19]. Using a population prediction matrix you can see every age class decreases over time without intervention. Adults have much higher survival rates than cubs.

Figure 5 demonstrates that this Cheetah population is declining. Between 6 months and 42 months, Cheetahs have a very low chance of survival. Cubs are estimated to have only around a 5% chance of survival [27]; this would lead to it being extremely hard for the Cheetahs as a species to replenish their population naturally. Moreover, I created a series of plots representing the percentage change we would need to change the population from declining to increasing.

Figure 6: Graphs of the percentage change needed to change the eigenvalue from approximately 0.95 to a new eigenvalue at 1.1 for the cheetah population to increase. The visualisation has the same layout as our matrix, with each subplot representing the growth rate. The subplot representing the adults in the population has been enlarged in the bottom right; this shows we would need a 23% increase in transition rates, increasing survival of adult cheetahs to change the eigenvalue from 0.95 to 1.1.

Increasing the population of adult Cheetahs and sustaining a population increase is feasible, as shown in Figure 6. The only way for the Cheetahs to become an increasing population under this analysis is for the survival of the adult Cheetahs to be improved by around 20%. This is thought to be easily done with most cats in Africa by creating reserves and protected areas; however, when it comes to the Cheetah, it is not that simple. The Cheetah needs vast ranges of land, as mentioned before, alongside this, they do not live in close proximity to their larger predators. Within reserves, Cheetahs would be closer than usual to their predators and at more risk of attack. There is also a major problem with breeding Cheetahs, as they have an unusually low genetic diversity. This means the species does not have a buffer for any environmental changes or new diseases. A study was conducted that found a variety of Cheetahs possessed the same proteins; they were ‘electrophoretically’ identical [28]. If we were to breed a population of Cheetahs, we would have to bring together Cheetahs from different parts of the continent to try and introduce as much genetic diversity as possible. Overall, Cheetahs have lost around 90% of their variation due to a multitude of past historical events [29].

Discussion

Cheetah populations are currently declining. The best approach to Cheetah conservation is through education; if human-wildlife conflict can be reduced, then there is less worry about other methods of conservation, which impose just as many risks as benefits. Long-term research has revealed human threats to Cheetahs are the main source of mortality [30]; Cheetah removal was used as a precaution from farmers protecting their lands, so with a suitable learning structure in place, farmers could work alongside the natural populations. This investigation into the species runs parallel to other studies cited throughout the paper. Cheetahs are still facing the same threats and decline as they were when Myers first investigated them in 1975. One reason why we have not seen many conservation efforts or awareness for Cheetahs is the scientific implications they face. When attempting breeding efforts, the breeders must be aware of the low genetic diversity. There have also been issues with females being housed together in captivity; they suffer from socially induced reproductive failure. One study showed their levels of faecal oestradiol in their reproductive cycles are drastically reduced when housed in pairs [31], so not only do they have a low breeding chance, but also high cub mortality, making it really hard to breed Cheetahs. Reintroduction of Cheetahs could also be an unrealistic conservation goal. This year, some Cheetahs were brought back to India against advice that they were not suitable for translocation programmes [32]. Scientists are unsure how well as a population they will survive. In conclusion, this specialised field has few recent studies on the Cheetah, with most of the data coming from studies performed before 2000. There is scarce information and very limited tracking on where the populations occupy. Many believe the IUCN red list assessment of ‘vulnerable’ is an underestimate of how threatened the Cheetahs actually are. To further the field, more effort should be put into protecting wild Cheetahs and educating locals and cooperation from communities is needed to avoid unnecessary declines. If the Cheetahs become extinct, it could cause a cascade of problems due to the reduction in biodiversity and disruption to food chains in communities across Africa. Cheetahs are dying out due to humans; not only do we cause human-wildlife conflict, but the climate crisis is affecting us as well as the animals we live with too.

References

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