ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)

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(04-23-2019, 08:11 PM)Rishi Wrote:

(04-23-2019, 03:13 PM)Sanju Wrote: Indian tigers are highly stressed due to human disturbances
   

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Sariska tiger   | Photo Credit: Special Arrangement

Tigers in the Kanha reserve had the highest faecal glucocorticoids metabolites level (markers for stress)

Compared with 200-odd Amur tigers in Russian Far East, the Bengal tigers in three tiger reserves in India — "Bandhavgarh, Kanha, Sariska" — are about 20% more stressed, a study found.

The Indo-Russian team measured the stress level by studying the glucocorticoids metabolites present in the faeces of tigers.

“Increased stress level for prolonged periods will affect the immunity and fitness of tigers. Most importantly, elevated stress negatively impacts reproductive hormones which can lead to reduced fertility and reproductive failure. We have earlier found captive elephants showing compromised reproductive cycle due to stress,” said Dr. Govindhaswamy Umapathy from the Laboratory for the Conservation of Endangered Species (LaCONES) at the Centre for Cellular and Molecular Biology (CSIR-CCMB), co-author of a paper published in the journal PLOS ONE.

Tigers in the Kanha reserve had the highest faecal glucocorticoids metabolites level (markers for stress) while tigers in the Bandhavgarh reserve had the lowest level and comparable with the Amur tigers of Russia.

“Though there is a variation in the concentration of glucocorticoids metabolites in tigers in the three reserves, there is no significant difference in the stress levels. The elevated stress in Bengal tigers might be due to anthropogenic disturbance,” says Vinod Kumar, Technical Officer at CCMB and a co-author of the paper.

High population density
While the tiger reserves in India are smaller than in Russia, the anthropogenic disturbances are very high in Indian reserves.

Besides high anthropogenic stress, tigers in the three reserves experience higher population density compared with Amur tigers in Russia. At 11.33 tigers per 100 sq km, the density of tigers is many times higher in India compared with Ussuriisky reserve in Russia (0.15 tigers per 100 sq. km).

Quote:“Anthropogenic disturbances and higher population density could be causing higher stress in Indian tigers,” Dr. Umapathy says.

“A 2015 study by our team found that tigers reintroduced in Sariska reserve experienced high stress due to anthropogenic disturbances,” Dr. Umapathy says. Besides high vehicular traffic, tigers in the Sariska reserve encounter herders, villagers who visit the forest for collecting wood and livestock grazing.

As a result, the reproducing ability of Sariska tigers reduced.

Unlike Sariska, the Panna tiger reserve faces less anthropogenic disturbances.

As a result, three of the five reintroduced tigresses in Panna reserve produced "multiple litters successfully in four years", while in Sariska a tigress could successfully breed only once after four years.

...Wow. And they simply didn't even skim over the possibly of involvement fact that tiger density in India is 5 times higher than Russia! No word on differences between stress hormone level in tigers from core & buffer either.

Here quote from that study:


"We hypothesis that high anthropogenic stress might be the reason for higher FGCM level in Bengal tigers. India is one of the most populated countries over the world (human population density is 402.8 individuals/km2 ). In Russian Far East (inhabited by the Amur Tiger) human density is extremely low (10 individuals /km2 ). In India tigers’ home ranges are significantly smaller than in Russia [32, 33], they are situated in tigers’ reserves and national parks which are visited regularly by tourists. Number of visitors/tourists was very different between Russian (less than 40, in reserves 2–5 persons/day) and Indian (395–509) study sites. Anthropogenic stress (short distance from villages) may increase stress level in Carnivores [43, 44], including Bengal tigers and even lead to some problems with their reproductive abilities [22]. Tigers’ fecal glucocorticoids PLOS ONE | https://doi.org/10.1371/journal.pone.0214447 April 10, 2019 7 / 11 Possibly, visitors effect on Tiger reserves and National Parks may increase stress level and decrease welfare of tigers in India. The effect of visitors on FGCM level was described for other carnivores (grey wolf, Canis lupus [45]). 
The second hypothesis associates high cortisol level in Bengal tigers with the higher tiger population density in this region in comparison to Russian Far East. The density of tigers is many times higher in India (for example, a density of 11.33 individuals /100 km2 was described for Wayanad Wildlife sanctuary, Kerala [46] while in Russia, in Ussuriisky reserve, tigers’ density approximates 0.15 individuals /100 km2 ) [47]. Normally tigers of the same sex may compete for the territory and high density of conspecifics may result in higher cortisol level. However, this hypothesis, while supported by the data on solitary living rodents [48, 49], was never tested for carnivores.
To sum up, Bengal tigers had higher FGCM level than Amur tigers in winter (dry season in India). Many factors may affect stress/welfare level of animals. Increase of FGCM level may be caused by anthropogenic pressure, sexual intercourse, hunger, low air temperatures, conflicts with conspecifics or sympatric species. Bengal tigers had much higher density of potential prey than Amur ones, with supposed hunger (limitation of food) being less probable in India. Winter temperatures are much lower in Russian Far East (-10-40˚C) than in India, so this factor does not seem to affect FGCM level in Bengal tigers. Both subspecies have food competitors among sympatric species of carnivores, however, in India all of them are much smaller than tigers although in Russia brown bears (Ursus arctos) may be dangerous to the Amur tigers at the Rissian Far East. Most likely, the higher level of glucocorticoids in Bengal tigers might be due to high anthropogenic disturbance [23] or/and high density of tigers, which will result in higher contacts with the conspecifics (including aggressive and sexual contacts) or their marking points or footprints. However, a detailed investigation is required to understand the reasons of this phenomenon."

Link to that study here:
https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0214447&type=printable Reply