Prey of the Amur Tiger

[brobear]

Seasonal food habits and prey selection of Amur tigers and Amur leopards in Northeast China  

Published: 02 May 2018 
 
www.nature.com/articles/s41598-018-25275-1/ 
 
Abstract:   
  
We analyzed the scats of Amur tigers and Amur leopards, and examined their annual and seasonal food habits in Northeast China to comprehend their coexistence. Wild boar had the highest annual and seasonal consumption frequencies by the tigers, while both roe deer and sika deer were mostly preyed by the leopards annually. The three species appeared to be the key preys in terms of high proportion of consumed biomass by the two felids. Our data also revealed numerous mid-sized carnivores and small mammals included in the two felids’ food list. We used the relative abundance and biomass density estimation in prey density estimation to calculate the prey preferences of tigers and leopards, and both methods confirmed that Amur tigers strongly preferred wild boar. However, preference estimations of Amur leopards were not consistant, or even opposite to one another from the two methods. The results of the study suggested that prey preference of predators is largely determined by body size of the prey species. Variation in diet composition of the two felids suggests that resource partitioning may contribute to their coexistence.

[brobear]

Introduction:

Both Amur tiger (Panthera tigris altaica) and Amur leopard (Panthera pardus orientalis) are endangered felids on the list of IUCN and the subspecies of both genera distributing in the northernmost of the ranges of the species. Habitat loss, landscape fragmentation, prey depletion and poaching have contributed to the decline of the Amur tiger from more than 3,000 to about 500 during the past century1,2,3, while the Amur leopard, to less than 100 individuals4. The Amur tigers are currently existing in two separate populations: a larger one in the Sikhote-Alin Mountains of Russia (415–490 individuals)5,6, and a much smaller one, almost isolated from the larger one, in southwestern Primorsky Krai, Russia, and the nearby Hunchun region in China4,7,8. The Amur leopards occur as a small single population co-existing with the smaller tiger population6,9,10.

Prey availability is one of the principal drivers of tiger and leopard distributions and abundance11. Tigers and leopards prefer prey species of their own sizes12,13, suggesting that preferred species of the Amur tiger and Amur leopard are likely different, thereby reducing competition for resources and increasing the likelihood of co-existence14,15,16,17. Investigation of their food habits and prey selections would provide a better understanding of the predator-prey relationship and help define conservation priorities for both felids.

Food habits and prey selection of Amur tigers and leopards have been widely studied3,18,19, mostly based on kill sites found by snow tracking or telemetry. Due to the difficulties of finding kill sites of small animals, such methods would overestimate large prey items in the diet14,20. A widely used field method for examining predator diets is to identify undigested parts (hair, hoof or tooth) from scats of the predators comparing with the reference of potential food items15,20,21,22,23,24. This is a more objective approach with less bias. Furthermore, faecal analysis method is relatively easier in obtaining samples with non-invasive procedure15.

In Northeast China and Far East Russia, available prey in terms of secondary productivity is lower than in more productive habitats in the tropical and subtropical areas, a fact that may aggravate competition between the two native carnivores. Both are “ambush” predators (versus cursorial predators)25 that increase the likelihood of dietary overlap, despite the differences in body sizes. In Russian Fareast, it has been reported that Amur leopard had more diverse prey than Amur tiger did20,24. While such studies are rare in Northeast China.

In this study, we used scats collected from the tiger/leopard areas of Northeast China to explore their prey profiles for the following objectives: (1) to determine the seasonal frequency of occurrence and relative biomass contribution of the principal prey species in predator diets; (2) to evaluate the seasonal difference in prey selection using different methods in estimating prey availability-the relative abundance and biomass density methods; (3) to examine the diet profiles to comprehend resource partitioning and ecological sympatry of the tigers and the leopards in the study area of Northeast China. We hypothesized that the resource utilization of tigers and leopards would be partitioning in their sympatric range in order to reduce the competition.

[brobear]

Results:

After excluding the scats composed of grass, sands, and unidentifiable objects, we had a total of 217 valid tiger scats (80 in summer, 115 in winter and 22 no detailed time records), and 52 leopard scats (23 in summer, 25 in winter and 4 no detailed time records) collected from January 2014 to December 2016. Among them, all contain one prey item, but 29 tiger scats and 7 leopard scats that contained two prey items.

Camera trap data from August 2014 to January 2015 were used to calculate the relative abundance index (RAI)26 of three main prey species as the relative availability of the prey. The RAI values for roe deer (Capreolus pygargus) were the highest in both winter (1.947) and summer (4.459), while the RAIs for sika deer (Cervus nippon) (0.548 and 1.835 in the winter and summer, respectively) and wild boar (Sus scrofa) (0.757 and 1.539 in winter and summer, respectively) were lower (Table 1).

The biomass of the three ungulate species calculated based on Random Encounter Model27 indicated that sika deer had the highest biomass densities (113.165 kg/km2 and 223.334 kg/km2 in the winter and summer, respectively) and the abundance proportions (45.02% and 41.31% in winter and summer, respectively). These were different from that calculated from the RAI values, that roe deer had the highest abundance proportions (59.87% and 56.93% in winter and summer, respectively) (Table 1). Based on biomass density, the seasonal abundance proportions of wild boar and sika deer were actually higher (Table 1).

[brobear]

Food habits:

We identified 11 prey species in the tiger scats, and 11 from the leopard scats (Table 2) in annually total. The prey compositions were significantly different (χ2 = 38.524, p < 0.01, Fisher’s exact test) between the tigers and the leopards. Wild boar, roe deer and sika deer were all the most common prey species for the tigers (73.97%) and the leopards (75.00%), and the three species significantly differed (χ2 = 26.254, p < 0.01, Fisher’s exact test) in the diets of the tigers and the leopards. Wild boar was most common in the tiger scats (36.64%). Roe deer was most common in the leopard scats (37.50%); but the second commonly preyed by the tigers (22.12%). Sika deer was the second most common prey item of the leopards (26.92%) (Table 2). Mid-size carnivores and small mammals were also consumed by both big cats (Table 2). The three ungulate species comprised 80.22% and 76.65% of overall biomass intake of the tigers and the leopards, respectively (Table 3). Wild boar contributed the greatest biomass for the tigers (45.88%) while sika deer, the largest consumed by leopards (33.71%) (Table 3).

Nine prey items were identified in the tiger diet and 11 items in the leopard diet in the summer (Table 2). In the winter, 11 and 7 items in the tiger and leopard diets, respectively (Table 2). Although Fisher’s exact test indicated a significant difference between the tiger and leopard diets in both winter (χ2 = 74.645, p < 0.01) and summer (χ2 = 27.474, p < 0.01), wild boar, roe deer and sika deer in combine provided the majority of biomass consumption in the summer (81.65% and 69.44% for the tigers and the leopards, respectively) and the winter (78.94% and 78.95% for the tigers and the leopards, respectively) (Tables 2 and 3). Nonetheless, the overall proportions of the prey species in the biomass consumptions by the tigers and the leopards differed significantly in the two seasons (χ2 = 14.586, p < 0.05 for the tigers and χ2 = 25.136, p < 0.01 for the leopards).

[brobear]

Prey selection:

The annual prey selection by Amur tiger showed a significant prey preference (p < 0.05) for wild boar based upon both RAI (Jacobs’ index = 0.562) and biomass (Jacobs’ index = 0.347) results (Table 4). The results from RAI and biomass, however, differed for sika deer and roe deer. Based on biomass, the tigers had a significant avoidance (p < 0.05) of sika deer, but no significance found according to RAI. For roe deer, RAI results showed the tigers had significant avoidance (Jacobs’ index = −0.537, p < 0.05), whereas biomass results indicated otherwise (Jacobs’ index = 0.090). Prey selections by the leopard also differed between RAI and biomass results. A significant avoidance (p < 0.05) for wild boar was revealed by the biomass result, but not shown such by the RAI results. Nonetheless, RAI results showed a preference of sika deer and avoidance of roe deer, but the biomass results showed an avoidance trend of sika deer, but a significant preference for roe deer (p < 0.05) (Table 4).

Seasonal variation in prey selection was also reflected in the results. Both RAI and biomass based results showed the tigers preferred wild boar in the winter and summer (p < 0.05) (Table 4). The RAI results showed that the tigers avoided roe deer in both seasons (p < 0.05), and avoided sika deer in the winter but preferred it in the summer (Table 4). The biomass results revealed that Amur tiger significantly avoided sika deer in both seasons; preferred roe deer in the summer, but avoided it in the winter (Table 4). In the summer, the Amur leopard did not show a significant preference or avoidance to the prey species (Table 4). In the winter, it preferred sika deer but avoided wild boar and roe deer according to the RAI results that differed somewhat from biomass based results.

[brobear]

Discussion:

Seasonal diets of Amur tigers and Amur leopards
Our dietary analysis revealed wild boar, sika deer and roe deer as the primary prey consumed by the tigers and the leopards with some seasonal variations. Our results were along with that found in Russian Far East20,24.

Wild boar and roe deer were the most common item consumed by tigers and leopards, respectively (Table 2). Wild boar was the principal prey species for tigers, with lower consumption in the summer comparing to that in the winter (Tables 2 and 3). The leopard diet had an opposite trend with higher occurrence frequency and biomass intake of wild boar in the summer than in the winter (Tables 2 and 3). We hypothesize that leopards avoid adult wild boar and prefer smaller individuals more available after spring birthing14,15. We speculate that the tigers may prefer to adult prey to maximize their energetic return15,17.

The frequency of occurrence and relative biomass contributions of roe deer and sika deer were varied in the tiger and leopard diets; the biomass contribution of sika deer in the leopard winter diet was the highest in China, similar to those found in Russia24, but the proportion of sika deer in China was lower (Table 3), probably due to the bizarre distribution of sika deer concentrated along the Sino-Russia6,28, Amur leopards in China relied more on roe deer than in Russia. The proportion of the smaller animals in the leopard winter diet was lower than in its summer diet, probably due to hibernation of both badger (Meles leucurus) and raccoon dog (Nyctereutes procyonoides) that may strengthen the predation on sika deer and roe deer during the winter. The prey diversity of the leopard was generally higher than that of the tiger20,24,29, but our results showed otherwise probably due to the small sample size of leopard scats.

Domestic animals had the smallest biomass proportion among the prey consumed by the Amur tigers and the Amur leopards. Our results showed that they consumed relatively more domestic animals in China than in Russian20,24 probably due to higher availability. Despite the small proportions, domestic animals are not ignorant component in the tiger and leopard diets in China, especially for the tigers in the winter. Due to the increased difficulty in tracking and hunting secluded prey in the winter, the tigers may inevitably turned to available domestic animals such as cattle28.

[brobear]

Prey selection:

Accurate estimation of prey density is of great importance30 in studying prey selection. In this study, RAI26 and biomass from the Random Encounter Model27 were utilized to estimate the densities of the three main prey species. The two methods showed different results in the density of roe deer (Table 1) that could affect the assessment of prey selection (Table 4). Our results showed that wild boar was the most preferred prey of the tigers, in accordance with Russia studies3,20,24,29. Both RAI and biomass based results directed that the tigers avoided sika deer and roe deer (Table 4). The preference of wild boar by the Amur tigers could be attributed to its large body weight12, shorter status and poorer mobility, especially when the ground is covered with snow in the winter; moreover, compared to deer, predation on wild boar confers higher energy profits to tiger. Considering that a tiger population cannot be maintained in the absence of the most abundant ungulate species, the avoidance of sika deer by tigers is puzzling12. The biomass result showed that the Amur leopard depended heavily on roe deer and avoided wild boar (Table 4). Our RAI results for prey selection by tigers and leopards correspond to those facts obtained in Russia3,20,24,29. However, the biomass result showed a higher use of roe deer by the leopards, though the biomass proportion of sika deer was relatively higher in the winter. A previous study suggested that the leopards primarily feed on small to medium-sized prey (10–40 kg)13. Due to its smaller size, selection on roe deer over sika deer is an appropriate strategy for the leopards (Tables 1 and 4). In addition, due to the along-border distribution of sika deer, a portion of leopard scats collected in the region where sika deer is absent, that may bias the of prey selection estimation of the leopards6,31.

In this study, the body weight of prey species was an important factor in estimating the food habits and prey selections of the predators. Average body weight was used to estimate the biomass contribution of prey in the diet of the Amur tiger and the leopard20,24, which may result in a higher estimation of wild boar, because of the difficulties in identification of the sex and age of the prey species from scat analysis. Based on kill data, Miller, et al.32 reported that Amur tiger preferred adult red deer (Cervus elaphus), sub-adult and juvenile wild boars. The prey density of prey species calculation through relative abundance would influence the estimation of prey selection by the tigers and the leopards. The estimation of prey density is affected by the speed, group size and age structure of the prey species. Therefore, we employed a Random Encounter Model, which considered moving speed and group size as parameters in the estimation. The accurate measures of average speed, however, is still a challenge. We used the daily average moving distance instead, which may result in some bias in density estimation.

 Our results strongly suggests that the body size of the prey species is an important factor in prey preference analysis for the tigers and the leopards. The diets differences between the felids indicate that resource partition enhance their coexistence.

[brobear]

*My personal observation; in this study comparing the food choices of Amur tigers and Amur leopards, bears are not mentioned. 
 

[brobear]

October Update: Amur Tiger Prey Study - October 2, 2020.
www.conservationfrontlines.org/2020/10/october-update-amur-tiger-prey-study/

In July, Conservation Frontlines introduced its first Select Study: research in support of predators, prey and rural communities in Russia’s vast and remote Far East. Only some 500 Amur (Siberian) tiger survive there, and they depend on wild boar and red deer. These two species are also vital for the food security and culture of the human community in the region.

With local people and Russian scientists, University of Montana grad student Scott Waller is studying the tiger’s prey species, developing innovative ways to analyze boar and deer populations with trail cameras. The goal is cost-effective, accurate, ecosystem-wide data for sustainable management to benefit tigers, deer, boar and, last but not least, people. His results will also apply to wildlife analysis across diverse species and habitats worldwide.

COVID-19 is affecting Scott’s work and funding. As we appeal for your help in covering his costs (including salaries for Russian field staff, equipment, repairs and supplies), we asked Scott to bring us up to date on his work:

Missoula, Montana, September 17—As summer comes to an end, autumn sets the hills along eastern Russia’s coastline ablaze in color and brings much needed respite from the bugs and humidity. Amur tigers blend in with the oranges and reds of the forest in the fall and the boar and deer forage for acorns and pine nuts in preparation for the coming winter. Field crews, taking advantage of this short window of good weather, are positioning our trail cameras in the Sikhote-Alin Nature Reserve. This will start the second season of our multi-year study—“Devising a Camera Trap Methodology for Estimated Abundance of Tiger Prey Species.”

The Russian arm of WCS, the Wildlife Conservation Society, is now also studying wild boar movement ecology, to come up with a better understanding of how wild boar travel in the Sikhote-Alin landscape. These Ussuri wild boar are something of a mystery—while European boar numbers are soaring, causing enormous crop damage and invading cities and towns, the population density of the Ussuri wild boar is low to begin with and seems to be declining.

What’s more, African Swine Fever, a serious disease that can devastate both domestic pigs and wild boar, has started to gain a foothold in the Russian Far East. This could have dire consequences not only for the boar, but also for the tigers that depend on them.

As our trail cameras are deployed, other field staff are working day and night to capture and radio-collar wild boar. These collars give us satellite fixes on boar locations every 15 minutes. Then, when snow falls, researchers will go out on skis to follow the paths of these collared boar, to correlate the GPS data with the actual movement of the animals.

Here in Montana, with my advisors I’ve begun to analyze preliminary data from these GPS collars to find the best way to determine wild boar daily movement rates. This parameter, movement rate, is a key to the equations of several of the methods I use to estimate prey population sizes. The movement rates must be accurate for us to derive accurate population figures. This in turn is vital to establishing science-based, sustainable practices and effective conservation actions to support the prey base of the Amur tiger.

But for the virus, I would be working in Sikhote-Alin now myself. The good news, I suppose, is that saving the travel costs stretches our budget. But we still need help to keep this study producing results. I appreciate your attention and assistance!

[brobear]

*My personal observation; in this study of Amur tiger prey, there is no mention of bears. 

[brobear]

A comparison of food habits and prey preference of Amur tiger (Panthera tigris altaica) at three sites in the Russian Far East

© 2015 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

pubmed.ncbi.nlm.nih.gov/25939758/

Abstract:
Prey availability is one of the principal drivers of tiger distribution and abundance. Therefore, formulating effective conservation strategies requires a clear understanding of tiger diet. We used scat analysis in combination with data on the abundance of several prey species to estimate Amur tiger diet and preference at 3 sites in the Russian Far East. We also examined the effect of pseudoreplication on estimates of tiger diet. We collected 770 scats across the 3 sites. Similar to previous studies, we found that tigers primarily preyed on medium to large ungulates, with wild boar, roe, sika and red deer collectively comprising 86.7% of total biomass consumed on average. According to Jacobs' index, tigers preferred wild boar, and avoided sika deer. Variation in preference indices derived from these scat analyses compared to indices derived from kill data appear to be due to adjustments in biomass intake when sex-age of a killed individual is known: a component missing from scat data. Pseudoreplication (multiple samples collected from a single kill site) also skewed results derived from scat analyses. Scat analysis still appears useful in providing insight into the diets of carnivores when the full spectrum of prey species needs to be identified, or when sample sizes from kill data are not sufficient. When sample sizes of kill data are large (as is now possible with GPS-collared animals), kill data adjusted by sex-age categories probably provides the most accurate estimates of prey biomass composition. Our results provide further confirmation of the centrality of medium ungulates, in particular wild boar, to Amur tiger diet, and suggest that the protection of this group of species is critical to Amur tiger conservation.

[brobear]

*My personal observation; in this study of Amur tiger prey preference; bears are not mentioned.

[brobear]

Wild Boar: 

[brobear]

*My personal observation; more adult male wild boar are killed by brown bears than by tigers.

A: There are more bears in the RFE than there are tigers.

B: Brown bears feed far more extensively on vegetation than on meat. Of the meat consumed by the brown bear, the majority comes from small mammals such as burrowing rodents and from carrion. As part-time predators, bears hunt and kill large prey far less often than do tigers.

*Conclusion: It appears that adult male wild boar are chosen by brown bears more frequently than by tigers.

[brobear]

Although Gotvansky repeatedly found remains of Himalayan black bears eaten by tigers, Anyuisky tigers, in spite of their size, do not seem to be prolific bear hunters. They most probably thrive on wild boars. In the summer of 2021, Gotvansky saw bears everywhere and all of them were in good condition. The reason was plenty of food.

For tigers, the situation was different. The reason was the National Park had only few wild pigs left (a result of a disease) and most of them were large males. Not an easy prey for any tiger. The Anyuisky male tigers, including the 4 monsters mentioned above, didn't respond by starting epic battles with monster male brown bears and monster male wild boars, but entered nordic long distance walking events. Many of them were away for long periods of time.

One thing is for sure. Anyuisky male tigers didn't grow into monsters by hunting monster brown bears and monster wild boars in times of need. Like most of us, they responded with budget cuts and trips to greener pastures.

Do tigers in Bolshekhtsirsky behave in a similar way as the monster tigers in Anyuisky when faced wih pressure? The answer is they don't. At least, females with cubs don't. That is to say, 'Zlata' didn't. In the 2022 winter, Gotvansky and inspector Lukin found prints of large wild boars. All of them were left by adults. The tigress, without her cubs, followed them. She killed one and waited for her cubs. The reports I read suggest her previous litter also made it to independance.

[brobear]

About the above post; breaking it down:

Quote: Although Gotvansky repeatedly found remains of Himalayan black bears eaten by tigers, Anyuisky tigers, in spite of their size, do not seem to be prolific bear hunters.

*Conclusion: The tigers occasionally would ambush small moon bears, but there is no such population of tigers as prolific bear hunters. Bears are always hunted by tigers as a last resort. The exception to the rule is when an individual large male tiger acquires a taste for bear flesh. This bear will then routinely stalk and ambush bears smaller than himself. 
______________________________________________________ 
 
Quote: They most probably thrive on wild boars. In the summer of 2021, Gotvansky saw bears everywhere and all of them were in good condition. The reason was plenty of food. 
 
*Conclusion: Evidently, plenty of vegetation and wild boars to provide for the numerous bears. With the bears being plentiful, this certainly proves that bear flesh is at the very bottom of the tiger's menu. 

[brobear]

Quote: For tigers, the situation was different. The reason was the National Park had only few wild pigs left (a result of a disease) and most of them were large males. Not an easy prey for any tiger.

*Conclusion: Large male wild boars is not the tiger's first choice when hunting the wild boar. Even when ambushed, which is the only way the tiger will make physical contact with an adult wild boar, the big hogs are not easy prey for the big cat.

Quote: The Anyuisky male tigers, including the 4 monsters mentioned above, didn't respond by starting epic battles with monster male brown bears and monster male wild boars, but entered nordic long distance walking events. Many of them were away for long periods of time.

*Conclusion: A tiger will prefer long-distance walking in their hunts, much preferring deer or younger pigs, than to risk ambushing the big boars or, with a certainty, bears. 
 
Quote: One thing is for sure. Anyuisky male tigers didn't grow into monsters by hunting monster brown bears and monster wild boars in times of need. Like most of us, they responded with budget cuts and trips to greener pastures.

[brobear]

Quote: Do tigers in Bolshekhtsirsky behave in a similar way as the monster tigers in Anyuisky when faced wih pressure? The answer is they don't. At least, females with cubs don't. That is to say, 'Zlata' didn't. In the 2022 winter, Gotvansky and inspector Lukin found prints of large wild boars. All of them were left by adults. The tigress, without her cubs, followed them. She killed one and waited for her cubs. The reports I read suggest her previous litter also made it to independance.

*Conclusion: Contrary to popular belief, the mother tigress as well as the mother she-bear can show more raw courage than the males of their perspective species.

[OldGreenGrolar]

/\ Any animals defending cubs will be more aggressive than usual. They are protecting another life other than their own.


Prey in the Russian Tiaga can be hard to find at certain seasons.

[brobear]

Bears chosen by tigers as potential prey:

1- sloth bear:
Sri Lankan sloth bear - sow: 128 pounds.
Sri Lankan sloth bear - boar: 165 pounds.
Indian sloth bear - sow: 165 pounds
Indian sloth bear - boar: 242 pounds.

2- Ussuri black bear: 
Asiatic black bear - sow: 157 pounds.

Asiatic black bear - boar: 270 pounds. 
Ussuri black bear - max: 440 pounds. 
 
3- Adolescent Ussuri brown bear: 300 pounds. 
4- Female Ussuri brown bear:  415 pounds. 
 
*Note: there is no confirmed case of a tiger ever ambushing a bear as heavy or heavier than himself.