Dietary specialization depending on ecological context and sexual differences in Asiatic black bears

Autoři: Tomoki Mori aff001;  Saki Nakata aff002;  Shigeyuki Izumiyama aff003
Působiště autorů: Interdisciplinary Graduate School of Science and Technology, Shinshu University, Minamiminowa, Kamiina-gun, Nagano Prefecture, Japan aff001;  Graduate School of Science and Technology, Shinshu University, Minamiminowa, Kamiina-gun, Nagano Prefecture, Japan aff002;  Institute of Mountain Science, Shinshu University, Minamiminowa, Kamiina-gun, Nagano Prefecture, Japan aff003
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article


The food habits of the Asiatic black bear (Ursus thibetanus) are well studied, but there is a little evidence of dietary specialization—that is, when individuals use a narrower set of resources compared to the population as a whole. To examine the dietary composition at the individual level, seasonal patterns of dietary specialization, and sex-based dietary differences in Asiatic black bears, we attached Global Positioning System (GPS) collars to 15 Asiatic black bears and collected their scats in Nagano Prefecture, Japan from 2017 to 2018. Our results showed that the dietary composition differed among individuals, although seasonal changes in dietary composition were observed at the population level. Dietary specialization was high in summer (resources less abundant) and low in spring and autumn (resources more abundant), indicating a relationship with general food abundance and the dietary diversity of bears. In spring, all bears consumed green vegetation and/or seed of Fagaceae family from previous autumn; in early- and late- summer, dietary composition, such as green vegetation, insects, and fruits, greatly differed among individuals. In autumn, most bears heavily depended on seeds of Fagaceae which is high-quality food for bears.

Although we did not find statistical differences between sexes in terms of dietary specialization and diversity, we found variations in the timing of feeding on the Fagaceae family, being earlier in females compared with males. We also found considerable variation in dietary composition within sexes, suggesting that dietary specialization depends on multiple factors besides food abundance, food diversity, and sex.

Klíčová slova:

Autumn – Bears – Diet – Food – Fruits – Seeds – Shannon index – Spring


1. Bolnick DI, Svanbäck R, Fordyce JA, Yang LH, Davis JM, Hulsey CD, et al. The ecology of individuals: incidence and implications of individual specialization. Am Nat. 2002;161: 1–28. doi: 10.1086/343878 12650459

2. Svanbäck R, Bolnick DI. Intraspecific competition drives increased resource use diversity within a natural population. Proc Biol Sci. 2006;274: 839–844.

3. Svanbäck R, Bolnick DI. Intraspecific competition affects the strength of individual specialization: an optimal diet theory method. Evol Ecol Res. 2005;7: 993–1012

4. Araújo MS, Bolnick DI, Layman CA. The ecological causes of individual specialisation. Ecol Lett. 2011;14: 948–958. doi: 10.1111/j.1461-0248.2011.01662.x 21790933

5. Simpson SJ, Sibly RM, Lee KP, Behmer ST, Raubenheimer D. Optimal foraging when regulating intake of multiple nutrients. Anim Behav. 2004; 68: 1299–1311.

6. Machovsky-Capuska GE, Senior AM, Benn EC, Tait AH, Schuckard R, Stockin K, et al. Sex-specific macronutrient foraging strategies in a highly successful marine predator: the Australasian gannet. Mar Biol. 2016; 163: 75.

7. Ward AJ, Webster M, Hart PJ. Intraspecific food competition in fishes. Fish Fish. 2006; 7: 231–261.

8. Hashimoto Y, Takatsuki S. Food habits of Japanese black bear: a review. Honyurui Kagaku (Mamm Sci). 1997;37: 1–19.

9. Nozaki E, Azuma S, Aoi T, Torii H, Ito T, Maeda K. Food habits of Japanese black bear. International Conference on Bear Research and Management. 1983;5: 106–109.

10. Hashimoto Y. Seasonal food habits of the Asiatic black bear in the Chichibu Mountains, Japan. Mammal Study. 2002;27: 65–72

11. Koike S. Long-term trends in food habits of Asiatic black bears in the Misaka Mountains on the Pacific coast of central Japan. Mamm Biol. 2010;75: 17–28.

12. Mori T, Sugiura R, Kato M, Kato H, Niizuma Y. A seven-year longitudinal study on the food habits of the Asiatic black bear (Ursus thibetanus) in relation to mast production in Shirakawa Village, Gifu Prefecture, Japan. Mammal Study. 2018;43: 81–90.

13. Arimoto I, Goto Y, Nagai C, Furubayashi K. Autumn food habits and home-range elevations of Japanese black bears in relation to hard mast production in the beech family in Toyama Prefecture. Mammal Study. 2011;36: 199–209.

14. Koike S. Food habits and habitats. In: Tsubota T, Yamazaki K, editors. Bears in Japan: Biology of Hokkaido brown bears and Japanese black bears. University of Tokyo Press, Tokyo, Japan; 2011. pp. 88–102.

15. Hazumi T, Maruyama N, Mizuno A, Torii A, Maita K. Nutrient determination of Japanese black bear. In: Basic research on population dynamics of large wildlife and forest environment change. Nature conservation bureau of the Environment Agency, Tokyo, Japan; 1985.

16. Prefecture Gifu. Research report on population index of Japanese black bears. Gifu Prefecture, Gifu; 1995.

17. Larivière S. Ursus americanus. Mamm speci. 2001;647: 1–11.

18. Christiansen P. Evolutionary implications of bite mechanics and feeding ecology in bears. J Zool. 2007;272: 423–443.

19. Bartareau TM. Growth in body length of Florida black bears: Comparison of models. Florida Scientist. 2011;74: 168–180.

20. Hilderbrand GV, Schwartz CC, Robbins CT, Hanley TA. Effect of hibernation and reproductive status on body mass and condition of coastal brown bears. J Wildl Manage. 2000;64: 178–183.

21. Japan Meteorological Agency. Japan Meteoroligical Agency, Tokyo, Japan; 2000–2018 [cited 4 March 2019]. Database: figshare [Internet]. Available from:

22. QGIS. Development. 2018. QGIS Geographic Information System. Open source Geospatial Foundation. Available from:

23. Oi T. The Japanese black bear: Biology of bears in forest ecosystems. 1st ed. Tokyo: Tokai University Press; 2009.

24. Kozakai C, Yamazaki K, Nemoto Y, Nakajima A, Umemura Y, Koike S, et al. Fluctuation of daily activity time budgets of Japanese black bears: relationship to sex, reproductive status, and hard-mast availability. J Mammal. 2013;94: 351–360.

25. Herrero S, Hamer D. Courtship and copulation of a pair of grizzly bears, with comments on reproductive plasticity and strategy. J Mammal. 1977;58: 441–444.

26. Koike S, Masaki T, Nemoto Y, Kozakai C, Yamazaki K, et al. Estimate of the seed shadow created by the Asiatic black bear Ursus thibetanus and its characteristics as a seed disperser in Japanese cool-temperate forest. Oikos. 2011;120: 280–290.

27. Mattson DJ, Blanchard BM, Knight RR. Food habits of Yellowstone grizzly bears, 1977–1987. Can J Zool. 1991;69: 1619–1629.28.

28. Mealey SP. The natural food habits of grizzly bears in Yellowstone National Park, 1973–1974. International Conference on Bear Research and Management. 1980;4: 281–292.

29. Sato Y, Mano T, Takatsuki S. Applicability of the point-frame method for quantitative evaluation of bear diet. Wildl Soc Bull. 2000;311–316.

30. Bolnick DI, Yang LH, Fordyce JA, Davis JM, Svanbäck R. Measuring individual-level resource specialization. Ecology. 2002;83: 2936–2941.

31. Burnham KP, Anderson DR. Model selection and multimodel inference: a practical information-theoretic approach. Springer Science&Business Media: New York Press; 2003.

32. Bates D. lme4: linear mixed-effects models using S4 classes. R package version 0.99875–9. 2007.

33. R Core Team. R: A Language and Environment for Statistical Computing. 2018. R Foundation for Statistical Computing, Vienna, Austria. Available from:

34. Thiemann GW, Iverson SJ, Stirling I, Obbard ME. Individual patterns of prey selection and dietary specialization in an Arctic marine carnivore. Oikos. 2011;120: 1469–1478.

35. Murray MH, Fassina S, Hopkins JB III, Whittington J, Clair CCS. Seasonal and individual variation in the use of rail-associated food attractants by grizzly bears (Ursus arctos) in a national park. PLoS One. 2017;12: e0175658. doi: 10.1371/journal.pone.0175658 28542218

36. Lesmerises R, Rebouillat L, Dussault C, St-Laurent MH. Linking GPS telemetry surveys and scat analyses helps explain variability in black bear foraging strategies. PLoS One. 2015;10: e0129857. doi: 10.1371/journal.pone.0129857 26132204

37. Tinker MT, Bentall G, Estes JA. Food limitation leads to behavioral diversification and dietary specialization in sea otters. Proc Natl Acad Sci U S A. 2008; 105:560–565 doi: 10.1073/pnas.0709263105 18195370

38. Furusaka S, Kozakai C, Nemoto Y, Umemura Y, Naganuma T, Yamazaki K, Koike S. The selection by the Asiatic black bear (Ursus thibetanus) of spring plant food items according to their nutritional values. ZooKeys. 2017;672: 121–133.

39. Costa‐Pereira R, Tavares LE, de Camargo PB, Araújo MS. Seasonal population and individual niche dynamics in a tetra fish in the Pantanal wetlands. Biotropica. 2017;49: 531–538.

40. Erlenbach JA, Rode KD, Raubenheimer D, Robbins CT. Macronutrient optimization and energy maximization determine diets of brown bears. J Mammal. 2014; 95: 160–168.

41. Takahashi K, Shiota T, Tamatani H, Koyama M, Washitani I. Seasonal variation in fleshy fruit use and seed dispersal by the Japanese black bear (Ursus thibetanus japonicus). Ecol Res. 2008;23: 471–478.

42. Koike S. Fruiting phenology and its effect on fruit feeding behavior of Asiatic black bears. Mammal Study. 2009;34: 47–53.

43. Nelson RA, Folk GE Jr, Pfeiffer EW, Craighead JJ, Jonkel CJ, Steiger DL. Behavior, biochemistry, and hibernation in black, grizzly, and polar bears. Ursus. 1983;5: 284–290.

44. Masaki T, Takahashi K, Sawa A, Kado T, Naoe S, Koike S, et al. Fleshy fruit characteristics in a temperate deciduous forest of Japan: how unique are they? J Plant Res. 2012;125: 103–114. doi: 10.1007/s10265-011-0423-0 21533625

45. Nakajima A, Koike S, Yamazaki K, Kozakai C, Nemoto Y, Masaki T, et al. Feeding habits of Asian black bears (Ursus thibetanus) in relation to the abundance and timing of fruiting in 13 tree species. Mammal Study. 2018;43: 167–179.

46. Tietje WD, Ruff RL. Denning behavior of black bears in boreal forest of Alberta. J Wildl Manage. 1980;44: 858–870.

47. Haroldson MA, Ternent MA, Gunther KA, Schwartz CC. Grizzly bear denning chronology and movements in the Greater Yellowstone Ecosystem. Ursus. 2002;13: 29–37.

48. Yamamoto T, Tamatani H, Tanaka J, Oshima G, Mura S, Koyama, M. Abiotic and biotic factors affecting the denning behaviors in Asiatic black bears Ursus thibetanus. J Mammal. 2015;97: 128–134.

49. Swenson JE, Adamič M, Huber D, Stokke S. Brown bear body mass and growth in northern and southern Europe. Oecologia. 2007;153: 37–47. doi: 10.1007/s00442-007-0715-1 17415593

50. Hashimoto Y, Kaji M, Sawada H, Takatsuki S. Five-year study on the autumn food habits of the Asiatic black bear in relation to nut production. Ecol Res. 2003;18: 485–492.

Článek vyšel v časopise


2019 Číslo 10
Nejčtenější tento týden