Asian black bears' smart strategy for seasonal energy balance

December 23, 2019

A collaboration led by scientists at Tokyo University of Agriculture and Technology (TUAT), Japan, has discovered that daily energy balance of Asian black bears (Ursus thibetanus) exhibited seasonal change with a twin-peak pattern: up in spring, down to the lowest point in summer, and up again in autumn. From spring to summer, the energy balance is surprisingly negative. Interestingly, bears obtain about 80% of the energy they need in a year by eating acorns in autumn.

Energy balance (i.e., energy intake minus energy usage) is an essential factor when evaluating an animal's nutritional state. "We aimed to identify periods of the year that are most important for Asian black bears in terms of energy balance," said the senior and corresponding author Dr Shinsuke Koike, associate professor at TUAT. "We estimated daily energy balance of 34 bears fitted with GPS collars in the central Japan as follows. Energy intake of bears was estimated using the energy content (kcal/g) of major food items, their average ingestion rate (g/min), and daily feeding time (min). Then, energy usage was calculated by an equation for the costs of resting, traveling, and feeding based on behavioral data monitored by the GPS collars."

Because food habits of bears change seasonally, each month scientists estimated the daily energy balance. Also, because bears change their feeding behavior depending on the availability of hard mast, they made separate estimations for years of good and poor mast conditions during autumn. The scientists then identified major food items from fecal analysis and calculated the gross energy content per unit for each item.

"We have been directly watching bears feeding over 10 years. And we measured ingestion rates of the major food items; acorns on the tree had the highest ingestion rate, while the values of other items did not show notable characteristics," said Koike. "We obsterved that the variability of energy expenditure rose moderately in good mast years, except for males. On the other hand, there was a twin-peak pattern of energy intake and energy balance, declining from May to July, rising again from August to October, and declining in November."

"Interstingly, only for females, the peak of energy intake and energy balance was larger in good mast years than in poor mast years, while the cumulative energy balance in good mast years was larger than in poor mast years for both females and males. After poor mast years, the cumulative energy balance of males become negative in February, during hibernation, and did not exceed zero until August, even if they could start feeding in May," Koike explains. "Thus, further longitudinal studies that examine cumulative energy balance, rather than energy balance alone, are necessary to clarify the seasonal change in the nutritional state of Asian black bears" adds Koike.
For information about the Koike laboratory, please visit

This research was supported by Grants- in-Aid for Scientific Research (Nos. 16H04932, 17H05971, 17H00797, 16H04939, and 19H02990) and the Pollution Control Research Fund from the Ministry of the Environment, Japan, funded this work.

About Tokyo University of Agriculture and Technology (TUAT):

TUAT is a distinguished university in Japan dedicated to science and technology. TUAT focuses on agriculture and engineering that form the foundation of industry, and promotes education and research fields that incorporate them. Boasting a history of over 140 years since our founding in 1874, TUAT continues to boldly take on new challenges and steadily promote fields. With high ethics, TUAT fulfills social responsibility in the capacity of transmitting science and technology information towards the construction of a sustainable society where both human beings and nature can thrive in a symbiotic relationship. For more information, please visit

Original publication:

Furusaka S, Tochigi K, Yamazaki K, Naganuma T, Inagaki A, Koike S.
Estimating the seasonal energy balance in Asian black bears and associated factors
Ecosphere, 10, e02891 (2019)


Shinsuke Koike, Associate professor, Laboratory of Forest Conservation Biology, Graduate School of Agriculture, TUAT, Japan

Tokyo University of Agriculture and Technology

Related Energy Articles from Brightsurf:

Energy System 2050: solutions for the energy transition
To contribute to global climate protection, Germany has to rapidly and comprehensively minimize the use of fossil energy sources and to transform the energy system accordingly.

Cellular energy audit reveals energy producers and consumers
Researchers at Gladstone Institutes have performed a massive and detailed cellular energy audit; they analyzed every gene in the human genome to identify those that drive energy production or energy consumption.

First measurement of electron energy distributions, could enable sustainable energy technologies
To answer a question crucial to technologies such as energy conversion, a team of researchers at the University of Michigan, Purdue University and the University of Liverpool in the UK have figured out a way to measure how many 'hot charge carriers' -- for example, electrons with extra energy -- are present in a metal nanostructure.

Mandatory building energy audits alone do not overcome barriers to energy efficiency
A pioneering law may be insufficient to incentivize significant energy use reductions in residential and office buildings, a new study finds.

Scientists: Estonia has the most energy efficient new nearly zero energy buildings
A recent study carried out by an international group of building scientists showed that Estonia is among the countries with the most energy efficient buildings in Europe.

Mapping the energy transport mechanism of chalcogenide perovskite for solar energy use
Researchers from Lehigh University have, for the first time, revealed first-hand knowledge about the fundamental energy carrier properties of chalcogenide perovskite CaZrSe3, important for potential solar energy use.

Harvesting energy from walking human body Lightweight smart materials-based energy harvester develop
A research team led by Professor Wei-Hsin Liao from the Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong (CUHK) has developed a lightweight smart materials-based energy harvester for scavenging energy from human motion, generating inexhaustible and sustainable power supply just from walking.

How much energy do we really need?
Two fundamental goals of humanity are to eradicate poverty and reduce climate change, and it is critical that the world knows whether achieving these goals will involve trade-offs.

New discipline proposed: Macro-energy systems -- the science of the energy transition
In a perspective published in Joule on Aug. 14, a group of researchers led by Stanford University propose a new academic discipline, 'macro-energy systems,' as the science of the energy transition.

How much energy storage costs must fall to reach renewable energy's full potential
The cost of energy storage will be critical in determining how much renewable energy can contribute to the decarbonization of electricity.

Read More: Energy News and Energy Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to