Fourth paper-Locally adapted diets help explain the last days of the cave bear in South-Eastern Europe

New research from ERIS (“Emil Racoviță” Institute of Speleology, Romanian Academy of Science) and IPHES-CERCA (Institut Català de Paleoecologia Humana i Evolució Social) reveals that cave bears adapted their diets to the specific conditions of their immediate landscapes, showing marked local dietary endemism; but this very specialisation may have made them more vulnerable to climate and environmental change during the Late Pleistocene, contributing to their extinction.

The work, led by Paulo Duñó-Iglesias (IPHES-CERCA) and supervised by Dr. Florent Rivals (ICREA, IPHES-CERCA), Dr. Iván Ramírez-Pedraza (IPHES-CERCA), and Dr. Marius Robu (ERIS), was carried out in collaboration with an international team of 18 researchers from Spain, Romania, Moldova, Bulgaria, and Serbia.

The findings, published [Open Access] in Palaeogeography, Palaeoclimatology, Palaeoecology, provide new insights into the extinction of the cave bear (Ursus spelaeus) in South-Eastern Europe during the Late Pleistocene. The study represents the largest dental microwear analysis ever conducted on cave bears as well as brown bears (U. arctos), examining 316 specimens from 20 Late Pleistocene palaeontological sites across the Romanian Carpathians, Moldavian Plateau, Western and Central Balkans, and the Western Rhodopes.

The paper can be downloaded here:

https://www.sciencedirect.com/science/article/pii/S0031018225004857

Teeth as a “window” into the last days of the cave bears

Dental microwear analysis examines microscopic features on tooth enamel caused by chewing different types of food. These marks record the diet in the last days or weeks before death, offering a short-term, high-resolution perspective that complements other methods such as stable isotope analysis. Many of the studied bears likely died during hibernation in karstic caves, leaving exceptionally well-preserved evidence of their seasonal diets during a critical period for survival, the pre-hibernation phase.

Not just strict herbivores

Traditionally, cave bears have been considered specialised herbivores. However, the new microwear results show that their diets varied greatly between regions and often resembled those of modern omnivorous bears in the northern hemisphere, such as the brown bear U. arctos.

Competition with co-existing brown bears?

In some sites, such as Trinca (Moldova), cave bears and brown bears (U. arctos) lived side-by-side. Microwear patterns there suggest niche partitioning – a division of food resources – during the critical pre-hibernation “hyperphagic” period when bears must build fat reserves for winter. However, when microwear patterns are compared at a broader, regional scale, they indicate a degree of niche overlap between the two species. This overlap may have further disadvantaged cave bears, as they faced competition from the more generalist and smaller-bodied (and therefore more efficient) brown bears.

Chronology of the last survivors?

Radiocarbon dating of 16 specimens places the youngest U. spelaeus in the region at around 35,000 years ago (Butești, Moldova), shortly before the species disappeared from Europe. This period coincided with abrupt climatic shifts and increased ecological stress.

Why local adaptation was not enough?

The study concludes that cave bears showed local dietary flexibility, adapting to the specific resources of each region, rather than a generalist survival strategy. This “dietary endemism” may have left them vulnerable when climate change altered landscapes rapidly during MIS 3. Seasonal food shortages, the high energy demands of hibernation, and possible brown bear and human competition for caves likely contributed to a gradual, multifactorial extinction.

A step forward in understanding megafaunal extinction

“These results challenge the long-standing view of cave bears as having a homogeneous, strictly herbivorous diet, showing instead that their feeding strategies could vary according to local conditions,” explains lead author Paulo Duñó-Iglesias. “They could adapt, but their survival strategies were deeply tied to — and over generations became highly dependent on — the specific conditions and resources of their local environment. When that environment changed too drastically, the specific resources they relied on diminished or disappeared, and their ability to survive collapsed.”

The authors stress the importance of combining microwear evidence with isotopic and morphological data to better understand ecology and extinction processes in Pleistocene megafauna.

Full reference (OPEN ACCES):

Duñó-Iglesias, P., Ramírez-Pedraza, I., Rivals, F., Mirea, I.-C., Faur, L.-M., Vlaicu, M., Obadă, T., Croitor, R., Pascari, V., Delinschi, E., Hristova, L., Spassov, N., Gospodinov, M., Dimitrijević, V., Alaburić, S., Bogićević, K., Stefanović, I., Robu, M., 2025. Dental microwear of cave bear (Ursus spelaeus) reveals locally adapted foraging strategies in South-Eastern Europe during late MIS 3. Palaeogeogr. Palaeoclimatol. Palaeoecol. 113200. https://doi.org/10.1016/j.palaeo.2025.113200