This comprehensive study examines bone remains from Niedźwiedzia Cave in the Eastern Sudetes, offering detailed insights into the palaeobiology and adversities encountered by the Pleistocene cave bear Ursus spelaeus ingressus in the Śnieżnik Massif. Emphasising habitual cave use for hibernation and a primarily herbivorous diet, the findings attribute mortality to resource scarcity during hibernation and habitat fragmentation amid climate shifts. Taphonomic analysis identifies prolonged cave use by successive generations without predation impact yet underscores alkaline cave conditions influencing post-depositional processes. Mortality patterns, notably among juveniles, imply dwindling resources, indicative of environmental instability. Skeletal examination reveals a high incidence of forelimb fractures, indicating risks during activities like digging or confrontations. Palaeopathological evidence unveils vulnerabilities to tuberculosis, abscesses, rickets, and injuries, elucidating mobility challenges. The cave’s silts exhibit an unusual zinc concentration, potentially derived from successive bear generations consuming zinc-rich plants. This study illuminates the lives of late cave bears, elucidating unique environmental hurdles faced near their species’ end.

(a) Palaeobiology and taphonomy

The study analysed 2122 cave bear cheek teeth from Niedźwiedzia Cave across seven areas, merging data from three nearby excavation sites for statistical analysis. Six areas underwent detailed examination following a comprehensive protocol (figure 2; Palaeobiology and taphonomy in electronic supplementary material, table S1). The analysis involved:

1. Anatomical and taxonomic identification, using statistical tests to detect biases and categorise teeth by developmental stages and distribution patterns.
2. Employing the minimum number of individuals (MNI) for individual categorisation.
3. Identifying bone damage caused by different factors, distinguishing between carnivore and human-induced alterations .
4. Utilising Stiner’s [36] age-scoring technique to determine the demographic structure of the bear assemblage. Using tooth eruption and wear, this technique identifies nine developmental stages that approximate true ages, resistant to damage and forming crucial foundational data for analysis.
5. Analysing mortality patterns through wear stages, survivor counts, age-specific mortality rates, and survival time curves across cave levels and areas.

The study combined tooth-based ontogenetic ages with postcranial estimates and employed various statistical analyses and software packages while controlling false discovery rates to ensure reliable results with a significance level below p < 0.05.

(b) Palaeopathology

The detailed analysis of approximately 2000 U. s. ingressus bones from Niedźwiedzia Cave, housed at the University of Wrocław (Poland), employed diverse methods (Palaeopathology in electronic supplementary material). This extensive study aimed to uncover an array of pathological changes shedding light on the bears’ adaptations to harsh environmental conditions. Additionally, it aids in comprehending the potential factors contributing to the eventual extinction of these bears in the Late Pleistocene.

(c) Geochemical analysis

Samples from different silt profiles in Marten’s and Primitive Man’s Corridors underwent thorough geochemical analysis, revealing specific sediment characteristics and elements present (figures 2, 3; Geochemical analysis in electronic supplementary material). These analyses involved assessing organic matter, carbon, nitrogen, sulphur, and phosphate content, as well as concentrations of various elements through specialised laboratory techniques.

(d) Bone material and collagen extraction

New isotopic analysis of cave bears from Niedźwiedzia Cave was compared with existing Central European data (Bone material and collagen extraction in electronic supplementary material, tables S2, S3). The study examined 39 adult remains—31 bones and 8 teeth—using collagen to understand their diet and tooth development, e.g. . Altitude-adjusted isotopic data from other caves were considered for comparison. Isotopic data underwent comparison using isotopic niche space analysis and the Kernel Utilisation Density (KUD) model, calculated at a 95% contour level with the rKIN package in R software. Collagen extraction involved a modified Longin method with NaOH treatment, followed by carbon and nitrogen measurements. Analysis at the University of Warsaw ensured precision below 0.1‰ for δ¹⁵N and below 0.2‰ for δ¹³C.

(e) Chronology

Chronological analysis of U. s. ingressus bones from Niedźwiedzia Cave involved radiocarbon and U–Th dating (Chronology in electronic supplementary material). Radiocarbon dating used collagen extracted from bones. U–Th dating at the U–series Laboratory in Warsaw included cleaning, collagen assessment, and alpha-spectrometric measurements to compute ages based on activity ratios, adjusting for initial thorium contamination.