Large carnivores (order Carnivora) are among the world's most threatened mammals due to a confluence of ecological and social forces that have unfolded over centuries. Combining specimens from natural history collections with documents from archival records, we reconstructed the factors surrounding the extinction of the California grizzly bear (Ursus arctos californicus), a once-abundant brown bear subspecies last seen in 1924. Historical documents portrayed California grizzlies as massive hypercarnivores that endangered public safety. Yet, morphological measurements on skulls and teeth generate smaller body size estimates in alignment with extant North American grizzly populations (approx. 200 kg). Stable isotope analysis (δ13C, δ15N) of pelts and bones (n = 57) revealed that grizzlies derived less than 10% of their nutrition from terrestrial animal sources and were therefore largely herbivorous for millennia prior to the first European arrival in this region in 1542. Later colonial land uses, beginning in 1769 with the Mission era, led grizzlies to moderately increase animal protein consumption (up to 26% of diet), but grizzlies still consumed far less livestock than otherwise claimed by contemporary accounts. We show how human activities can provoke short-term behavioural shifts, such as heightened levels of carnivory, that in turn can lead to exaggerated predation narratives and incentivize persecution, triggering rapid loss of an otherwise widespread and ecologically flexible animal.

Coupled social and ecological change drove the historical extinction of the California grizzly bear (Ursus arctos californicus)

Abstract Although the advent of high‐resolution GPS tracking technology has helped increase our understanding of individual and multispecies behavior in wildlife systems, detecting and recording direct interactions between free‐ranging animals remains difficult. In 2023, we deployed GPS collars equipped with proximity sensors (GPS proximity collars) on brown bears (Ursus arctos) and moose (Alces alces) as part of a multispecies interaction study in central Sweden. On 6 June, 2023, a collar on an adult female moose and a collar on an adult male bear triggered each other's UHF signal and started collecting fine‐scale GPS positioning data. The moose collar collected positions every 2 min for 89 min, and the bear collar collected positions every 1 min for 41 min. On 8 June, field personnel visited the site and found a female neonate moose carcass with clear indications of bear bite marks on the head and neck. During the predation event, the bear remained at the carcass while the moose moved back and forth, moving toward the carcass site about five times. The moose was observed via drone with two calves on 24 May and with only one remaining calf on 9 June. This case study describes, to the best of our knowledge, the first instance of a predation event between two free ranging, wild species recorded by GPS proximity collars. Both collars successfully triggered and switched to finer‐scaled GPS fix rates when the individuals were in close proximity, producing detailed movement data for both predator and prey during and after a predation event. We suggest that, combined with standard field methodology, GPS proximity collars placed on free‐ranging animals offer the ability for researchers to observe direct interactions between multiple individuals and species in the wild without the need for direct visual observation.

Proximity‐sensors on GPS collars reveal fine‐scale predator–prey behavior during a predation event: A case study from Scandinavia

While wildlife and cultural preservation goals can be either complimentary or counteractive, the goals of large carnivore conservation and traditional pastoralist lifestyles are often at odds. Livestock depredation can negatively impact the economies of livestock herders, while subsequent lethal removals contribute to local carnivore population declines. Here, we collaborated with two Sámi reindeer herding communities (2010–2016) situated in Sweden's boreal forest to evaluate the efficacy and economic feasibility of three brown bear predation mitigation measures: corralling pregnant reindeer during parturition, lethal bear management removals, and public bear-license hunting. Calving corrals increased survival for reindeer calves born to average-sized females by 7%–15%, and by 14%–30% for calves born to small females. However, the realized cost of implementing calving corrals outweighed the financial gain for both our study areas (net losses ranged between €1111 and €6210 per calf saved from bear predation per year when using the updated 2021 calf value; 1€ [Euro] = US$1.1), as well as for almost every theoretical scenario we explored (net losses €234 and €13,995 per calf saved from bear predation). The exception was the theoretical scenario where small herding communities overlapped large bear populations, which crossed the breakeven efficacy bear/reindeer ratio of 13.5 bears/100 reindeer and had a potential net gain of €36 per saved calf. Similarly, the cost of lethal management removals of bears outweighed the potential financial gain from saved calves, with net losses between €75 and €239 per calf. License hunting, where the hunters voluntarily incur the monetary costs of removing bears, is in most cases the only economically viable mitigation measure where the cost of mitigation did not outweigh the financial gain from increased reindeer survival. While the annual public license hunt was the most cost-effective mitigation measure, it may be less biologically effective, that is, bear hunting occurs in the fall and reindeer parturition the following spring which leaves time for the empty niche of harvested bears to be filled by survivors. Economically and biologically effective predation mitigation measures are key for promoting coexistence, and we suggest that potential mitigation measures should be studied in collaboration with local people. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/ecs2.4564

Large carnivore conservation and traditional pastoralism: A case study on bear–reindeer predation mitigation measures

Three-quarters of the planet’s land surface has been altered by humans, with consequences for animal ecology, movements and related ecosystem functioning. Species often occupy wide geographical ranges with contrasting human disturbance and environmental conditions, yet, limited data availability across species’ ranges has constrained our understanding of how human impact and resource availability jointly shape intraspecific variation of animal space use. Leveraging a unique dataset of 752 annual GPS movement trajectories from 370 brown bears (Ursus arctos) across the species’ range in Europe, we investigated the effects of human impact (i.e., human footprint index), resource availability, forest cover and disturbance, and area-based conservation measures on brown bear space use. We quantified space use at different spatio-temporal scales during the growing season (May - September): home range size; representing general space requirements, 10-day long-distance displacement distances, and routine 1-day displacement distances. We found large intraspecific variation in brown bear space use across all scales, which was profoundly affected by human footprint index, vegetation productivity, and recent forest disturbances creating opportunity for resource pulses. Bears occupied smaller home ranges and moved less in more anthropized landscapes and in areas of higher resource availability. Forest disturbances reduced space use while contiguous forest cover promoted longer daily movements. The amount of strictly protected and roadless areas within bear home ranges were too small to affect space use. Anthropized landscapes may hinder the expansion of small and isolated populations, such as the Apennine and Pyrenean, and obstruct population connectivity, for example between the Alpine or Carpathian with the Dinaric Pindos populations. Our findings call for actions to maintain bear movements across landscapes with high human footprint, for example by maintaining forest integrity, to support viable bear populations and their ecosystem functions.

Human footprint and forest disturbance reduce space use of brown bears (Ursus arctos) across Europe

Artikkelissa tarkastelemme suurpetojen ravintohoukutteluun perustuvan kaupallisen kuvaus- ja katselutoiminnan vaikutuksia poronhoitoon eteläisissä paliskunnissa. Poroelinkeino on korostanut kahden luontoperusteisen elinkeinon samanaikaisuuden ja -paikkaisuuden ongelmia ja haasteita. Tilanteen tarkastelua varten kehitämme yhteiskuntatieteellisen ja posthumanistisen ympäristötutkimuksen teoreettisiin keskusteluihin nojaten uutta monilajinen poronlaidun -käsitettä. Käsite toimii artikkelissamme työkaluna poronhoitoalueen luontokulttuurisen dynamiikan rakentumisen ja sen muutoksen tarkastelussa poronhoitoon kytkeytyvien käytäntöjen näkökulmasta.
Tutkimuksen keskeinen tulos on, että ravintohoukuttelun myötä petojen ja porojen muuttunut käyttäytyminen monilajisella poronlaitumella tuottaa monia haasteita poronhoidolle. Elinkeinon mahdollisuudet reagoida tilanteeseen rakentuvat osana itse alueeseen sekä sen luontoperustaisiin elinkeinoihin kohdistuvaa hallinnollista ja taloudellista sääntelyä, kulttuurisia ja sosiaalisia järjestyksiä sekä poronhoidon käytäntöjen kautta muodostuneita ympäristösuhteita. Kaupallisen karhukuvauksen hallintaan ja yhteiskunnallisiin velvoitteisiin kaivataan selkeyttä. Tutkimus perustuu Kuusamossa, Suomussalmella ja Taivalkoskella asuvien poronhoitajien kanssa kesällä ja syksyllä 2021 tehtyihin haastatteluihin.

Monilajinen poronlaidun ja suurpetojen ravintohoukuttelu

Brown bear predation on semi-domesticated reindeer and depredation compensations: Do the numbers add up?

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Large carnivore conservation and traditional pastoralism: A case study on bear–reindeer predation mitigation measures

Brown bear predation on semi-domesticated reindeer and depredation compensations: Do the numbers add up?