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<p>Long-term monitoring of threatened carnivores provides rare insight into how environmental change shapes population dynamics. We analyzed 27 years (1997–2023) of standardized visual observations from the Golestanak Core Zone, a high-altitude, strictly protected area within the Central Alborz Protected Area (CAPA) in northern Iran, which represents one of the most reproductively active habitats for the Syrian brown bear (<i>Ursus arctos syriacus</i>). Intensive daily ranger patrols during the snow-free season enabled reliable detection of solitary bears, females with cubs, and cubs, allowing robust quantification of population trends and reproductive output. Population indices were assessed in the Golestanak Core Zone using the Bear Litter Size Index (BLSi) and Bear Sighting Rate Index (BSRi), while habitat and environmental predictors, including land cover, NDVI, and seasonal weather variables, were derived from MODIS products and local synoptic stations and aggregated at the CAPA landscape scale. We combined linear regression with generalized linear models (GLMs) to link key environmental drivers to population indices, carefully selecting and validating models to ensure robust and ecologically meaningful inference. BSRi revealed contrasting trends: solitary bears increased markedly, females with cubs declined slightly, and cubs exhibited a weak positive trajectory, all with substantial interannual variability. BLSi rose overall from ~1.25 to 1.70 cubs per female, despite yearly fluctuations. GLM results indicated that BSRi and BLSi were strongly influenced by seasonal vegetation and human-modified landscapes. For both indices, higher NDVI in winter was consistently associated with lower values, whereas urban and built-up areas positively affected BSRi and BLSi. Other variables, including forest type and seasonal climate, had weaker and model-dependent effects. In the absence of long-term datasets and studies, this research provides one of the most extensive assessments of brown bear population fluctuations under a complex set of environmental variables in a high-elevation, human-influenced ecosystem, offering valuable insights for designing effective conservation strategies to support this threatened subspecies in today’s rapidly changing world.</p>

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Divergent Temporal Trends in Brown Bear Survival and Reproductive Indices Shaped By Seasonal Vegetation Dynamics and Urban Expansion

  • 期刊论文

  • 发表日期：

    2026年7月23日

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  • Farid Salmanpour,
  • Zahra Shakoori,
  • Mehdi Tizrouyan,
  • Mahan Salmanpour,
  • Sanaz Nouri,
  • Mehdi Kia,
  • Rahman Eshaghi,
  • Alireza Ebrahimi

摘要

Long-term monitoring of threatened carnivores provides rare insight into how environmental change shapes population dynamics. We analyzed 27 years (1997–2023) of standardized visual observations from the Golestanak Core Zone, a high-altitude, strictly protected area within the Central Alborz Protected Area (CAPA) in northern Iran, which represents one of the most reproductively active habitats for the Syrian brown bear (Ursus arctos syriacus). Intensive daily ranger patrols during the snow-free season enabled reliable detection of solitary bears, females with cubs, and cubs, allowing robust quantification of population trends and reproductive output. Population indices were assessed in the Golestanak Core Zone using the Bear Litter Size Index (BLSi) and Bear Sighting Rate Index (BSRi), while habitat and environmental predictors, including land cover, NDVI, and seasonal weather variables, were derived from MODIS products and local synoptic stations and aggregated at the CAPA landscape scale. We combined linear regression with generalized linear models (GLMs) to link key environmental drivers to population indices, carefully selecting and validating models to ensure robust and ecologically meaningful inference. BSRi revealed contrasting trends: solitary bears increased markedly, females with cubs declined slightly, and cubs exhibited a weak positive trajectory, all with substantial interannual variability. BLSi rose overall from ~1.25 to 1.70 cubs per female, despite yearly fluctuations. GLM results indicated that BSRi and BLSi were strongly influenced by seasonal vegetation and human-modified landscapes. For both indices, higher NDVI in winter was consistently associated with lower values, whereas urban and built-up areas positively affected BSRi and BLSi. Other variables, including forest type and seasonal climate, had weaker and model-dependent effects. In the absence of long-term datasets and studies, this research provides one of the most extensive assessments of brown bear population fluctuations under a complex set of environmental variables in a high-elevation, human-influenced ecosystem, offering valuable insights for designing effective conservation strategies to support this threatened subspecies in today’s rapidly changing world.