Abstract
Here we present annual nearest-neighbour distances (as a proxy of density) between females with cubs-of-the-year (hereafter FCOY) and reproductive characteristics of brown bears Ursus arctos in the Cantabrian Mountains (NW Spain), from 1989 to 2017. FCOY nearest-neighbour distances and reproduction parameters of 19 focal females followed over several consecutive years (from 2004 to 2017) were obtained from bears inhabiting the western sector of the Cantabrian Mountains, where most of the bear population resides. In contrast, general reproductive characteristics were studied in the whole Cantabrian Mountains (western and eastern sectors together) on a sample of 362 litter sizes and 695 cubs. Mean nearest-neighbour distance between FCOY was 2559 ± 1222 m (range = 1305–4757 m). Mean litter size was significantly larger in the west (1.8 ± 0.2 cubs) than in the east (1.3 ± 0.6 cubs). Mean litter size for the whole of the Cantabrian Mountains was 1.6 ± 0.3 cubs. Litter sizes of one, two and three cubs represented 33.4, 56.1 and 10.5% of observed family groups, respectively. Interannual variations in litter size were not significant for both the western and the eastern areas. Mean cub mortality was 0.2 ± 0.5 cubs and did not vary among years. Cub mortality per litter size was 3.9% for one cub, 69.2% for two cubs and 26.9% for three cubs. Mean reproductive rate of the 19 focal females was 1.5 ± 0.6 cubs (n = 58 litters). Litter size of focal FCOY did not differ from the litter size obtained from systematic observations in the whole Cantabrian Mountains. During this period, cub mortality occurred in 24.1% of the 58 litters. Females usually bred every second year (average litter interval = 2.2 years). The estimated reproductive rate for the bear population was 0.7 young born/year/reproductive adult female.
Highlights
The trend of an animal population depends on the interactions between the life-history characteristics of the species and local, external factors
No estimates exist for the density of females with cubs-of-theyear for the brown bear population that inhabits the Cantabrian Mountains (NW Spain), and only a few studies concerning reproductive characteristics have been conducted in the past (Wiegand et al 1998; Palomero et al 2007)
To gain deeper knowledge of this small and isolated bear population, we present here the annual nearestneighbour distance of FCOY and reproductive characteristics of brown bears in the Cantabrian Mountains calculated over a 28-year period
Summary
The trend of an animal population depends on the interactions between the life-history characteristics of the species (e.g. density, fecundity and survival) and local, external factors (e.g. availability of shelter, reproductive sites and food, and human density and distribution; Caughley 1977). Knowledge of such basic properties of a population is important for wildlife managers and has crucial implications for species conservation, and these factors may drive extinction risk (Brodie & Gibeau 2007). The long-term (> 25 years) data available for this study allows circumventing the main problem of research information obtained from small populations, which is typically limited to small sample sizes and, with subsequent management and conservation decisions based on sparse data sets
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