Male reproductive input, breeding tenure, and turnover in high-density brown bear (Ursus arctos yesoensis) populations on the Shiretoko Peninsula, Hokkaido, Japan

Abstract

Male reproductive behavior has not been thoroughly investigated in large, non-social mammals. We studied male reproductive input using field observations and microsatellite DNA data for the brown bear (Ursus arctos yesoensis Lydekker, 1897) population in a special wildlife protection area on the Shiretoko Peninsula in Hokkaido, Japan. We identified the father of 82 offspring born between 2006 and 2018 from 54 litters produced by 20 females and revealed that they were sired by a total of 19 males. Overall, paternity was distributed relatively evenly among different males, although litter production tended to be skewed to a few bears in some years. Male breeding tenure varied among individuals, but most tenures were within the range of 1 to 6 years. Human-caused mortality, mostly occurring near human residential areas, induced male turnover, indicating that the special wildlife protection area located in the inner part of the Shiretoko Peninsula is not free from human impact. The frequency of successful reproduction was highest in 10- to 14-year-old bears, which is consistent with the period when males reach physical maturity. These results contribute to an understanding of breeding systems in large solitary mammals and to appropriate conservation and management strategies for brown bear populations.

Dining from the coast to the summit: Salmon and pine nuts determine the summer body condition of female brown bears on the Shiretoko Peninsula

“…This imbalance is mainly due to the fact that adult male bears, which migrate from different regions, are not accustomed to the presence of humans, and thus, male bears are more wary of humans. In addition, we previously identified individuals via genetic analysis of 118 scat samples (12 of them containing pine nuts) collected in the Rusha area (Shimozuru, Shirane, Jimbo, et al., 2020), of which 94 samples were identified as originating from either adult females or their dependent young. Based on this information, we consider the content of scat collected in the Rusha area to reflect the typical food habits of the 12 female brown bears targeted in this study.…”

Maternal human habituation enhances sons’ risk of human-caused mortality in a large carnivore, brown bears

“…S1). Group 3 comprised 13 very highly habituated bears that had been visually identified and frequently observed in this area from the late 1990s to 2018 28,[31][32][33] . Among them, six bears were captured and released with ear tags for radiotracking between 2013 and 2018 31 .…”

“…We also obtained: (1) hair samples collected from hair traps, including fence traps and tree-rub traps placed in several locations (including the Horobetsu-Iwaobetsu and Rusha areas) during 2010–2018; (2) skin tissues collected by biopsy dart sampling during 2011–2018; and (3) fecal samples collected during 2009–2018. The sampling methods have been detailed in our previous reports 30 – 32 , 34 . For bears captured or killed between 1998 and 2018, age was estimated by counting the dental cementum annuli 35 .…”

“…The parentage analysis was performed using a likelihood-based approach with CERVUS version 3.0.7 36 . The simulation parameters were 10,000 cycles, 150 candidate mothers and fathers per offspring, 40% of candidate parents sampled, and 1% of loci mistyped 32 . In the first step of the CERVUS analysis, we assigned a parent pair.…”

Reforestation provides a foraging habitat for brown bears (Ursus arctos) by increasing cicada Lyristes bihamatus density in the Shiretoko World Heritage site

“…The SWH has one of the highest densities of brown bears in the world (Shimozuru et al 2020a). In the study area, food items of the brown bears change across the seasons, depending on resource availability.…”