Owing to agricultural expansion worldwide, agricultural crops can have major effects on the life history traits of wildlife. However, the functional role of crop consumption on the life history traits of long-lived mammals is seldom evaluated quantitatively. Body size is an important life history trait because it is directly related to fitness. In this study, we investigated the functional role of long-term crop consumption on body growth of sika deer (Cervus nippon). Crop consumption accelerated body growth of not only the consumer but also the next generation, and its effect differed by sex. In females and males, the degree of crop consumption produced maximum differences of about 2 and 1 years in the ages at which 98% asymptotic size was attained, respectively. However, this difference did not always occur in males. The degree of crop consumption by mothers generated a maximum difference of about 15% in the hind-foot length of their fetus. This study revealed that the degree of long-term crop consumption affects the body growth of deer at an individual level, even within the same population. The crop consumption had a positive effect on the consumer and the next generation. Further examination of the effects of accelerated body growth on population growth rates will elucidate more accurately the effects of crop consumption on population dynamics in the landscape, including agricultural crop lands.

Robust estimates of demographic parameters are critical for effective wildlife conservation and management, but are difficult to obtain for elusive species. We estimated the breeding and adult population sizes, as well as the minimum population size, in a high-density brown bear population on the Shiretoko Peninsula, in Hokkaido, Japan, using DNA-based pedigree reconstruction. A total of 1,288 individuals, collected in and around the Shiretoko Peninsula between 1998 and 2020, were genotyped at 21 microsatellite loci. Among them, 499 individuals were identified by intensive genetic sampling conducted in two consecutive years (2019 and 2020) mainly by noninvasive methods (e.g., hair and fecal DNA). Among them, both parents were assigned for 330 bears, and either maternity or paternity was assigned to 47 and 76 individuals, respectively. The subsequent pedigree reconstruction indicated a range of breeding and adult (≥4 years old) population sizes: 128–173 for female breeders and 66–91 male breeders, and 155–200 for female adults and 84–109 male adults. The minimum population size was estimated to be 449 (252 females and 197 males) in 2019. Long-term continuous genetic sampling prior to a short-term intensive survey would enable parentage to be identified in a population with a high probability, thus enabling reliable estimates of breeding population size for elusive species.

Conflicts arising from the consumption of anthropogenic foods by wildlife are increasing worldwide. Conventional tools for evaluating the spatial distribution pattern of large terrestrial mammals that consume anthropogenic foods have various limitations, despite their importance in management to mitigate conflicts. In this study, we examined the spatial distribution pattern of crop-foraging sika deer by performing nitrogen stable isotope analyses of bone collagen. We evaluated whether crop-foraging deer lived closer to agricultural crop fields during the winter and spring, when crop production decreases. We found that female deer in proximity to agricultural crop fields during the winter and spring were more likely to be crop-foraging individuals. Furthermore, the likelihood of crop consumption by females decreased by half as the distance to agricultural crop fields increased to 10 km and fell to essentially zero at a distance of approximately 40 km. We did not detect a significant trend in the spatial distribution of crop-foraging male deer. The findings of spatial distribution patterns of crop-foraging female deer will be useful for the establishment of management areas, such as zonation, for efficient removal of them.