Variation in stable isotope ratios of carbon and nitrogen in Hokkaido sika deer Cervus nippon during 1990–2000: possible causes and implications for management

Abstract

Sika deer Cervus nippon populations in eastern Hokkaido, Japan, increased rapidly during 1990-1998. This increase appeared to have halted in 1999-2000, probably due to increased hunting and nuisance control. The period of rapid increase was associated with a disproportionately rapid increase in compensation paid for deer damage to crops. We studied changes in diet during 1990-2000, as reflected by stable isotope ratios of C and N in tooth collagen. We hypothesised that isotope ratios would demonstrate dietary shifts related to population levels and/or time, and that shifts in isotope ratios would be consistent with increasing individual consumption of pasture grasses at higher population levels. δ 13 C isotope ratios of tooth collagen in 3-year-old sika indicated a diet dominated by C3 plants throughout the period, and that forage species other than pasture grasses and dwarf bamboo Sasa nipponica (the main crop and woodland understory plants, respectively) were important elements. There was a significant decline in the δ 13 C isotope ratio during 1990-2000 in both males and females. δ 15 N values showed no trend with time for males, but increased over time in females. Indices of population (Sightings per Unit Effort, SPUE) were negatively correlated with female δ 13 C, and positively correlated with female δ 15 N, values, indicating a shift in diet over the period, especially among females. This shift may be related to population and/or offtake levels, in particular the rapid increase in female offtake for nuisance control and hunting during the period. The data are consistent with a relative increase in pasture grass consumption per individual at higher population levels; however, other explanations of the data are equally plausible. Possible dietary changes, and other factors, influencing the observed shift in isotope ratios are discussed. Although statistically significant, the magnitude of dietary shifts nevertheless appeared small, and did not provide evidence which would justify modifying the current policy, of limiting crop damage through managed population reduction to about 25% of peak levels.

Red deer bone and antler collagen are not isotopically equivalent in carbon and nitrogen

“…Carbon and nitrogen isotope signatures of bone and antler are now often used to reconstruct the ecological conditions in which ancient deer lived, to track past habitat changes in the vicinity of the sites of recovery, and to infer past human management practices . They are also used to define isotopic baselines with which human isotope signatures can be compared .…”

“…Carbon and nitrogen isotope signatures of bone and antler are now often used to reconstruct the ecological conditions in which ancient deer lived, to track past habitat changes in the vicinity of the sites of recovery, and to infer past human management practices. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] They are also used to define isotopic baselines with which human isotope signatures can be compared. [20,21] This is possible as herbivore proteinaceous body tissues predominantly reflect the isotopic composition of the plants (primarily that of the protein) consumed by the herbivore, potentially modulated by physiology and diet composition, [22][23][24][25][26][27][28][29][30][31] and there is isotopic variation in plants within and between ecosystems in both space and time due to physiological and environmental/climatic parameters.…”

Distinctive diet‐tissue isotopic discrimination factors derived from the exclusive bamboo‐eating giant panda

“…The leaves of the 2 bamboo species measured in this study had more negative δ 13 C values than the average for C3 plants as they are growing under a canopy. The results show similar δ 13 C and δ 15 N to the leaves of a dwarf bamboo (Halley et al 2006) and 2 herbaceous bamboo species (Pharus latifolius Linnaeus, 1759 and Streptochaeta sodiroana Hack, 1890) growing under the sun in growing house conditions (Silveira et al 1989).…”

Paleoecological reconstruction of Late Pleistocene deer from the Ryukyu Islands, Japan: Combined evidence of mesowear and stable isotope analyses

“…Quantitative analyses of feces of Hokkaido sika deer have shown that the deer were dependent on dwarf bamboo (Table 1), which had δ 13 C of −30.8 ± 0.40‰, being a significantly more negative value than that of other plants in the same habitat (− 29.7 ± 1.20‰) (Halley et al, 2006). This reflects a more prominent canopy effect on dwarf bamboo because it grows near the ground, covering the forest floor.…”