DNA from scats combined with capture–recapture modeling: a promising tool for estimating the density of red foxes—a pilot study in a boreal forest in southeast Norway
In spite of its important role as predator of small game species, estimating the density of red fox Vulpes vulpes has been hampered by the species’ highly variable ranging pattern and elusive behavior. DNA analysis from scats combined with spatially explicit capture–recapture (SECR) modeling might remedy this. In a 50-km2 coniferous forest in southeast Norway, we collected scats on logging roads in late winter. DNA was extracted, amplified, and genotyped using 11 microsatellite markers. Of 184 samples collected, 126 were genotyped successfully, of which 46 (36.5%) produced individual genetic profiles. Twenty-five of these were different individuals: 13 females and 12 males. Nine of them were identified in multiple scats; mean recapture rate among all was 1.8/animal. Applying a conventional capture–recapture model (CAPWIRE) to the genotyped samples, 36 (95% CI 26–52) different individuals were estimated to have been present in the area during the sampling period. For estimating population density, we constructed three differently sized occupancy areas based on distances between recaptures, viz. ½ and 1/1 mean maximum distance moved (MMDM) and the local convex hull home range method (LoCoH). Areas varied from 60 km2 (½MMDM) to 112 km2 (MMDM), producing density estimates of 0.60 and 0.32 foxes/km2, respectively; the 95% LoCoH range method produced an estimate of 0.44 animals/km2. Based on SECR modeling, the density was estimated at 0.38 (95% CI 0.21–0.70) animals/km2. Smaller confidence intervals are expected with more appropriate sampling design than used in this pilot study.
KeywordsDensity estimation Genetic sampling Meso-predator Scatology Red fox SECR analysis
We thank the laboratory staff of The Norwegian Institute of Bioeconomy Research (NIBIO) at Svanhovd for conducting the genetic analysis of the scats.
The central office of NIBIO at Ås funded the study.
- Efford M (2018) Spatially Explicit Capture-Recapture, Version 3.17 (in R)Google Scholar
- Getz WM, Fortmann-Roe S, Cross PC, Lyons AJ, Ryan SJ, Wilmers CC (2007) LoCoH: nonparametric kernel methods for constructing home ranges and utilization distributions. PLoS One. https://doi.org/10.1371/journal.pone.00di00207
- Kery M, Gardner B, Stoeckle T, Weber D, Royle JA (2011) Use of spatial capture-recapture modeling and DNA data to estimate densities of elusive animals. Conserv Biol 25:356–364Google Scholar
- Lindström, ER (1982) Population ecology of the red fox (Vulpes vulpes L.) in relation to food supply. PhD dissertation, University StockholmGoogle Scholar
- Lindström ER (1989) Food limitation and social regulation in a red fox population. Holarct Ecol 12:70–79Google Scholar
- Maffei L, Noss AJ (2008) How small is too small? Camera trap survey areas and density estimates for ocelots in the Bolivian Chaco. Biotropica 40:71–75Google Scholar
- Manivannan A (2013) Population genetic analysis of red foxes (Vulpes vulpes) in Hedmark County, Norway—a pilot study. MSc thesis, Hedmark University College, NorwayGoogle Scholar
- Panasci M, Ballard WB, Breck SW, Rodriguez D, Densmore LD, Western DB, Baker RJ (2011) Evaluation of fecal DNA preservation techniques and effects of sample age and diet on genotyping success. USDA National Wildlife Research Center, Staff Publication 1301Google Scholar
- Santini A, Luccini V, Fabbri E, Randi E (2007) Ageing and environmental factors affect PCR success in wolf (Canis lupus) excremental DNA samples. Mol Ecol Notes 7:955–961Google Scholar
- Thapa K, Shrestha R, Karki J, Thapa GJ, Subedi N, Pradhan NMB, Dhakal M, Khanal P, Kelly MJ (2014) Leopard Panthera pardus fusca density in the seasonally dry, subtropical forest in the Bhabhar of Terai Arc, Nepal. Adv Ecol, Article ID 286949, 12 pages. https://doi.org/10.1155/2014/28694
- Travaini A, Laffitte R, Delibes M (1996) Determining the relative abundance of European red foxes by scent-station methodology. Wildl Soc Bull 24:500–504Google Scholar
- Vynne C, Baker MR, Breuer ZK, Wasser SK (2012) Factors influencing degradation of DNA and hormones in maned wolf scat. Anim Cons https://doi.org/10.1111/j1469-1795.2011.00503.x