Estimating macropod grazing density and defining activity patterns using camera-trap image analysis
Helen R. Morgan A B C D , Guy Ballard A B C , Peter J. S. Fleming A B C , Nick Reid A , Remy Van der Ven B and Karl Vernes A
+ Author Affiliations
- Author Affiliations
A Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia.
B Vertebrate Pest Research Unit, New South Wales Department of Primary Industries, University of New England, Armidale, NSW 2351, Australia.
C Vertebrate Pest Research Unit, New South Wales Department of Primary Industries, Orange Agricultural Institute, Orange, NSW 2800, Australia.
D Corresponding author. Email: millybrook@gmail.com
Wildlife Research 45(8) 706-717 https://doi.org/10.1071/WR17162
Submitted: 13 November 2017 Accepted: 15 October 2018 Published: 10 December 2018
Abstract
Context: When measuring grazing impacts of vertebrates, the density of animals and time spent foraging are important. Traditionally, dung pellet counts are used to index macropod grazing density, and a direct relationship between herbivore density and foraging impact is assumed. However, rarely are pellet deposition rates measured or compared with camera-trap indices.
Aims: The aims were to pilot an efficient and reliable camera-trapping method for monitoring macropod grazing density and activity patterns, and to contrast pellet counts with macropod counts from camera trapping, for estimating macropod grazing density.
Methods: Camera traps were deployed on stratified plots in a fenced enclosure containing a captive macropod population and the experiment was repeated in the same season in the following year after population reduction. Camera-based macropod counts were compared with pellet counts and pellet deposition rates were estimated using both datasets. Macropod frequency was estimated, activity patterns developed, and the variability between resting and grazing plots and the two estimates of macropod density was investigated.
Key Results: Camera-trap grazing density indices initially correlated well with pellet count indices (r2 = 0.86), but were less reliable between years. Site stratification enabled a significant relationship to be identified between camera-trap counts and pellet counts in grazing plots. Camera-trap indices were consistent for estimating grazing density in both surveys but were not useful for estimating absolute abundance in this study.
Conclusions: Camera trapping was efficient and reliable for estimating macropod activity patterns. Although significant, the relationship between pellet count indices and macropod grazing density based on camera-trapping indices was not strong; this was due to variability in macropod pellet deposition rates over different years. Time-lapse camera imagery has potential for simultaneously assessing herbivore foraging activity budgets with grazing densities and vegetation change. Further work is required to refine the use of camera-trapping indices for estimation of absolute abundance.
Implications: Time-lapse camera trapping and site-stratified sampling allow concurrent assessment of grazing density and grazing behaviour at plot and landscape scale.
Additional keywords: kangaroo behaviour, dung pellet counts, pellet deposition, time-lapse.
References
Antos, M. J., and Yuen, K. (2014). Camera trap monitoring for inventory management effectiveness in Victorian National Parks: tailoring approaches to suit specific questions. In ‘Camera Trapping: Wildlife Management and Research’. (Eds P. Meek, P. Fleming, G. Ballard, P. Banks, A. Claridge, J. Sanderson and D. Swann.) (pp. 13–23.) (CSIRO Publishing: Collingwood)Australian Government Bureau of Meteorology (BOM) (2017). Climate Data Online. [Data set] Available at http://www.bom.gov.au/climate/data/ [Accessed 18 October 2017]
Banks, P. B. (2001). Predation-sensitive grouping and habitat use by eastern grey kangaroos: a field experiment. Animal Behaviour 61, 1013–1021.
| Predation-sensitive grouping and habitat use by eastern grey kangaroos: a field experiment.Crossref | GoogleScholarGoogle Scholar |
Bengsen, A., Butler, J., and Masters, P. (2011a). Estimating and indexing feral cat population abundances using camera traps. Wildlife Research 38, 732–739.
| Estimating and indexing feral cat population abundances using camera traps.Crossref | GoogleScholarGoogle Scholar |
Bengsen, A. J., Leung, L. K. P., Lapidge, S. J., and Gordon, I. J. (2011b). Using a general index approach to analyze camera‐trap abundance indices. The Journal of Wildlife Management 75, 1222–1227.
| Using a general index approach to analyze camera‐trap abundance indices.Crossref | GoogleScholarGoogle Scholar |
Bulinski, J., and McArthur, C. (2000). Observer error in counts of macropod scats. Wildlife Research 27, 277–282.
| Observer error in counts of macropod scats.Crossref | GoogleScholarGoogle Scholar |
Cairns, S., Lollback, G., and Payne, N. (2008). Design of aerial surveys for population estimation and the management of macropods in the Northern Tablelands of New South Wales, Australia. Wildlife Research 35, 331–339.
| Design of aerial surveys for population estimation and the management of macropods in the Northern Tablelands of New South Wales, Australia.Crossref | GoogleScholarGoogle Scholar |
Caughley, G. (1964). Social organization and daily activity of the red kangaroo and the grey kangaroo. Journal of Mammalogy 45, 429–436.
| Social organization and daily activity of the red kangaroo and the grey kangaroo.Crossref | GoogleScholarGoogle Scholar |
Caughley, J., Bayliss, P., and Giles, J. (1984). Trends in kangaroo numbers in Western New South Wales and their relation to rainfall. Wildlife Research 11, 415–422.
| Trends in kangaroo numbers in Western New South Wales and their relation to rainfall.Crossref | GoogleScholarGoogle Scholar |
Colagross, A. M. L., and Cockburn, A. (1993). Vigilance and grouping in the eastern grey kangaroo, Macropus giganteus. Australian Journal of Zoology 41, 325–334.
| Vigilance and grouping in the eastern grey kangaroo, Macropus giganteus.Crossref | GoogleScholarGoogle Scholar |
Coulson, G. (2009). Behavioural ecology of red and grey kangaroos: Caughley’s insights into individuals, associations and dispersion. Wildlife Research 36, 57–69.
| Behavioural ecology of red and grey kangaroos: Caughley’s insights into individuals, associations and dispersion.Crossref | GoogleScholarGoogle Scholar |
Coulson, G. M., and Raines, J. A. (1985). Methods for small-scale surveys of grey kangaroo populations. Wildlife Research 12, 119–125.
| Methods for small-scale surveys of grey kangaroo populations.Crossref | GoogleScholarGoogle Scholar |
Coulson, G., Cripps, J. K., and Wilson, M. E. (2014). Hopping down the main street: eastern grey kangaroos at home in an urban matrix. Animals (Basel) 4, 272–291.
| Hopping down the main street: eastern grey kangaroos at home in an urban matrix.Crossref | GoogleScholarGoogle Scholar |
Cusack, J. J., Swanson, A., Coulson, T., Packer, C., Carbone, C., Dickman, A. J., Kosmala, M., Lintott, C., and Rowcliffe, J. M. (2015). Applying a random encounter model to estimate lion density from camera traps in Serengeti National Park, Tanzania. The Journal of Wildlife Management 79, 1014–1021.
| Applying a random encounter model to estimate lion density from camera traps in Serengeti National Park, Tanzania.Crossref | GoogleScholarGoogle Scholar |
Davis, N. E., and Coulson, G. (2016). Habitat-specific and season-specific faecal pellet decay rates for five mammalian herbivores in south-eastern Australia. Australian Mammalogy 38, 105–116.
| Habitat-specific and season-specific faecal pellet decay rates for five mammalian herbivores in south-eastern Australia.Crossref | GoogleScholarGoogle Scholar |
Dawson, T. J., McTavish, K. J., and Ellis, B. A. (2004). Diets and foraging behaviour of red and eastern grey kangaroos in arid shrub land: is feeding behaviour involved in the range expansion of the eastern grey kangaroo into the arid zone? Australian Mammalogy 26, 169–178.
Falzon, G., Meek, P. D., Vernes, K., and Bergman, L. D. (2014). Computer-assisted identification of small Australian mammals in camera trap imagery. In ‘Camera Trapping: Wildlife Management and Research’. (Eds P. Meek, P. Fleming, G. Ballard, P. Banks, A. Claridge, J. Sanderson and D. Swann.) (pp. 299–306.) (CSIRO Publishing: Collingwood)
Fancourt, B. (2009). Measurement of defaecation rates in captive swamp wallabies (Wallabia bicolor). Australian Mammalogy 31, 107–110.
| Measurement of defaecation rates in captive swamp wallabies (Wallabia bicolor).Crossref | GoogleScholarGoogle Scholar |
Favreau, F. R., Pays, O., Fritz, H., Goulard, M., Best, E. C., and Goldizen, A. W. (2015). Predators, food and social context shape the types of vigilance exhibited by kangaroos. Animal Behaviour 99, 109–121.
| Predators, food and social context shape the types of vigilance exhibited by kangaroos.Crossref | GoogleScholarGoogle Scholar |
Fletcher, D. (2006). Population dynamics of eastern grey kangaroos in temperate grasslands. Ph.D. thesis, University of Canberra, Canberra.
Fukuda, Y., McCallum, H. I., Grigg, G. C., and Pople, A. R. (2009). Fencing artificial waterpoints failed to influence density and distribution of red kangaroos (Macropus rufus). Wildlife Research 36, 457–465.
| Fencing artificial waterpoints failed to influence density and distribution of red kangaroos (Macropus rufus).Crossref | GoogleScholarGoogle Scholar |
Glass, R., Forsyth, D. M., Coulson, G., and Festa-Bianchet, M. (2015). Precision, accuracy and bias of walked line-transect distance sampling to estimate eastern grey kangaroo population size. Wildlife Research 42, 633–641.
| Precision, accuracy and bias of walked line-transect distance sampling to estimate eastern grey kangaroo population size.Crossref | GoogleScholarGoogle Scholar |
Gowen, C., and Vernes, K. (2014). Population estimates of an endangered rock-wallaby (Petrogale penicillata) using time-lapse photography from camera traps. In ‘Camera Trapping: Wildlife Management and Research’. (Eds P. Meek, P. Fleming, G. Ballard, P. Banks, A. Claridge, J. Sanderson and D. Swann.) (pp. 61–68.) (CSIRO Publishing: Collingwood).)
Grant, T. R. (1973). Dominance and association among members of a captive and a free-ranging group of grey kangaroos (Macropus giganteus). Animal Behaviour 21, 449–456.
| Dominance and association among members of a captive and a free-ranging group of grey kangaroos (Macropus giganteus).Crossref | GoogleScholarGoogle Scholar |
Harvey, P., and Körtner, G. (2014) EXIFTOOL. Available at https://www.sno.phy.queensu.ca/~phil/exiftool/ [Accessed 7 August 2014].
Heise-Pavlov, S. R., and Meade, R. D. (2012). Improving reliability of scat counts for abundance and distribution estimations of Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi) in its rainforest habitats. Pacific Conservation Biology 18, 153–163.
| Improving reliability of scat counts for abundance and distribution estimations of Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi) in its rainforest habitats.Crossref | GoogleScholarGoogle Scholar |
Henderson, T., Rajaratnam, R., and Vernes, K. (2017). Population density of eastern grey kangaroos (Macropus giganteus) in a periurban matrix at Coffs Harbour, New South Wales. Australian Mammalogy 40, 312–314.
Hill, G. J. E. (1978). Preliminary assessment of defecation patterns for the eastern grey kangaroo (Macropus giganteus). Australian Zoologist 19, 291–300.
Hill, G. (1981). A study of grey kangaroo density using pellet counts. Wildlife Research 8, 237–243.
| A study of grey kangaroo density using pellet counts.Crossref | GoogleScholarGoogle Scholar |
Hone, J., and Martin, W. (1998). A study of dung decay and plot size for surveying feral pigs using dung counts. Wildlife Research 25, 255–260.
| A study of dung decay and plot size for surveying feral pigs using dung counts.Crossref | GoogleScholarGoogle Scholar |
Hopkins, H. L., and Kennedy, M. L. (2004). Wildlife Society Bulletin 32, 1289–1296.
Howland, B. (2009). Pellet count techniques for estimating the abundance of eastern grey kangaroos in the A.C.T. B Sc (Hons) Thesis, Australian National University, Canberra.
Hunter, J. T., and Hunter, V. H. (2017). Floristics, dominance and diversity within the threatened Themeda grassy headlands of the North Coast Bioregion of New South Wales. Pacific Conservation Biology 23, 71–80.
| Floristics, dominance and diversity within the threatened Themeda grassy headlands of the North Coast Bioregion of New South Wales.Crossref | GoogleScholarGoogle Scholar |
Jarman, P. J., Jones, M. E., Johnson, C. N., Southwell, C. J., Stuartdick, R. I., Higginbottom, K. B., and Clarke, J. L. (1989). Macropod studies at Wallaby Creek. 8. Individual recognition of kangaroos and wallabies. Australian Wildlife Research 16, 179–185.
| Macropod studies at Wallaby Creek. 8. Individual recognition of kangaroos and wallabies.Crossref | GoogleScholarGoogle Scholar |
Johnson, C. N., and Jarman, P. J. (1987). Macropod studies at Wallaby Creek. 6. A validation of the use of dung-pellet counts for measuring absolute densities of populations of macropodids. Wildlife Research 14, 139–145.
| Macropod studies at Wallaby Creek. 6. A validation of the use of dung-pellet counts for measuring absolute densities of populations of macropodids.Crossref | GoogleScholarGoogle Scholar |
Johnson, C. N., Jarman, P. J., and Southwell, C. J. (1987). Macropod studies at Wallaby Creek. 5. Patterns of defecation by eastern grey kangaroos and red-necked wallabies. Wildlife Research 14, 133–38.
| Macropod studies at Wallaby Creek. 5. Patterns of defecation by eastern grey kangaroos and red-necked wallabies.Crossref | GoogleScholarGoogle Scholar |
Karanth, K. U., and Nichols, J. D. (1998). Estimation of tiger densities in India using photographic captures and recaptures. Ecology 79, 2852–2862.
| Estimation of tiger densities in India using photographic captures and recaptures.Crossref | GoogleScholarGoogle Scholar |
Kaufmann, J. H. (1975). Field observations of the social behaviour of the eastern grey kangaroo, Macropus giganteus. Animal Behaviour 23, 214–221.
| Field observations of the social behaviour of the eastern grey kangaroo, Macropus giganteus.Crossref | GoogleScholarGoogle Scholar |
Kuijper, D. P. J., Verwijmeren, M., Churski, M., Zbyryt, A., Schmidt, K., Jędrzejewska, B., and Smit, C. (2014). What cues do ungulates use to assess predation risk in dense temperate forests? PLoS One 9, e84607.
| What cues do ungulates use to assess predation risk in dense temperate forests?Crossref | GoogleScholarGoogle Scholar |
Landsberg, J., and Stol, J. (1996). Spatial distribution of sheep, feral goats and kangaroos in woody rangeland paddocks. The Rangeland Journal 18, 270–291.
| Spatial distribution of sheep, feral goats and kangaroos in woody rangeland paddocks.Crossref | GoogleScholarGoogle Scholar |
Leuchtenberger, C., Zucco, C. A., Ribas, C., Magnusson, W., and Mourão, G. (2014). Activity patterns of giant otters recorded by telemetry and camera traps. Ethology Ecology and Evolution 26, 19–28.
| Activity patterns of giant otters recorded by telemetry and camera traps.Crossref | GoogleScholarGoogle Scholar |
Maguire, G., Ramp, D., and Coulson, G. (2006). Foraging behaviour and dispersion of eastern grey kangaroos (Macropus giganteus) in an ideal free framework. Journal of Zoology 268, 261–269.
| Foraging behaviour and dispersion of eastern grey kangaroos (Macropus giganteus) in an ideal free framework.Crossref | GoogleScholarGoogle Scholar |
McCallum, H. I. (1999). How to count kangaroos. Australian Zoologist 31, 309–316.
| How to count kangaroos.Crossref | GoogleScholarGoogle Scholar |
Meek, P., and Pittet, A. (2013). User-based design specifications for the ultimate camera trap for wildlife research. Wildlife Research 39, 649–660.
| User-based design specifications for the ultimate camera trap for wildlife research.Crossref | GoogleScholarGoogle Scholar |
Meek, P. D., Zewe, F., and Falzon, G. (2012). Temporal activity patterns of the swamp rat (Rattus lutreolus) and other rodents in north-eastern New South Wales, Australia. Australian Mammalogy 34, 223–233.
| Temporal activity patterns of the swamp rat (Rattus lutreolus) and other rodents in north-eastern New South Wales, Australia.Crossref | GoogleScholarGoogle Scholar |
Meek, P., Fleming, P., Ballard, G., Banks, P. B., Claridge, A., Sanderson, J., and Swann, D. E. (2014a). ‘Camera Trapping: Wildlife Management and Research.’ (CSIRO Publishing: Collingwood)
Meek, P. D., Ballard, G., Claridge, A., Kays, R., Moseby, K., O’Brien, T., O’Connell, A., Sanderson, J., Swann, D. E., Tobler, M., and Townsend, S. (2014b). Recommended guiding principles for reporting on camera trapping research. Biodiversity and Conservation 23, 2321–2343.
| Recommended guiding principles for reporting on camera trapping research.Crossref | GoogleScholarGoogle Scholar |
Morgan, H. R., Reid, N., and Hunter, J. T. (2018). Estimation of above-ground herbaceous biomass using visually ranked digital photographs. The Rangeland Journal 40, 9–18.
| Estimation of above-ground herbaceous biomass using visually ranked digital photographs.Crossref | GoogleScholarGoogle Scholar |
Neff, D. J. (1968). The pellet-group count technique for big game trend, census, and distribution: a review. The Journal of Wildlife Management 32, 597–614.
| The pellet-group count technique for big game trend, census, and distribution: a review.Crossref | GoogleScholarGoogle Scholar |
Norton, M. A., Sharp, A., and Marks, A. (2011). An evaluation of faecal pellet counts to index rock-wallaby population size. Australian Mammalogy 33, 221–227.
| An evaluation of faecal pellet counts to index rock-wallaby population size.Crossref | GoogleScholarGoogle Scholar |
O’Connell, A. F., Nichols, J. D., and Karanth, K. U. (2010). ‘Camera Traps in Animal Ecology: Methods and Analyses.’ (Springer Science & Business Media: Berlin.)
Palei, H. S., Pradhan, T., Sahu, H. K., and Nayak, A. K. (2016). Estimating mammalian abundance using camera traps in the tropical forest of Similipal Tiger Reserve, Odisha, India. Proceedings of the Zoological Society 69, 181–188.
| Estimating mammalian abundance using camera traps in the tropical forest of Similipal Tiger Reserve, Odisha, India.Crossref | GoogleScholarGoogle Scholar |
Perry, R. J., and Braysher, M. L. (1986). A technique for estimating the numbers of eastern gray kangaroos, Macropus giganteus, grazing a given area of pasture. Australian Wildlife Research 13, 335–338.
| A technique for estimating the numbers of eastern gray kangaroos, Macropus giganteus, grazing a given area of pasture.Crossref | GoogleScholarGoogle Scholar |
Pfeffer, S. E., Spitzer, R., Allen, A. M., Hofmeester, T. R., Ericsson, G., Widemo, F., Singh, N. J., and Cromsigt, J. P. G. M. (2017). Pictures or pellets? Comparing camera trapping and dung counts as methods for estimating population densities of ungulates. Remote Sensing in Ecology and Conservation 4, 173–183.
| Pictures or pellets? Comparing camera trapping and dung counts as methods for estimating population densities of ungulates.Crossref | GoogleScholarGoogle Scholar |
Pople, A. R., Cairns, S. C., Menke, N., and Payne, N. (2006). Estimating the abundance of eastern grey kangaroos (Macropus giganteus) in south-eastern New South Wales, Australia. Wildlife Research 33, 93–102.
| Estimating the abundance of eastern grey kangaroos (Macropus giganteus) in south-eastern New South Wales, Australia.Crossref | GoogleScholarGoogle Scholar |
Ramp, D., and Coulson, G. (2002). Density dependence in foraging habitat preference of eastern grey kangaroos. Oikos 98, 393–402.
| Density dependence in foraging habitat preference of eastern grey kangaroos.Crossref | GoogleScholarGoogle Scholar |
Rovero, F., and Marshall, A. R. (2009). Camera trapping photographic rate as an index of density in forest ungulates. Journal of Applied Ecology 46, 1011–1017.
| Camera trapping photographic rate as an index of density in forest ungulates.Crossref | GoogleScholarGoogle Scholar |
Rovero, F., Collett, L., Ricci, S., Martin, E., and Spitale, D. (2013). Distribution, occupancy, and habitat associations of the gray-faced sengi (Rhynchocyon udzungwensis) as revealed by camera traps. Journal of Mammalogy 94, 792–800.
| Distribution, occupancy, and habitat associations of the gray-faced sengi (Rhynchocyon udzungwensis) as revealed by camera traps.Crossref | GoogleScholarGoogle Scholar |
Rowcliffe, J. M., and Carbone, C. (2008). Surveys using camera traps: are we looking to a brighter future? Animal Conservation 11, 185–186.
| Surveys using camera traps: are we looking to a brighter future?Crossref | GoogleScholarGoogle Scholar |
Rowcliffe, J. M., Field, J., Turvey, S. T., and Carbone, C. (2008). Estimating animal density using camera traps without the need for individual recognition. Journal of Applied Ecology 45, 1228–1236.
| Estimating animal density using camera traps without the need for individual recognition.Crossref | GoogleScholarGoogle Scholar |
Schultz, N. L., Reid, N., Lodge, G. M., and Hunter, J. T. (2014). Seasonal and interannual variation in vegetation composition: Implications for survey design and data interpretation. Austral Ecology 39, 755–766.
| Seasonal and interannual variation in vegetation composition: Implications for survey design and data interpretation.Crossref | GoogleScholarGoogle Scholar |
Short, J., and Hone, J. (1988). Calibrating aerial surveys of kangaroos by comparison with drive counts. Wildlife Research 15, 277–284.
| Calibrating aerial surveys of kangaroos by comparison with drive counts.Crossref | GoogleScholarGoogle Scholar |
Silveira, L., Jácomo, A. T. A., and Diniz-Filho, J. A. F. (2003). Camera trap, line transect census and track surveys: a comparative evaluation. Biological Conservation 114, 351–355.
| Camera trap, line transect census and track surveys: a comparative evaluation.Crossref | GoogleScholarGoogle Scholar |
Southwell, C. J. (1984). Variability in grouping in the eastern grey kangaroo, Macropus giganteus I. Group density and group size. Wildlife Research 11, 423–435.
| Variability in grouping in the eastern grey kangaroo, Macropus giganteus I. Group density and group size.Crossref | GoogleScholarGoogle Scholar |
Southwell, C. (1989). Techniques for monitoring the abundance of kangaroo and wallaby populations. In ‘Kangaroos, Wallabies and Rat-Kangaroos’. Vol. 2. (Eds G. C. Grigg, P. J. Jarman and I. Hume.), (pp. 659–693.) (Surrey Beatty and Sons: Sydney.)
Southwell, C. J., Weaver, K. E., Cairns, S. C., Pople, A. R., Gordon, A. N., Sheppard, N. W., and Broers, R. (1995). Abundance of macropods in north-eastern NSW and the logistics of broad-scale ground surveys. Wildlife Research 22, 757–766.
| Abundance of macropods in north-eastern NSW and the logistics of broad-scale ground surveys.Crossref | GoogleScholarGoogle Scholar |
Sparkes, J., Ballard, G., Fleming, P. J. S., van de Ven, R., and Körtner, G. (2016). Contact rates of wild-living and domestic dog populations in Australia: a new approach. Oecologia 182, 1007–1018.
| Contact rates of wild-living and domestic dog populations in Australia: a new approach.Crossref | GoogleScholarGoogle Scholar |
Sullivan, B. J., Baxter, G. S., and Lisle, A. T. (2002). Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. I. Faecal pellet sampling protocol. Wildlife Research 29, 455–462.
| Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. I. Faecal pellet sampling protocol.Crossref | GoogleScholarGoogle Scholar |
Swann, D. E., and Perkins, N. (2014). Camera trapping for animal monitoring and management: a review of applications. In ‘Camera Trapping: Wildlife Management and Research’. (Eds P. Meek, P. Fleming, G. Ballard, P. B. Banks, A. Claridge, J. Sanderson and D. E. Swann.) (pp. 3–11) (CSIRO Publishing: Collingwood.)
Tobler, M. W., Carrillo-Percastegui, S. E., and Powell, G. (2009). Habitat use, activity patterns and use of mineral licks by five species of ungulate in south-eastern Peru. Journal of Tropical Ecology 25, 261–270.
| Habitat use, activity patterns and use of mineral licks by five species of ungulate in south-eastern Peru.Crossref | GoogleScholarGoogle Scholar |
Vernes, K. (1999). Pellet counts to estimate density of a rainforest kangaroo. Wildlife Society Bulletin 27, 991–996.
Vernes, K., and Jarman, P. J. (2014). Long-nosed potoroo (Potorous tridactylus) behaviour and handling times when foraging for buried truffles. Australian Mammalogy 36, 128–130.
| Long-nosed potoroo (Potorous tridactylus) behaviour and handling times when foraging for buried truffles.Crossref | GoogleScholarGoogle Scholar |
Wang, S. W., and Macdonald, D. W. (2009). The use of camera traps for estimating tiger and leopard populations in the high altitude mountains of Bhutan. Biological Conservation 142, 606–613.
| The use of camera traps for estimating tiger and leopard populations in the high altitude mountains of Bhutan.Crossref | GoogleScholarGoogle Scholar |
Zabek, M. A., Berman, D. M., Blomberg, S., and Wright, J. P. (2016). Estimating distribution and abundance of feral horses (Equus caballus) in a coniferous plantation in Australia, using line-transect surveys of dung. Wildlife Research 43, 604–614.
