Identification of Carnivore Feces by Local Peoples and Molecular Analyses

1. What they did

Carnivores are hard to study: they are elusive, spread thinly and dangerous to handle, and capturing them is costly and can change their behaviour. The authors looked at two alternatives: the traditional ecological knowledge (TEK) of indigenous and local people, and DNA taken from scats. They had two aims: to develop a DNA test that tells apart the scats of the dogs and cats of the Mbaracayú Reserve in eastern Paraguay, and to use that test to check how well indigenous Aché people and local reserve rangers identify scats in the field.

• Rangers’ collection. Six rangers searched the forest and cerrado around 7 ranger stations, looking for game trails and other signs, and followed fresh animal trails until they found scats. Every scat found was collected with sterile tools, its location recorded by Global Positioning System (GPS), and named in the field by one ranger. The most experienced ranger then examined each sample and made the final identification.
• Aché collection. At least 10 Aché people collected scats on their hunting and foraging trips into the reserve, using fresh twigs as tongs, and labelled each with the species name in the Aché language. They were paid 20,000 Guaranis (about US$5 at the time) for each sample.
• The DNA test. The authors built the test from published DNA sequences of the 12 dog and cat species that may live in the reserve. They checked it on scats from zoo animals before using it on the field samples.
• The comparison. They compared each DNA identification with the name given in the field.

2. What they found

DNA success

• They tried the DNA test on 172 scats from the rangers and 66 from the Aché: 238 in total.
• The test gave a species for 124 ranger scats (72.1%) and 62 Aché scats (93.9%), 186 overall (78.2%).
• Most of the scats that failed were dry and looked old. Most of these were collected by rangers and named in the field as crab-eating fox, and they were made up largely of palm fruit.

Species found

• Dogs: 11 bush dog, 17 maned wolf and 34 crab-eating fox. No pampas fox.
• Large cats: 36 jaguar, 26 puma and 5 jaguarundi.
• Small spotted cats: 11 ocelot, 29 oncilla, 10 margay and 7 Geoffroy’s cat. No pampas cat.
• Most rangers’ scats were from dogs. The Aché brought only one dog scat; their scats were almost all cats, large and small in about equal numbers. The authors explain this partly by the Aché seldom foraging in the eastern, cerrado part of the reserve, where maned wolves and foxes are common.

Field identifications versus DNA

• All 124 ranger scats identified by DNA matched the ranger’s field identification exactly.
• Of the 62 Aché scats identified by DNA, 42 matched the species named in the field exactly. The other 20 were margay, oncilla or Geoffroy’s cat. The Aché had called them all “kajamini”, one Aché word that covers these three small spotted cats. So the Aché told this group apart from ocelots and jaguarundis, but did not name the species within it.
• The authors report this as 100% agreement between the DNA and the field identifications.
• Both rangers and Aché were confident of all their field identifications.

3. What they concluded

• The DNA test worked and identified most scats. The cytochrome-b gene is useful for telling apart scats of closely related species.
• The Aché and rangers who worked on the study reliably identified dog and cat scats. Because their identifications were right for every sample the DNA could check, the authors concluded the field names for the samples that failed the DNA test were also accurate.
• The Aché skill was not surprising to the authors: before 1978 the Aché lived as nomads in the forests of eastern Paraguay, and finding food and avoiding dangerous animals such as jaguars depended on reading animal signs. Some rangers also have life-long dependence on the forest.
• Only a few individuals were tested. The authors suspect most younger Aché and inexperienced rangers would not be as accurate, and suggest testing people who have not depended on wildlife.
• Some rangers and Aché hold valuable TEK and can be reliable sources of data on carnivores. Checking local knowledge with DNA can establish its credibility for future studies.

4. How tracking was or was not used

The whole study tests scat identification in the field. Rangers searched for game trails and other signs and followed fresh animal trails until they found scats, then identified each scat to species. The Aché found and identified scats during their usual hunting and foraging trips. Field identifications were then checked against DNA from the same scats.

5. Tracker or observer certification

No certification is reported. The rangers’ skill, and that of at least 10 Aché collectors, was tested in this study against DNA identification. The final ranger identifications were made by “the most experienced ranger”; how many Aché made the identifications, and how experienced they were, is not described. The authors note that the results reflect the ability of only a few individuals.

6. Other technologies, skills or innovations

• A DNA test built for this reserve: three primer sets (dogs, small spotted cats and large cats) and a set of restriction enzymes for each group, read with a decision flow chart, to name 12 possible species.
• The test was checked on scats from zoo bush dogs, maned wolves, jaguars and ocelots.
• Garmin 12 XL GPS receiver to record each scat location.
• Scats were kept on ice in the field and frozen within 72 hours.

7. Implications for conservation (from the paper)

• Several of the reserve’s carnivores are endangered. Working with indigenous and local people can be especially important for elusive or endangered species and for disappearing habitats, and helps bridge the gap between western scientists and local people.
• Once the credibility of local people’s knowledge is checked, money and time can be saved or put to other field research and management.
• The Aché already collect most field data for human dimensions research in the reserve, and their knowledge is central to its management.