Sniffing for science
It is often difficult to find out exactly where individual species still occur and how their populations are developing. Specially trained detection dogs can be a help in such cases.
03/03/2021 · Lebenswissenschaften · Leibniz-Institut für Zoo- und Wildtierforschung · News · Forschungsergebnis
The lists of the world’s endangered animals and plants are getting increasingly longer. But to stop this trend, important information is lacking. It is often difficult to find out exactly where individual species still occur and how their populations are developing. Specially trained detection dogs can be a valuable help in such cases, as a new scientific publication review shows. With the help of detection dogs the searched species can usually be found faster and more effectively than with other methods, report Dr Annegret Grimm-Seyfarth and Wiebke Harms from the Helmholtz Centre for Environmental Research (UFZ) and Dr Anne Berger from the Leibniz-Institute for Zoo and Wildlife Research (Leibniz-IZW) in the scientific journal "Methods in Ecology and Evolution".
How many otters are still there in Germany? What habitats do the endangered great crested newts use on land? And do urban hedgehogs have to deal with different problems than their rural conspecifics? “Anyone who wants to effectively protect a species should be able to answer such questions. But this is by no means easy. After all, many animals lead a secretive life in hiding, and their traces, especially their excretions, are often difficult to find,” explains Dr Anne Berger, evolutionary ecologist at the Leibniz-IZW. It is therefore often unclear whether and at what rate populations are declining or where the remaining survivors are. "We urgently need to know more about these species," says Dr Annegret Grimm-Seyfarth of the UFZ. "But we first have to find them."
When it comes to mapping open landscapes or detecting larger animals, remote sensing with aerial and satellite imagery can help. For densely vegetated areas and smaller, hidden species, on the other hand, experts traditionally do the search themselves or work with cameras, hair traps and similar tricks. Recently, other techniques such as the analysis of tiny traces of genetic material have attracted increasing interest worldwide. And it is precisely for this purpose that the use of specially trained detection dogs can be very useful. After all, a dog’s sense of smell is virtually predestined to find the smallest traces of the target species. While humans have about six million olfactory receptors, a herding dog has more than 200 million, and a beagle even 300 million. This means that dogs can perceive an extremely wide range of odours, often in the tiniest concentrations. For example, they can easily find animal droppings in a forest or plants, mushrooms, and animals under the ground.
At the UFZ and the Leibniz-IZW, the detection dogs have already demonstrated successfully their abilities in several research projects. "In order to be able to better assess their potential, we wanted to know how detection dogs have previously been used around the world," says Grimm-Seyfarth. Together with UFZ employee Wiebke Harms and Dr Anne Berger from the Leibniz-IZW in Berlin, Grimm-Seyfarth has evaluated 1,220 publications documenting the use of such detection dogs in more than 60 countries. "We were particularly interested in which dog breeds were used, which species they were supposed to track down, and how well they performed," explains the scientist.
The longest experience with detection dogs is in New Zealand, where dogs have been tracking threatened birds already around 1890. Since then, the idea has been implemented in many other regions, especially in North America and Europe. The publications analysed, focused mainly on finding animals, their dwellings, tracks and remains. More than 400 animal species were in the focus, most frequently mammals from the cat, dog, bear and marten families. But birds and insects were also on the wanted lists. In addition, there were 42 plant, 26 fungal and 6 bacterial species. These were not always endangered species. Sometimes the dogs sniffed out pests such as bark beetles or invasive plants such as knotweed or ragweed.
"In principle, all dog breeds can be trained for such tasks," says Grimm-Seyfarth. "Only with some it is more elaborate than with others." Pinschers or Schnauzers, for example, are now bred more as companion dogs and therefore often do not show as much motivation for tracking species. And terriers tend to immediately snatch their targets - which is, of course, not desirable. Pointers and setters, on the other hand, were bred specifically to find and point out game - but not to hunt it. That is why these breeds are popular in North America, the UK and Scandinavia for use in science and conservation projects to track ground-nesting birds such as ptarmigans and wood grouse. Retrievers and herding dogs also have qualities that make them very good helpers in species tracking. They are eager to learn, easy to motivate, enjoy working with people, and generally do not have a strong hunting instinct. That is why Labrador Retrievers, Border Collies, and German Shepherds are among the most popular detection dogs worldwide.
Grimm-Seyfarth’s Border Collie Zammy learned as a puppy how to detect the droppings of otters. This is a valuable contribution to science. Because these droppings can be genetically analysed to find out which individual they come from, how closely they are related to other conspecifics and what they have eaten. But these telltale traces are not so easy to find even for experienced experts, especially small and dark-coloured droppings are easily overlooked. Dogs, on the other hand, can sniff out even the most inconspicuous droppings indiscriminately. In an earlier UFZ study, they found four times as many droppings as human trackers. And the fact that Zammy is now searching in parallel for great crested newts makes his work even more worthwhile.
According to the publication overview, many other teams around the world have had similarly good experiences. In almost 90 percent of the cases, the dogs worked much more effectively than other detection methods. Compared with camera traps, for example, they detected between 3.7 and 4.7 times more black bears, pied martens, and bobcats. In addition, they often reach their target particularly quickly. "They can find a single plant on a football field in no time," says Grimm-Seyfarth. They are even able to discover underground plant parts.
However, there are also cases where the use of detection dogs is not the method of choice. Rhinos, for example, leave their large piles of excrement clearly visible on paths so that humans can easily find them on their own. And animal species that know feral dogs as enemies are more likely to flee in detection dog company than to be found.
"However, in most cases where the detection dogs did not perform so well, it was owed by inadequate training," says Grimm-Seyfarth. She believes that good training is the most important recipe for success when using detection dogs. "If you select the right dog, know enough about the target species, and design the study accordingly, this can be an excellent detection method". She and her colleagues are already planning further missions for their useful detection dogs. A new project that involves tracking down invasive plant species will soon be launched.
Annegret Grimm-Seyfarth, Wiebke Harms, Anne Berger: Detection dogs in nature conservation: A database on their worldwide deployment with a review on breeds used and their performance compared to other methods. Methods in Ecology and Evolution (2021), DOI: 10.1111/2041-210X.13560. https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/2041-210X.13560