The reintroduction of wolves into many regions in the Northern Hemisphere is massively controversial, and even a constant parliamentary debate in some countries. There are no doubts that wolves bring considerable benefits to local biodiversity wherever they are reintroduced, but there are also no doubts that their reintroduction is met with trepidation by the local human populace.
That makes figuring out where conflicts are likely to arise and wolves and likely to be shot, poisoned, or hit by a car really important. If we can figure out where wolves are most likely to be killed, it can help conservationists figure out where their populations need the most attention, and where outreach to local farmers could prevent further conflicts. That’s what today’s authors wanted to figure out.
Image Credit: Rick Heeres, CC BY 2.0, Image Cropped
Multiple species-specific molecular markers using nanofluidic array as a tool to detect prey DNA from carnivore scats (2021) Di Bernardi et al., Ecology & Evolution. https://doi.org/10.1002/ece3.7918
Studying carnivore diet can be a crucial tool to inform both management and conservation of predators and their prey. If we’re going to ensure a carnivore’s survival, we need to know which species it relies on for food, and in what quantities.
Digging into an animal’s stomach isn’t the nicest way to get the crucial data we’re looking for, so non-invasive sampling of scats (that’s science for poop) has for been a more ideal approach to collecting valuable information on the occurrence, genetics, and diet of animals, especially when dealing with elusive and threatened species. Nowadays, DNA-based analyses of scats are allowing researchers to get more and more high-resolution data on predators’ food habits.
What We Did
We developed a DNA-based method to detect prey from wolf scats, taking advantage of the huge leaps the DNA analysis has been through in recent years. We also made use of nanotechnology (specifically Nanofluidic array technology fromFluidigm Inc.), which has been useful for detecting pathogen species in ticks, or traces of herbivores on browsed twigs, but has never applied to detect prey from predator scats!
Starting from the big bank of DNA sequences available online (GenBank, NCBI), we looked at specific areas of the genome, (the mitochondrial genome), in order to tell apart the different target prey species present in the wolf scat. We developed species-specific molecular markers (see Did You Know?) and tested them with reference tissue samples, kindly provided by the Swedish Museum of Natural History. After the protocol development and optimization, we ended up with a set of 80 markers for our 18 target species. We then applied the newly developed molecular method on a pilot sample of wolf scats collected in the field.
Did You Know: Molecular Markers
Since any species’ genome is an incredibly long sequence, scientists have developed more efficient ways of defining what DNA belongs to which species. The motivation is simple – if you’re trying to tell whether a genome belongs to a human or to a chimpanzee, you don’t want to be looking through the 99% of DNA we have in common, you want to go straight to that 1%. That’s why scientists develop ‘markers’. It helps them narrow down their search and identify species much more quickly.
What We Found
The molecular markers we developed did their job well, correctly detecting the 18 prey species, showing an overall good distinction between the tissue samples of the target and non-target species. In other words, this means that a tissue sample taken from a moose was detected by the moose markers but not by the reindeer markers, which is the sign of a successful marker!
When applied to the pilot of wolf scats collected in the wild, the method detected a total of 16 species, comprising wild ungulates (moose, roe deer, red deer, fallow deer, wild boar), domestic and semi-domestic animals (reindeer, cattle, sheep), small prey species (European badger, European hare, mountain hare, Western capercaillie, black grouse), and other carnivores (Eurasian lynx, wolverine, red fox).
While the method detects the target species as we’d like, it cannot distinguish whether predation, scavenging, or territorial marking has occurred. Detection of fox DNA in wolf scats can mean a wolf predating on a fox, a wolf scavenging on a fox, but also a fox marking with its urine on a wolf scat! To partly disentangle this aspect, we are investigating the contribution of scavenging to wolves diet in Scandinavia, with data from GPS-collared wolves.
This molecular method, with its high-resolution prey detection, can help better understanding under what circumstances wolves eat certain prey and how that can affect ungulate populations, serving as a valuable complement to the current GPS technology used to investigate wolf predation. Wolf natural expansion is an ongoing and controversial phenomena in the Northern hemisphere, and any technique that tells us more about their impact is a welcome addition to our knowledge base.
Cecilia Di Bernardi is an ecologist who is currently investigating wolf predation ecology within her PhD at the University of Rome La Sapienza in collaboration with SLU Swedish University of Agricultural Sciences. You can follow her on Twitter @c_dibernardi.
Okay so maybe the wolves aren’t literally helping deers to cross roads in Wisconsin, but they are helping to keep them away from the motorways and (by extension) preventing them from becoming another roadkill statistic.
With the return of wolves to Wisconsin, their prey species have had to change their behaviour to minimise the risk of becoming the next item on the menu. One of these changes has been to avoid roadways and other human structures, since these cleared areas make ideal wolf hunting grounds. They do of course also catch the odd deer, but it is the added ability to scare the deer away from roadways which makes wolves a more efficient prevention technique for deer collisions than the traditional approach of keeping deer population down through hunting.
Wolves are a polarising topic – with divided opinions as to if they should be re-introduced to the wild or not. This landscape of fear that the wolves create is clearly a tick in the win column for having wolves around. As twitter user @edyong209 points out; the wolves could actually be helping us solve a human engineered problem by keeping the deers at bay.
We tend to think of the concept of large herbivores roaming freely around Europe as a notion confined to the ancient past. Yet in geological terms, huge herbivores and their associated carnivores were widespread on the European continent only a short time ago. With many ecosystems badly degraded, the idea of restoring ecological processes and enhancing biodiversity by reintroducing everything from bisons to elephants has been tossed around more and more.
But how do the reintroduction of these species help European ecosystems? To learn more about the phenomena, I spoke to Professor Jens-Christian Svenning, who has spoken extensively about the advantages of bringing large herbivores and carnivores back to the European mainland. We discussed what rewilding means, some recent success stories, and why living with megafauna in Europe is no harder than in any other part of the world.
Many parliamentary debates in Norway cover ground that is familiar to other countries; climate change, the economy, pandemic responses. Yet I’m happy to say there’s one issue that is more unique to this part of the world: what to do with all these wolves. Once native to Norway, wolves, bears and wolverines were largely pushed out of the country, but started to come back into parts of Norway in the 1970s after they became protected. Despite what one of Liam Neeson’s better old-man-action films would have you believe, wolves are shy but curious creatures and of no real danger to people. However their reintroduction has generally been met with a mix of both consternation and celebration, with urban populations cheering the reintroduction of a former native and rural populations wary of the thought of sharing space with wolves.
When we think of wolves, and more specifically what they like to eat, the first thing that comes to mind is often the image of a pack tirelessly hunting down large ungulates. It’s a high octane, endurance race to the death – one which also involves some tag teaming.
Well it turns out these endurance specialists are able to trade in their usual cursorial (fancy word for running your prey down) approach to hunting for a more ambush (less fancy word for sitting very still and jumping out on something) style depending on their choice of prey. Researchers found that when wolves turned their eyes to other prey types such as beavers, they adopted a sit-and-wait tactic more commonly seen in cats. They were often even observed waiting downwind so as to avoid the beavers keen sense of smell.
It’s cool to know that we are still learning new things about these charismatic and well studied animals – in this case their ability to ‘activate’ ambush mode should the need arrive.
Tanya Strydom is a PhD student at the Université de Montréal, mostly focusing on how we can use machine learning and artificial intelligence in ecology. Current research interests include (but are not limited to) predicting ecological networks, the role species traits and scale in ecological networks, general computer (and maths) geekiness, and a (seemingly) ever growing list of side projects. Tweets (sometimes related to actual science) can be found @TanyaS_08.
Language is important. It’s a lesson many biological scientists would have learned a long time ago if we hadn’t kept social sciences at such a wary arm’s length. Ecologists have a tendency to label and relabel ecological concepts (anyone up for a debate about the word ‘niche’?), species and even global phenomena (think global warming vs. climate change) based on anything from shifts in public perception to new findings that challenge our earlier labels.
The ultimate goal of species conservation is to preserve a species’ existence in the natural world. To effectively do this, we must know the extent of “species” that we want to conserve. That may sound simple, but the concept of hybridisation can blur the lines of where one species begins and another ends beyond recognition.
Rewilding is a tricky business. Bringing back species that once roamed a country as their native land may seem like a worthy cause, but it is often fraught with conflict. People don’t want predators threatening their safety, or herbivores destroying their crops. Rural vs. urban tensions come into play. Local and federal politics get thrown into the mix.
With that in mind, I sat down with Associate Professor Fredrik Widemo, currently a Senior lecturer with the Swedish University of Agricultural Sciences. Fredrik has previously worked at both the Swedish Association for Hunting and Wildlife Management (where he was the Director of Science) and the Swedish Biodiversity Centre. We explored some of the complexities behind the rewilding of wolves and its effects on the hunting and forestry industries in Sweden.
Image Credit: Doug Smith, NPS, Public Domain, Image Cropped
Can you imagine a wild Scandinavia filled with untamed forests, wild boar, and large predators (and maybe a stray Viking)? This is the dream of some scientists advocating for the reintroduction of species once found in Europe that have either been hunted to extinction or driven out by intensive agriculture. The reintroduction of species, particularly animals dubbed “ecosystem engineers” such as beavers and large carnivores are of special interest due to the positive landscape-level effects of these species.