In August 2016, a herd of over 300 reindeer were killed when lightning struck Norway’s Hardangervidda mountain plateau. As the animals huddled together for warmth, a surge of current – possibly from multiple lightning strikes – coursed through the sodden earth, bolted up the reindeers’ legs into their bodies and delivered a fatal jolt of electricity to their hearts.
Two years later, the remains of the rotting carcasses still pepper the plateau (save for their heads, which were removed by local officials shortly after the die-off to test for chronic wasting disease). Now, Norwegian scientists are discovering how this carcass-strewn landscape and the scavengers it attracts have the potential to foster new plant growth and alter biodiversity across the alpine tundra.
While most would turn their nose up at a landscape littered with 323 reindeer carcasses, Dr Sam Steyaert, a researcher at the University of South-Eastern Norway and the Norwegian University of Life Sciences, decided to use the tragedy as an opportunity for scientific study.
Along with a group of collaborators, he created a self-funded project called "REINCAR” – short for "reindeer carcass" and also the first six letters of the word "reincarnation” – and got to work setting up a field laboratory. "The initial goal of REINCAR was to assess ecological change in general in response to this mass die-off," Steyaert explained to us via email. This required a holistic approach monitoring everything from biogeochemistry to microorganisms.
Initial visits to the site revealed that the carcasses had atrracted a varied crowd of eager scavengers. Camera traps set up in the area by Steyaert and his team recorded everything from foxes and wolverines, to golden eagles and common ravens. The researchers also noticed a fair share of faeces littering the ground, some of which contained crowberry seeds.
Crowberry plants (Empetrum nigrum) are a keystone species that help shape the alpine tundra. They serve as an important food source for many animals and without them the ecosystem would be significantly different. The seedlings require bare, nutrient-rich soil to germinate – conditions that rotting carcasses can help to create. “During decomposition of larger terrestrial animals such as many ungulates, plant life in the immediate vicinity of a carcass turns chlorotic and dies from abrupt shifts in soil nutrient concentrations and acidity, turning the affected patch into a ‘cadaver decomposition island’,” the researchers point out in a paper published recently in Biology Letters.
To better understand how these “cadaver decomposition islands” affect the ecosystem and the role that scavengers play in dispersing seeds, Steyaert and his team began diligently documenting and collecting poop (science is rarely a glamorous endeavour). Using survey plots, they were able to confirm their suspicions that scavengers like foxes and birds were spending much of their time in carrion-dense areas, and they were certainly breaking that cardinal rule about not pooping where one eats.
Lab tests later confirmed that 21 out of the 24 crow faecal samples that were collected at the site contained viable crowberry seeds that had the potential to sprout into seedlings. A more recent visit to the area confirmed the lab evidence: the team noticed that several crowberry seedlings had shot up across the field.
"Our study provides novel insight into how scavengers may have landscape-level effects on plant distribution," the authors wrote in the study. While the death of 323 reindeer is a devastating loss, from this tragedy sprouts new life. The reindeer carcasses created the perfect conditions under which plants like the crowberry could flourish. Throw in some hungry scavengers with seeds in their poop and you have a recipe for biological renaissance.
Of course, a landscape strewn with carcasses is an extreme event, one that's likely to shape this particular patch of alpine tundra in unique ways for years to come. To truly understand "directed seed dispersal by scavengers towards animal carcasses on the landscape scale, one would need to monitor this process at locations of individual carcasses, of animals that died in a more ‘normal’ setting (killed by hunters, starvation, vehicle collisions, etc.)," Steyaert points out. "Furthermore, it would be great to monitor how that actually contributes to genetic variation and population dynamics of the dispersed species."
Steyaert and his team hope to revisit the site in the coming years and are eager to see how the area develops. After all, it's not everyday that you come across 300-plus reindeer carcasses rotting on a remote alpine tundra.
Top header image: Lía, Flickr
WTF!?
Backyard wildlife
Animal Behaviour
