True detective: Not every bear is a hive-breaker
Some tales say that when bears smell honey, they cannot resist. Like at a crime scene, a team of researchers has tracked the DNA left by brown bears breaking into apiaries in the north-eastern Carpathians to reveal who were the perpetrators of the alleged offences. They found that only a third of the bears living in the region could be declared as the culprits of beehive destruction, and that not all individuals were equally liable. Just a few bears (nine out of the 72 living in the area) were classified as repeat offenders, while the rest of the damage-makers break into apiaries only occasionally.
In early April 2014, in a small village surrounded by the Carpathian forest, about 100 kilometres north-west of the Kremenaros tripoint where the borders of Poland, Slovakia and Ukraine meet, a beekeeper went to check his hives after the winter season. He had been running the apiary for more than three decades and, despite living in a region inhabited by brown bears, he had never suffered any bear damage. Nor had he ever properly protected his beehives against bears. Considering that bears cause about 52 damages per year in a region of 4700 km2, most of them (92%) in apiaries, the beekeeper has been somewhat fortunate. Until that day. He found fifteen destroyed hives in his small apiary. A few days earlier, a very similar scenario had occurred in another village just five kilometres away.
Equipped with gloves, vials and a cool box, the team of researchers from the Institute of Nature Conservation of the Polish Academy of Sciences soon arrived at the "crime" sites to search for biological material, mostly hairs, but also faeces left by the bears presumably involved in the offence. The researchers carefully inspected the damaged beehives, hive frames, fences and surrounding area in their search for evidence. As if they were at a crime scene, the scientists secured all biological samples, transported them to the laboratory in Kraków and extracted DNA to identify the individuals responsible for destroying the beehives. They found that a female with two cubs was involved in both apiary break-ins. Three years later, she was identified as being implicated in two similar incidents.
Over four years, the team of researchers and wildlife managers from the Regional Directorate for Environmental Protection in Rzeszów inspected 209 sites reported as presumably damaged by bears, and collected and analysed 146 biological samples. In parallel, the team conducted a year-long systematic genetic sampling across this large region, and then used complex statistical models to provide the first accurate estimate of the number of bears living in the Polish Eastern Carpathians. This has never been an easy task as these animals are elusive, rare and move over large areas. But the team knew how to provoke the bears to rub against certain trees and leave their hairs there. They set up special hair traps baited with an attractive scent and collected as many as 169 hair samples.
Using the genetic information contained in the collected hairs and scats, the team estimated that between 45 and 115 bears inhabit the study area. "We found that out of an average of 72 bears living in the region, just one third break into apiaries", states Teresa Berezowska-Cnota, lead author of the study. But what makes this finding even more exciting is that not all individuals were identified at damage sites equally frequently. "The common view is that if someone has behaved badly once, they will behave similarly badly in the future. We showed that this is rather the exception in the case of brown bears", she adds. Of the bears breaking into apiaries, about 33% were repeat offenders. This means that only a small fraction of the population could be classified as "problem" individuals.
This study has important implications for wildlife conservation and for the management of conflicts between humans and wild animals. Nuria Selva, the senior author of the study, believes that to effectively solve human-wildlife conflicts, we need to deal with both sides of the coin. "On the one side, there are humans. We still have a lot to do in terms of damage prevention. Most apiaries and livestock are not properly protected in areas inhabited or being recolonized by large carnivores, which is like leaving the door open for conflicts", she explains. "On the other side is the wildlife. Without identifying the particular animals involved in conflicts and understanding their behaviour, conflicts cannot really be resolved". The study points out that understanding the individual aspects of conflict behaviour through large spatiotemporal scales and population-wide studies should be a priority in applied ecology and conservation.
The study has just been published in Journal of Applied Ecology. It was funded by the National Science Centre in Poland and is the result of the collaboration between the Institute of Nature Conservation of the Polish Academy of Sciences, Estación Biológica de Doñana CSIC, the German Centre for Integrative Biodiversity Research, the Regional Directorate for Environmental Protection in Rzeszów, and the Bieszczady and Magura National Parks.
Teresa Berezowska-Cnota, Maciej K. Konopi?ski, Kamil Barto?, Carlos Bautista, Eloy Revilla, Javier Naves, Aleksandra Biedrzycka, Hubert Fedy?, Néstor Fernández, Tomasz Jastrz?bski, Bartosz Pirga, María Viota, Zenon Wojtas, Nuria Selva. Individuality matters in human-wildlife conflicts: patterns and fraction of damage-making Brown bears in the north-eastern Carpathians. Journal of Applied Ecology. https://doi.org/10.1111/1365-2664.14388
Teresa Berezowska-Cnota, Institute of Nature Conservation of the Polish Academy of Sciences
Websites: https://carpathianbear.pl/ , http://www.iop.krakow.pl/
Twitter: @CarpathianBs @INCPoland
Estación Biológica de Doñana – CSIC
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