Carlos Bautista, Member: Human-Bear Conflict Expert Team, IUCN Bear Specialist Group
Eloy Revilla, Doñana Biological Station (EBD-CSIC)
Javier Naves, Doñana Biological Station (EBD-CSIC)
Nuria Selva, Member: European Brown Bear Expert Team, IUCN Bear Specialist Group

Food matters

It matters to you, to the sparrow sitting on the park bench, and to the bear roaming the forest. Those of us living close to supermarkets do not worry much about how many nuts the forest produced. However, times of feast and famine are not rare in nature and fluctuations in primary production greatly affect consumers’ communities and their interaction across trophic levels (Ostfeld and Keesing 2000). For instance, a year of low seed production is followed by a decrease in the abundance of mice and other seed consumers which, in turn, affects the density of generalist predators eating rodents (Ostfeld and Keesing 2000, McShea 2008). Yet, many species of animals are adaptive. In human-dominated landscapes they may compensate for shortages of natural food by utilizing human-derived products, such as crops or livestock (Woodroffe et al. 2005). As a result, the temporal lack of natural food may increase human-wildlife interactions, and cause conflict situations (e.g., Artelle et al. 2016).

Why is food important?

Because conflicts arising from wildlife damage to crops and livestock may impose considerable costs for humans and animals, the affected persons can suffer significant economic and sentimental losses, and in response, some retaliate against wildlife. In order to prevent these losses and to protect wildlife, managers and researchers make big efforts to understand how, when, where, and why these damages occur. Some studies have observed correlates with damage occurrence, such as the density of wildlife and humans, husbandry practices, and strategies to manage wildlife and damage (Woodroffe et al. 2005). Lately, some studies have started to investigate the role of landscape features and the availability of natural and anthropogenic food resources (e.g., Suryawanshi et al. 2013). However, the connection between availability of food resources and damage seems to be inconclusive: while some studies have found lower damage at times of more food (Suryawanshi et al. 2013), others suggest that greater resource availability may lead to increased occurrence of wildlife-caused damage (Treves et al. 2004, Karanth et al. 2013).

Brown bear scat full of beechnuts (Fagus sylvatica) in the Polish Carpathians. Photo credit: Carpathian Brown Bear Project.

Brown bear scat full of beechnuts (Fagus sylvatica) in the Polish Carpathians.
Photo credit: Carpathian Brown Bear Project.

Does food influence conflict situations, and if so, how much?

To answer these questions, we started a project aimed at quantifying the influence of the availability of natural food resources on the occurrence of wildlife-caused damage. Specifically, we use the brown bear (Ursus arctos) as a model species and focus on food habits and damage across different brown bear populations. The project is entitled “Does food matter? Assessing the role of pulses in resource availability as a driver of temporal variation in brown bear damage occurrence” and is based on an international cooperation between the Institute of Nature Conservation of the Polish Academy of Sciences (IOP PAN) and the Doñana Biological Station of the Spanish National Research Council (EBD-CSIC). The project is funded by the National Science Centre in Poland (UMO-2017/25/N/NZ8/02861) and will be conducted in 2018-2021.
We aim to assess the relationship between the temporal variation in bear dietary composition and occurrence of bear-caused damage. It has been shown that scat analysis can capture differences in the relative availability of food resources (e.g., Ciucci et al. 2014). We hypothesize that variation in the consumption of different natural foods across years is a good predictor of bear-caused damage. For instance, in temperate Europe, hard mast (acorns and beechnuts) is a critical food resource for brown bears before hibernation (Naves et al. 2006, Ciucci et al. 2014). Accordingly, we expect that during hyperphagia, poor hard mast crops may prompt bears to shift their diet and raid fruit plantations and apiaries.

Beehives damaged by brown bear in the Polish Carpathians (note outline of pawprint on box). Bears presumably turn to these human-related food sources, which can be rich by risky, when natural foods are less plentiful. Photo credit: Carpathian Brown Bear Project.

Beehives damaged by brown bear in the Polish Carpathians (note outline of pawprint on box). Bears presumably turn to these human-related food sources, which can be rich by risky, when natural foods are less plentiful. Photo credit: Carpathian Brown Bear Project.

Beehives damaged by brown bear in the Polish Carpathians. Bears presumably turn to these human-related food sources, which can be rich by risky, when natural foods are less plentiful. Photo credit: Carpathian Brown Bear Project.

Beehives damaged by brown bear in the Polish Carpathians. Bears presumably turn to these human-related food sources, which can be rich by risky, when natural foods are less plentiful. Photo credit: Carpathian Brown Bear Project.

The big picture

We plan to look for dietary data on bear populations located in the temperate regions of Asia, Europe and North America. To capture the variation in the proportion of foods consumed by bears, we will seek data that span a minimum of 4 years. Additionally, we will also search for data on reported and verified bear damage matching the same data period and area. We will add the data obtained from other areas to our main dataset with already 3000 scats and over 5000 verified damages in the Cantabrian and Carpathian populations.
Specifically, we will model the number of verified damages as a response of the average frequency of different food categories at seasonal and annual scales. We will divide the bear damages in 3 categories (livestock, apiaries, crops) and analyze them as separate response variables (see Bautista et al. 2017). To explore the influence of different ingested foods, we will calculate the frequency of 5 categories of natural foods (green vegetation, fleshy fruits, hard mast, invertebrates and vertebrates) and analyze each category as a separate explanatory variable. Finally, we aim to include in all the models other potential sources of temporal variation, such as density of bears and humans, livestock and apiary abundance, and the economic effort invested in prevention. This will allow us to quantify the relative importance of resource consumption by bears on the amount of damage they cause.

Contact us!

If you are interested in our study and think you can contribute with suitable data and/or you would like further details about our project, we kindly invite you to contact us. We really hope that together we can try to understand a bit better the factors underlying bear damages and, thus, improve coexistence between humans and bears.

Literature Cited
Artelle, K.A., S.C. Anderson, J.D. Reynolds, A.B. Cooper, P.C. Paquet, and C.T. Darimont. 2016. Ecology of conflict: marine food supply affects human-wildlife interactions on land. Scientific Reports 6: 25936.
Bautista, C., J. Naves, E. Revilla, N. Fernández, J. Albrecht, A.K. Scharf, R. Rigg, A.A. Karamanlidis, K. Jerina, D. Huber, S. Palazón, R. Kont, P. Ciucci, C. Groff, A. Dutsov, J. Seijas, P.I. Quenette, A. Olszańska, M. Shkvyria, M. Adamec, J. Ozolins, M. Jonozovič, and N. Selva. 2017. Patterns and correlates of claims for brown bear damage on a continental scale. Journal of Applied Ecology 54:282–292.
Ciucci, P., E. Tosoni, G. Di Domenico, F. Quattrociocchi and L. Boitani. 2014. Seasonal and annual variation in the food habits of Apennine brown bears, central Italy. Journal of Mammalogy 95:572–586.
Karanth, K.K., A.M. Gopalaswamy, P.K. Prasad, and S. Dasgupta. 2013. Patterns of human-wildlife conflicts and compensation: Insights from Western Ghats protected areas. Biological Conservation 166:175–185.
McShea, W.J. 2008. The Influence of Acorn Crops on Annual Variation in Rodent and Bird Populations. Ecology 81:228–238.
Naves, J., A.Fernández-Gil, C. Rodríguez, and M. Delibes. 2006. Brown bear food habits at the border of its range: a long-term study. Journal of Mammalogy 87:899–908.
Ostfeld, R.S. and F. Keesing. 2000. Pulsed resources and community dyamics of consumers in terrrestrial ecosystems. Trends in Ecology and Evolution 15:232–237.
Suryawanshi, K.R., Y.V. Bhatnagar, S. Redpath, and C. Mishra. 2013. People, predators and perceptions: Patterns of livestock depredation by snow leopards and wolves. Journal of Applied Ecology 50:550–560.
Treves, A., L. Naughton-Treves, E.K. Harper, D.J. Mladenoff, R.A. Rose, T.A. Sickley, and A.P. Wydeven. 2004. Predicting Human-Carnivore Conflict: A Spatial Model Derived from 25 Years of Data on Wolf Predation on Livestock. Conservation Biology 18:114–125.
Woodroffe, R., S. Thirgood and A. Rabinowitz. 2005. Poeple and wildlife: Conflict or coexistence. Cambridge University Press, New York.

Carlos Bautista

Member: Human-Bear Conflict Expert Team, IUCN Bear Specialist Group
Institute of Nature Conservation
Polish Academy of Science
Krakow, Poland
Email: carlosbautistaleon@gmail.com

Eloy Revilla

Doñana Biological Station (EBD-CSIC)
Spanish National Research Council
Seville, Spain
Email: revilla@ebd.csic.es

Javier Naves

Doñana Biological Station (EBD-CSIC)
Spanish National Research Council
Seville, Spain
Email: jnaves@ebd.csic.es

Nuria Selva

Member: European Brown Bear Expert Team, IUCN Bear Specialist Group
Institute of Nature Conservation
Polish Academy of Science
Krakow, Poland
Email: nuriaselva@gmail.com

originally published in International Bear News 2018 Fall Vol. 27 No. 3 on pages 47-48