DEPARTMENT OF BIOLOGICAL AND ENVIRONMENTAL SCIENCES IS PREY DEFAUNATION A POTENTIAL CAUSE OF CARNIVORE RANGE LOSS AND EVENTUAL EXTINCTION? Hanna Svensson Degree project for Master of Science (120 hec) with a major in Biology BIO717, Degree project in Evolutionary and behavioural ecology, 60 hec Second cycle Semester/year: Autumn 2017 - Spring 2018 Supervisor: Sören Faurby, Department of Biological & Environmental Sciences Examiner: Bengt Oxelman, Department of Biological & Environmental Sciences Table of contents Abstract ............................................................................................................................................ 3 Introduction ...................................................................................................................................... 3 Aim of the study ............................................................................................................................... 5 Method ............................................................................................................................................. 5 Results .............................................................................................................................................. 7 Defaunation ................................................................................................................................ 10 Body mass relation to prey loss .................................................................................................. 18 Discussion ...................................................................................................................................... 21 Prey loss ..................................................................................................................................... 21 Range overlap ............................................................................................................................. 21 Could this be used as a new conservation strategy? ................................................................... 22 Conclusion ..................................................................................................................................... 22 Acknowledgement.......................................................................................................................... 23 Popular science summary ............................................................................................................... 23 References ...................................................................................................................................... 23 Supplementary information ............................................................................................................ 26 2 Abstract Defaunation, the loss of animals from ecological communities, have been emphasized as a likely threat to the conservation of carnivores. However, not much is known about the potential threat that defaunation presents to terrestrial carnivores that feed on mammals. Therefore, the aim was to explore this threat and if it’s a potential cause of carnivore range loss and extinction. A new diet database was generated in collaboration with Owen Middleton for the terrestrial members of the order Carnivora having mammals as a primary prey item, resulting in 20170 diet records collected from 566 published literature sources. For Felids (cat species) an existing diet database was used. To estimate the potential threat to carnivores from the loss of their prey, overlap range maps of predator and their primary and secondary prey species were created. These were compared to maps where prey species classified as vulnerable or worse by the IUCN were removed. Two carnivores experienced a 100% loss of their primary prey range, Striped Hyaena (Hyaena hyaena) and Sechuran Fox (Lycalopex sechurae). The Brown bear (Ursus arctos) with 48% loss and the Dhole (Cuon alpinus) with 46% loss experienced the second highest loss. It’s important to remember that these ranges only display the mammalian prey species of the carnivores and not the entire diet. The Striped Hyaenas diet consists of 88,76% of mammals compared to the 60,90% of the Sechuran Fox and 93,13% of the Dhole’s diet. For the omnivorous Brown bear only 38,51% of its diet is mammalian and it is therefore not as affected by the primary prey range loss as strict carnivores. Defaunation of primary prey will probably result in carnivore range loss and can be a cause for future extinctions. Sammanfattning Defaunation, förlusten av djur från ekologiska samhällen har betonats som ett troligt hot mot bevarandet av rovdjur. Men inte mycket är känt om det potentiella hot som defaunation utgör för marklevande rovdjur som livnär sig på däggdjur. Därför var syftet att undersöka detta hot och om det är en potentiell orsak till minskat utbredningsområde och utrotning av rovdjur. I samarbete med Owen Middleton skapades en ny dietdatabas för de landlevande medlemmarna i ordningen Carnivora som har däggdjur som primärt bytesdjur, vilket resulterade i 20170 dietregistreringar hämtade ifrån 566 publicerade litteraturkällor. För kattdjur användes en befintlig dietdatabas. För att uppskatta det potentiella hotet mot rovdjur från förlusten av sitt bytesdjur, skapades överlappskartor för rovdjur och deras primära och sekundära bytesdjursarter. Dessa jämfördes med kartor där bytesdjur som är klassificerade som sårbara eller värre av IUCN togs bort. Två rovdjur hade en 100% förlust av utbredningsområde för deras primära bytesdjur, Randig hyena (Hyaena hyaena) och Sechuran räv (Lycalopex sechurae). Brunbjörn (Ursus arctos) med en förlust av 48% och Dhol (Cuon alpinus) med 46% hade den näst högsta förlusten. Det är viktigt att komma ihåg att dessa utbredningsområden endast visar delen av däggdjur i rovdjurens diet och inte hela dieten. Randig hyenas diet består till 88,76% av däggdjur jämfört med Sechuran rävs 60,90% och Dhols 93,13%. Den allätande Brunbjörnens diet består endast till 38,51% av däggdjur och är därför inte lika påverkad av minskade utbredningsområden hos dess primära bytesdjur som strikta rovdjur är. Defaunation av primärt bytesdjur kommer troligen att leda till minskning av rovdjurens utbredningsområden och kan orsaka framtida utrotningar. Introduction Right now, we’re living in an ongoing global mass extinction (Barnosky et al., 2011) with biodiversity severely threatened by human activity, most of which are linked to mankind’s expanding ecological footprint, invading natural habitats for food production and living space, driving climate change and polluting the world’s oceans and rivers. Secondary threats come from 3 alien invasive species introductions (Mooney and Cleland, 2001; Johnson, 2006) and any other alterations to functional ecosystems. The International Union for Conservation of Nature (IUCN) have assessed the status for all species where data were available. The IUCN Red List is “widely recognized as the most comprehensive, objective global approach for evaluating the conservation status of plant and animal species.” (IUCN, 2017). Mammal decline is a global issue with almost one-quarter of the species (22.2 %) globally threatened or extinct, representing 1,219 species (Figure 1) (IUCN, 2018). Ceballos et al. (2017) found that of 177 mammals all species had lost 30% or more of their geographic ranges and more than 40% of the species have experienced severe population declines (>80% range loss). Figure 1. Proportion of mammal species in different threat categories, graph from IUCN (2018) The geographic range of species are often composed of numerous local populations interacting. Range loss occurs when local populations disappear from their natural habitat, leading to species becoming extirpated or “locally extinct”. Concentrating on range loss and the extirpation of these local populations can help guide and prioritize conservation efforts before population size drop to critical levels (Caughley, 1994). Even though a species is still common globally, studying range loss can identify where ecosystems are losing local populations of that species (Ceballos and Ehrlich, 2002) and thereby help find tools to prevent further loss before the species become 4 globally threatened. Increases in species extinction risk are typically linked to the loss of individual populations and associated declines in geographical range (Ceballos and Ehrlich, 2002). Recently several carnivores have experienced substantial population declines, geographic range reductions, and fragmentation of their habitats (Morrison et al., 2007; Ceballos et al., 2015). 61% of large carnivore species (≥ 15 kg) are listed by the IUCN as near threatened, vulnerable or worse and are at risk of local or global extinction (Ripple et al., 2014). The conservation of large carnivores is important for maintaining the structure and function of diverse ecosystems (Ripple et al., 2014). If one or several parts of the ecosystem is affected or changed the consequences could be catastrophic. Understanding the importance of predator–prey interactions for species diversity and community composition is a central theme in ecology. Sandom et al. (2013) discovered strong associations between predator and prey richness in a bottom-up direction at global and regional scales, predator richness was highly linked to prey richness. Krantz (1970) claim that prey diversity loss may partly account for the extinction of large carnivores. Healthy ecosystems depend on predators