Javier Naves - Academia.edu (original) (raw)

Papers by Javier Naves

Proceedings of the Royal Society B: Biological Sciences, 2021

Human encroachment into natural habitats is typically followed by conflicts derived from wildlife... more Human encroachment into natural habitats is typically followed by conflicts derived from wildlife damage to agriculture and livestock. Spatial risk modelling is a useful tool to gain the understanding of wildlife damage and mitigate conflicts. Although resource selection is a hierarchical process operating at multiple scales, risk models usually fail to address more than one scale, which can result in the misidentification of the underlying processes. Here, we addressed the multi-scale nature of wildlife damage occurrence by considering ecological and management correlates interacting from household to landscape scales. We studied brown bear ( Ursus arctos ) damage to apiaries in the North-eastern Carpathians as our model system. Using generalized additive models, we found that brown bear tendency to avoid humans and the habitat preferences of bears and beekeepers determine the risk of bear damage at multiple scales. Damage risk at fine scales increased when the broad landscape cont...

Scientific Reports, 2019

The increasing trend of large carnivore attacks on humans not only raises human safety concerns b... more The increasing trend of large carnivore attacks on humans not only raises human safety concerns but may also undermine large carnivore conservation efforts. Although rare, attacks by brown bears Ursus arctos are also on the rise and, although several studies have addressed this issue at local scales, information is lacking on a worldwide scale. Here, we investigated brown bear attacks (n = 664) on humans between 2000 and 2015 across most of the range inhabited by the species: North America (n = 183), Europe (n = 291), and East (n = 190). When the attacks occurred, half of the people were engaged in leisure activities and the main scenario was an encounter with a female with cubs. Attacks have increased significantly over time and were more frequent at high bear and low human population densities. There was no significant difference in the number of attacks between continents or between countries with different hunting practices. Understanding global patterns of bear attacks can help...

Journal of Applied Ecology, 2016

Journal of Mammalogy, 2006

Environmental Conservation, 2007

Relict endangered populations may be especially vulnerable to the effects of climate change. A da... more Relict endangered populations may be especially vulnerable to the effects of climate change. A data series for the period 1974–2003 was used to examine shifts in brown bear Ursus arctos food habits in its south-westernmost European population. This focused on the hyperphagic season, when bears gain the fat that is essential for winter dormancy and reproduction. General climatic indicators were predictors of diet trends. Other variables potentially able to modify brown bear food habits at the local scale were accounted for by considering two areas where local conditions changed in different ways during the study period. General climatic indicators such as temperature and the winter North Atlantic Oscillation index were good predictors of some diet trends, although local factors seemed to modulate the potential response of food habits to recent climate change. Boreal and temperate food items decreasingly contributed to brown bear diet, replaced by increasing contributions of southern ...

Conservation Biology, 2003

The brown bear (Ursus arctos) is one of the Spanish mammaIs in danger of extinction. Due to its h... more The brown bear (Ursus arctos) is one of the Spanish mammaIs in danger of extinction. Due to its high mobility and behaviour it is extremely difficult to keep sign of each individual of the popoIation. For this reason, a set of seasonal maps of the available trophic resources has been developed to allocate bear activity. These maps are the product of data base developed with a Geographical Infonnation System. Our study area (176 km2) is located in the Somiedo Natural Park (Asturias, NW Spain). The map set has allowed to restriet the sampling bear activity to the selected enviroomentaI units. These selected areas coostitute 54.58% of the totaI of the area of study during Spring, 12.17% during Summer and 28.23% during Autumn. These maps have allowed a selective sampling (trails) of key areas with a remarkable increase in the number of bear signs: an average of one point with sings of bear activity every 2.73 km covered. This result has been supposed to increase by six the effectiveness...

Ecological Monographs, 1998

The status of the brown bear (Ursus arctos) in Spain has suffered a dramatic decline during the l... more The status of the brown bear (Ursus arctos) in Spain has suffered a dramatic decline during the last centuries, both in area and numbers. Current relict populations are suspected to be under immediate risk of extinction. The aim of our model is to attain an understanding of the main processes and mechanisms determining population dynamics in the Cordillera Cantabrica. We compile the knowledge available about brown bears in the Cordillera Cantabrica, northern Spain, and perform a population viability analysis (PVA) to diagnose the current state of the population and to support current management. The specially constructed simulation model, based on long-term field investigations on the western brown bear population in the Cordillera Cantabrica, includes detailed life history data and information on environmental variations in food abundance. The method of individual-based modeling is employed to simulate the fate of individual bears. Reproduction, family breakup, and mortalities are modeled in annual time steps under the influence of environmental variations in food abundance, mortality rates, and reproductive parameters. In parallel, we develop an analytical model that describes the mean behavior of the population and that enables us to perform a detailed sensitivity analysis. We determine current population parameters by iterating the model with plausible values and compare simulation results with the 1982-1995 time pattern of observed number of females with cubs of the year. Our results indicate that the population suffered a mean annual decrease of ϳ4-5% during the study period, 1982-1995. This decrease could be explained by a coincidence of high poaching pressure with a series of climatically unfavorable years during the period 1982-1988. Thereafter, population size probably stabilized. We estimate that the population currently consists of 25 or 26 independent females and a total of 50-60 individuals. However, our viability analysis shows that the population does not satisfy the criterion of a minimum viable population if mortalities remain at the level of the last few years of 1988-1995. The ''salvation'' of at least one independent female every three years is required. The population retains relatively high reproductive parameters, indicating good nutritive conditions of the habitat, but mortality rates are higher than those known in other brown bear populations. The most sensitive parameters, adult and subadult mortality of females, form the principal management target. Our model shows that the series of females with cubs contains valuable information on the state of the population. We recommend monitoring of females with cubs as the most important management action, both for collecting data and for safeguarding the most sensitive part of the population.

PeerJ

Chemical communication is important for many species of mammals. Male brown bears, Ursus arctos, ... more Chemical communication is important for many species of mammals. Male brown bears, Ursus arctos, mark trees with a secretion from glands located on their back. The recent discovery of pedal glands and pedal-marking at a site used for tree-rubbing led us to hypothesize that both types of marking form part of a more complex communication system. We describe the patterns of chemical communication used by different age and sex classes, including differences in the roles of these classes as information providers or receivers over four years at a long-term marking site. Using video recordings from a camera trap, we registered a total of 285 bear-visits and 419 behavioral events associated with chemical communication. Bears visited the site more frequently during the mating season, during which communication behaviors were more frequent. A typical visit by male bears consisted of sniffing the depressions where animals pedal mark, performing pedal-marking, sniffing the tree, and, finally, r...

Proceedings of the 5th European Congress of Conservation Biology

PLOS ONE

Demographic evolution of the brown bear population, identification of corridors of communication ... more Demographic evolution of the brown bear population, identification of corridors of communication between subpopulations and analysis of the damages caused by the species to agriculture and livestock in Asturias Ref.

Biodiversity and Conservation

FEDER). Thanks to those managers from the Spanish regional administrations that answered our info... more FEDER). Thanks to those managers from the Spanish regional administrations that answered our information requests. Fernando Jubete, Rubén Portas and Juan Ángel de la Torre helped us compiling and interpreting lethal management data.

Scientific reports, Jan 21, 2017

Most mammals rely upon scent for intraspecific communication. As most bear species have large hom... more Most mammals rely upon scent for intraspecific communication. As most bear species have large home ranges and are non-territorial, scent deposit while walking could be an effective way to communicate with conspecifics. Here, we investigate the existence of pedal glands in brown bears and their role in chemical communication from a histological, biochemical and behavioural perspective. We found eccrine glands in footpads, and prominent apocrine and sebaceous glands in the interdigital, metacarpal and metatarsal skin sections. Pedal scent contained 26 compounds including carboxylic acids, important constituents of mammalian secretions. Six of these compounds were exclusive for males. Finally, we describe a specific marking gait recorded in the field, mostly performed by males. Our study supports the existence of chemical communication through pedal marking in brown bears and suggests sex-coding potential of pedal scent. Chemical signaling is a widespread mode of communication amongst the vast majority of organisms, both terrestrial and aquatic 1. Among mammals, odours play a key role in communication, with chemical signaling used to inform about identity, sex, territorial borders, social status, reproductive state or group membership 2, 3. Apart from the prevalent chemical features of urine and faeces, mammal skin secretions offer a great potential for chemical communication, with many species showing specialized scent glands that are the main source of secretions in scent marking 4-7. Well known is the use of scent marking at communal latrines by badgers (Meles meles) and other mustelid species, which have anal glands used for specific squat-marking 8. Marking with subcaudal, chin, foot and ventral glands, and through scratching and rolling has also been recorded 7, 8. The understanding of the mechanisms behind the detection of scents and how the scent stimuli is reconstructed into scent maps used by animals in their environment has greatly advanced, but the world of odours and the way they are perceived still require a great deal more research and experimentation 9. The skin of mammals typically presents three types of glandular structures: holocrine sebaceous glands, apocrine sweat and eccrine sweat glands 4, 10. Sebaceous glands are evenly distributed over the body. They coat hair with sebum as it grows and are usually anatomically near an apocrine gland 11. Apocrine sweat glands, opening to follicles, are primarily observed in hairy skin 12 , while eccrine sweat glands secreting directly to skin surface via pores tend to be confined to specific regions, such as carnivores' footpads 5 or friction surfaces of hands, feet and tails of prosimians, monkeys and apes 11. These basic types of glands may associate in more complex structures (e.g. sacs) often located in specific areas of the skin. Finally, the presence of mammalian scent glands is often linked to typical behavioural patterns of scent marking 4-6, 13. Therefore an in-depth examination of the existence of scent glands is the first step to disentangle chemical communication. Most areas containing sebaceous and sweat glands can be involved in scent production and synthesize different odoriferous molecules 14. The secretions of these glands can be ultimately affected by bacterial fermentation,

Scientific Reports, 2017

A mistake occurred due to a failure in the conversion of the variable "species" from integer to a... more A mistake occurred due to a failure in the conversion of the variable "species" from integer to a categorical (factor) variable. We have updated the tables with 'species' as a factor (Extended Data Tables below). It is important to state that the essence of our results and conclusions do not change from those presented in the article. Additionally, we took opportunity of this corrigendum to explore the variation in the group composition (party size) of humans that suffered large carnivore attack over time and across species. We simplified our response categorical variable 'group composition' into two categories, i.e., 'victim alone' and 'victim in a party' (binary coded variable). We conducted this analysis using a two-level categorical approach (binomial family in R) instead of using the previous multinomial approach. This change does not affect the results or conclusions of our analysis, as reported in the article, but is a simplification. The correct Extended Data Tables 1, 2, 3 and 4 appear below as Table 1, 2, 3 and 4 respectively.

Proceedings of the Royal Society B: Biological Sciences, 2016

Understanding what factors drive fluctuations in the abundance of endangered species is a difficu... more Understanding what factors drive fluctuations in the abundance of endangered species is a difficult ecological problem but a major requirement to attain effective management and conservation success. The ecological traits of large mammals make this task even more complicated, calling for integrative approaches. We develop a framework combining individual-based modelling and statistical inference to assess alternative hypotheses on brown bear dynamics in the Cantabrian range (Iberian Peninsula). Models including the effect of environmental factors on mortality rates were able to reproduce three decades of variation in the number of females with cubs of the year ( Fcoy ), including the decline that put the population close to extinction in the mid-nineties, and the following increase in brown bear numbers. This external effect prevailed over density-dependent mechanisms (sexually selected infanticide and female reproductive suppression), with a major impact of climate driven changes i...

PLOS ONE, 2016

Large carnivores inhabiting human-dominated landscapes often interact with people and their prope... more Large carnivores inhabiting human-dominated landscapes often interact with people and their properties, leading to conflict scenarios that can mislead carnivore management and, ultimately, jeopardize conservation. In northwest Spain, brown bears Ursus arctos are strictly protected, whereas sympatric wolves Canis lupus are subject to lethal control. We explored ecological, economic and societal components of conflict scenarios involving large carnivores and damages to human properties. We analyzed the relation between complaints of depredations by bears and wolves on beehives and livestock, respectively, and bear and wolf abundance, livestock heads, number of culled wolves, amount of paid compensations, and media coverage. We also evaluated the efficiency of wolf culling to reduce depredations on livestock. Bear damages to beehives correlated positively to the number of female bears with cubs of the year. Complaints of wolf predation on livestock were unrelated to livestock numbers; instead, they correlated positively to the number of wild ungulates harvested during the previous season, the number of wolf packs, and to wolves culled during the previous season. Compensations for wolf complaints were fivefold higher than for bears, but media coverage of wolf damages was thirtyfold higher. Media coverage of wolf damages was unrelated to the actual costs of wolf damages, but the amount of news correlated positively to wolf culling. However, wolf culling was followed by an increase in compensated damages. Our results show that culling of the wolf population failed in its goal of reducing damages, and suggest that management decisions are at least partly mediated by press coverage. We suggest that our results provide insight to similar scenarios, where several species of large carnivores share the landscape with humans, and management may be reactive to perceived conflicts.