Alberto Fernández-Gil

BROWN BEAR FOOD HABITS AT THE BORDER OF ITS RANGE: A LONG-TERM STUDY

Abstract Brown bear (Ursus arctos) food habits were examined from 1,500 fecal samples collected between 1974 and 2004 in the Cantabrian Mountains of northern Spain. The most important food items were graminoids and forbs in the spring, fleshy fruits (especially bilberries) in the summer, and hard mast in the autumn and winter (especially acorns). Animal matter also was consumed throughout the year. We found differences between 3 brown bear population nuclei within the Cantabrian population, which could be of enormous interest for habitat management. We also investigated how much interannual variation in different food items influenced our diet estimates. High fluctuations among years rather than values around a mean were inherent to some food items. However, for other items, the mean seems to be a reliable descriptor. We found that the additional years of data increased the coefficient of variation associated with some of our diet estimates and suggest the existence of directional changes in brown bear food habits that have been largely neglected. Although some studies suggest that diet is fixed and not changeable, our results show that long-term diet studies may reveal changes in habitat use patterns or habitat composition for brown bears and other wildlife species. Thus, incorporating diet studies into monitoring protocols can be helpful for designing and evaluating both current and future management actions.

Human behaviour can trigger large carnivore attacks in developed countries

The media and scientific literature are increasingly reporting an escalation of large carnivore attacks on humans in North America and Europe. Although rare compared to human fatalities by other wildlife, the media often overplay large carnivore attacks on humans, causing increased fear and negative attitudes towards coexisting with and conserving these species. Although large carnivore populations are generally increasing in developed countries, increased numbers are not solely responsible for the observed rise in the number of attacks by large carnivores. Here we show that an increasing number of people are involved in outdoor activities and, when doing so, some people engage in risk-enhancing behaviour that can increase the probability of a risky encounter and a potential attack. About half of the well-documented reported attacks have involved risk-enhancing human behaviours, the most common of which is leaving children unattended. Our study provides unique insight into the causes, and as a result the prevention, of large carnivore attacks on people. Prevention and information that can encourage appropriate human behaviour when sharing the landscape with large carnivores are of paramount importance to reduce both potentially fatal human-carnivore encounters and their consequences to large carnivores.

Long-term trends in food habits of a relict brown bear population in northern Spain: the influence of climate and local factors

SUMMARY 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-westernmostEuropeanpopulation.Thisfocused on the hyperphagic season, when bears gain the fat thatisessentialforwinterdormancyandreproduction. General climatic indicators were predictors of diet trends. Other variables potentially able to modify brownbearfoodhabitsatthelocalscalewereaccounted 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 fooditemsdecreasinglycontributedtobrownbeardiet, replacedbyincreasingcontributionsofsouthernfoods, which suggested that warmer temperatures might determine the occurrence of some food items in the diet of Cantabrian brown bears through effects on plant distribution and phenology. At the local scale, high cattle density in one of the study areas limited foodsourcesavailableforbrownbears.Importantfood sources for brown bears, such as heath-like Vaccinium formationsandold-growthoakforestintheCantabrian Mountains, require increased levels of protection.

Courtship of brown bears Ursus arctos in northern Spain: phenology, weather, habitat and durable mating areas

Abstract During 1988–2004 we made 297 non-systematic direct observations of free-ranging brown bears Ursus arctos in the Cantabrian Range of Spain, one of the southernmost and most endangered populations in Europe. Observations were distributed over the whole calendar year, with records in every month. We classified 23 observations as breeding behaviour (male-female close interactions). They occurred between 17 April and 12 June, but mainly from the second week of May to the first week of June, both included. Matings (N = 12) took place between 25 April and 12 June, with one in April, nine in May and two in June. These dates indicated that the mating season started earlier in the Cantabrian bear population than in other Euroasiatic and American bear populations. Breeding bears showed greater diurnal activity in cloudy and rainy weather than did non-breeding bears in the same period. Also, breeding bears used brush more often than forests and grasslands when compared with other bears in the same areas and periods. Some mating areas were used repeatedly in different breeding seasons (up to five years). The observed behaviour could be related to the small size of the bear population, the reduced and fragmented forest habitat and the high level of human disturbance characteristic of the Cantabrian Mountains. Reproductive strategies and mating systems, including the spatial and temporal patterns of breeding activities, are considered important scientific topics with implications for the implementation of suitable conservation measures, for the bears as well as for their habitat.

Conflict Misleads Large Carnivore Management and Conservation: Brown Bears and Wolves in Spain.

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.

Diet and habitat selection in Cantabrian Capercaillie (Tetrao urogallus cantabricus): ecological differentiation of a rear-edge population

Cantabrian capercaillie Tetrao urogallus cantabricus is a peripheral population with distinctive phenotypic, biogeographic, and genetic characteristics. Hence, the population may also show substantial ecological differentiation associated with its habitat in purely deciduous forests. We assessed seasonal diet selection, small-scale habitat selection, and patterns of trophic niche width in Cantabrian capercaillie over two years. Diet was found to be a driver of small-scale habitat selection, a result consistent with previous studies of stand-scale habitat selection. Diet and habitat selection showed the importance of beech Fagus sylvatica, holly Ilex aquifolium, bilberry Vaccinium myrtillus, and ferns in Cantabrian capercaillie’s resource selection. Conversely, the abundant oaks Quercus petraea, birches Betula pubescens, and heaths Erica sp. were used below their availability. The reliance on bilberry appears as a unifying characteristic between central and peripheral capercaillie populations. Cantabrian capercaillie showed stronger reliance on understory resources than range-central populations. It also showed wider trophic niche and higher specialization of feeding events. Trophic niche patterns and reliance on ground resources indicated a marked ecological differentiation, which stresses the need for local data and specific conservation actions.

Demographic status and genetic tagging of endangered capercaillie in NW Spain.

Counting rare and elusive animals and evaluating their demographic status, are fundamental yet challenging aspects of population ecology and conservation biology. We set out to estimate population size (Nc), genetic effective population size (Ne gen), sex ratio, and movements based on genetic tagging for the threatened Cantabrian capercaillie. We used 9 microsatellite loci to genotype 134 droppings collected at 34 display areas during the breeding season. Using genetic capture-mark-recapture, we estimated 93 individuals (Nc, 95% CI: 70–116) in an area of about 500 km2, with sex ratio biased towards males (1∶1.6). Estimated Ne gen (35.5) was 38% of Nc, notably higher than the published average in wild populations. This capercaillie population is small and well within concern in terms of population viability. By genetic tagging, we detected mostly short movements; just a few males were recaptured between contiguous display areas. Non-invasive surveys of endangered populations have a great potential, yet adequate sample size and location are key to obtain reliable information on conservation status.

Are Cantabrian brown bears recovering

Abstract The Cantabrian brown bear (Ursus arctos) population of northwest Spain has been monitored since 1982. Population trends have been estimated using counts of females with cubs-of-the-year (hereafter, FCUB). A population viability analysis found a mean annual decrease of 4–5% for 1982–95, but with a stabilizing or even slightly increasing trend in the early 1990s. A recent paper in Ursus concluded that the population was “recovering,” with a 7.5% annual increase, based on the FCUB index for 1994–2004. We show several factors limit the interpretation of an increasing trend based on the FCUB data. First, data collection was not systematic, nor were spatial sampling and sampling effort sufficiently accounted for, leading to an arbitrary election of the period to estimate FCUB trends. Second, data sets did not meet probabilistic analytical requirements. Third, the assumption that the FCUB trend, albeit positive, directly reflects the population trend was not justified. In addition, we argue that alternative hypotheses explaining FCUB trends should have been presented, particularly because of the absence of a correlation between population and range increases. Altogether, we call for caution when analyzing data about critically endangered populations like that of brown bears in the Cantabrian Mountains.

Estimating the population size of the endangered Cantabrian brown bear through genetic sampling

The Cantabrian brown bear Ursus arctos population can be seen as a paradigm in conservation biology due to its endangerment status and genetic uniqueness. Therefore, the need to obtain basic demographic data to inform management actions for conservation is imperative. Despite this, empirical data on the size and trends of the Cantabrian bear population are scarce. Here we present the first estimates of population size (Nc) and effective population size (Ne) of the whole Cantabrian brown bear population. We genotyped 270 non-invasive samples collected during 2006 throughout the entire range of the population and subsequently identified 130 individuals. Different model estimators of Nc based on capture—markrecapture (CMR) procedures were compared. The average for the best three models (Mh Chao, Mh Darroch and CAPWIRE TIRM) yielded a total estimate of Nc = 223 individuals (CI95% = 183–278) and Ne 50 (CI95% = 36–75) providing an Ne / Nc ratio of 0.22. Estimates for the two subpopulations commonly recognized in the Cantabrian range were Nc = 203 (CI95% = 168–260) and Ne = 47 (CI95% = 36–70) for the western subpopulation and Nc = 19 (CI95% = 12–40) and Ne= 9 (CI95% = 8–12) for the eastern subpopulation. These data suggest that the Cantabrian brown bear population has increased recently, mainly in the western subpopulation, after a long period of decline and isolation which lead to the split of the population at the beginning of the 20th century. Population sizes in the early 1990s were thought to be only 60 individuals for the western subpopulation and 14 individuals in the eastern one. The efforts to improve conservation policies made since then have probably contributed, to some extent, to the population increase during the last couple of decades.

Histological, chemical and behavioural evidence of pedal communication in brown bears

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.