José M. Fedriani

Niche relations among three sympatric Mediterranean carnivores

Abstract Previous studies carried out in the Doñana National Park reported that red foxes (Vulpes vulpes) were killed by Iberian lynxes (Lynx pardinus), whereas similar-sized Eurasian badgers (Meles meles) were not. Therefore, we predicted that fox would avoid lynx predation risk by niche segregation whereas we did not expect such a segregation between badger and lynx. As an approach for evaluating our predictions, we compared their diet, activity patterns, and habitat use in an area of Doñana where the three carnivores are sympatric. Lynxes preyed almost uniquely on European rabbits (Oryctolagus cuniculus), and though badgers and foxes were omnivorous, rabbits also were a major prey, resulting in high overlaps throughout the year. However, badgers preyed largely on small rabbits, whereas lynxes and foxes preyed mainly on medium-sized rabbits. There were also interspecific differences in activity patterns. Maximum levels of activity among lynxes were during sunrise and dusk (49–67%). Foxes were most active during dusk and night (34–67%), and badgers were mainly nocturnal (53–87%). Though there were seasonal differences in the amount of activity of each species, specific activity patterns changed little throughout the year. There was a strong difference in annual habitat use by the three species (P < 0.0001). Lynxes used mainly the Mediterranean scrubland during both the active (PMAX) and the resting (PMIN) periods. During PMIN, foxes used the Mediterranean scrubland intensively (40% of locations on average), but during PMAX, they used the pastureland much more intensively despite this habitat being poorer in their main prey (rabbits). As a consequence, foxes and lynxes exhibited segregation in their habitat use during the active period. Badgers also used the Mediterranean scrubland intensively, especially during PMIN. There were no seasonal differences in habitat use for lynx and fox, but there was for badgers (P < 0.015). Within the study area, the three species selected habitat suggesting they were sensitive to factors such as vegetation and prey abundance. However, in general, carnivore habitat use did not correlate with rabbit abundance. We propose that foxes avoided lynxes by using, during activity, habitats not frequented by lynxes, and that a low predation risk associated with the distinctive foraging mode of badgers may facilitate its coexistence with other carnivores.

Spatial relationships between Iberian lynx and other carnivores in an area of south-western Spain

1. Spatial relationships between Iberian lynx and other carnivores were studied by radio-tracking and/or track censusing in two adjacent areas of Donana (south-western Spain). 2. Both radio-tracking and track censusing showed that lynx were restricted to an undisturbed area of Pistacia lentiscus shrubs called Matasgordas. Minimum and maximum lynx density in Matasgordas were estimated as 0.55 and 0.75 ind. km -2 . 3. Egyptian mongoose tracks were mainly detected outside Matasgordas (83% of tracks), European badger tracks were detected most often inside Matasgordas (76% of tracks), and red fox tracks were frequently detected both outside (54%) and inside (46%) Matasgordas. Surveys of tracks and faeces undertaken in other 14 areas where P. lentiscus shrubs also dominated corroborated the census data obtained inside and outside Matasgordas. 4. Trapping and radio-tracking of mongooses and common genets indicated that both species avoided use of Matasgordas. They were almost exclusively trapped (24 out of 25 mongooses and all of 11 genets) and mainly radio-located (94.5% and 95.4% of times, for mongooses and genets, respectively) in the areas of P. lentiscus shrubs situated outside Matasgordas. Their densities were estimated as 0.2 and 0.03 ind. km -2 inside, and as 2.0 and 0.7 ind. km -2 outside Matasgordas for mongooses and genets, respectively. 5. Lynx may kill mongooses, genets, and foxes ; thus, the avoidance of Matasgordas by smaller carnivores (mongooses and genets) could be related to the risk of lynx predation. It is suggested that the decline of the lynx in the Donana area may have caused the increase in the population size of smaller, previously rarer carnivores. 6. The true relationship between lynx and foxes remains unclear, and badgers were apparently indifferent to lynx presence or absence.

Seed Dispersal in the Iberian Pear, Pyrus bourgaeana: A Role for Infrequent Mutualists

Abstract: Seed dispersal by animals is a key interaction, with effects on the population ecology and evolution of many plant lineages. Despite the fact that infrequent seed dispersers can potentially provide important services to plant populations, little attention has been paid so far to scarce mutualists. We assessed different aspects of quantity and quality of seed dispersal from fruit removal to seed germination in the Iberian pear, Pyrus bourgaeana, finding that fruit consumers markedly differed in the nature of their interaction with the tree. Whereas the abundant rodents, rabbits, and deer damaged all seeds eaten, the uncommon carnivores badger and fox and the abundant boars dispersed a large fraction of ingested seeds as viable propagules, acting as legitimate seed dispersers. Despite low rates of visitation by badgers to fruiting trees, they transported more viable seeds than the abundant boars, due to better seed treatment and a higher feeding rate on pears. Seed dispersal by all 3 legitimate dispersers, especially the badger, enhanced post-dispersal P. bourgaeana seed survival, supporting the “escape” predation hypothesis. Pyrus bourgaeana showed relatively high frequencies of visits by a myriad of frugivores; however, it relied on the dispersal service provided by an infrequent carnivore, the badger, rather than on those provided by the abundant mammalian herbivores. Therefore, under some circumstances, uncommon animal counterparts play major roles in their mutualistic interactions with flowering plants. Nomenclature: Váldes et al., 2007.

Barriers or corridors? The overlooked role of unpaved roads in endozoochorous seed dispersal

Summary Ubiquitous linear developments, such as dirt tracks and firebreaks, termed ‘soft’ linear developments (SLD), represent weaker landscape modifications than paved roads and highways but still could strongly affect populations and communities. Many animals avoid SLD, but some terrestrial mammals seem to select them for faecal marking. Faeces often contain many viable seeds; therefore, SLD may receive a substantial amount and diversity of seeds, which could have important overlooked consequences for plant recruitment. To evaluate the potential role of SLD as seed attractors, we surveyed transects along SLD verges and along the adjacent scrubland in three patches of Mediterranean scrubland. On each transect, we collected ungulate, carnivore and rabbit faeces during two fruiting seasons (2009 and 2010). We quantified all seeds from fleshy-fruit shrubs within faeces and compared their abundance and diversity at SLD verges vs. adjacent scrubland. The frequency of defecation along SLD varied greatly among dispersers, but ungulates avoided SLD for defecation, and carnivores and rabbits positively selected them. Seed prevalence was higher in faeces of carnivores, and seed damage low compared with faeces of rabbits and especially ungulates. The role of SLD as seed attractors was species-dependent. We found from 2·7 to 124 times more viable seeds of carnivore- and rabbit-dispersed plants along SLD than in the scrubland, while ungulate-dispersed plants were more abundant in the scrubland. Of 13 mammal-dispersed shrubs, 4 species were exclusively found along SLD verges, two were found only in the scrubland, and seven were found in both habitats. Synthesis and applications. By promoting mammal-mediated seed dispersal, soft linear developments (SLD) may act as seed corridors. Given the extremely high density of SLD world-wide, SLD hold a significant overlooked role for management and plant conservation actions. Dispersers selecting SLD can promote roadside restoration, potentially saving financial resources. These feasible benefits must be weighed up against potential spread of alien or undesirable plant species, but we demonstrate the SLD represent a valuable management tool.

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.

Responses of a top and a meso predator and their prey to moon phases

We compared movement patterns and rhythms of activity of a top predator, the Iberian lynx Lynx pardinus, a mesopredator, the red fox Vulpes vulpes, and their shared principal prey, the rabbit Oryctolagus cuniculus, in relation to moon phases. Because the three species are mostly nocturnal and crepuscular, we hypothesized that the shared prey would reduce its activity at most risky moon phases (i.e. during the brightest nights), but that fox, an intraguild prey of lynx, would avoid lynx activity peaks at the same time. Rabbits generally moved further from their core areas on darkest nights (i.e. new moon), using direct movements which minimize predation risk. Though rabbits responded to the increased predation risk by reducing their activity during the full moon, this response may require several days, and the moon effect we observed on the rabbits had, therefore, a temporal gap. Lynx activity patterns may be at least partially mirroring rabbit activity: around new moons, when rabbits moved furthest and were more active, lynxes reduced their travelling distances and their movements were concentrated in the core areas of their home ranges, which generally correspond to areas of high density of rabbits. Red foxes were more active during the darkest nights, when both the conditions for rabbit hunting were the best and lynxes moved less. On the one hand, foxes increased their activity when rabbits were further from their core areas and moved with more discrete displacements; on the other hand, fox activity in relation to the moon seemed to reduce dangerous encounters with its intraguild predator.

Local and landscape habitat determinants of water vole distribution in a patchy Mediterranean environment

Abstract We studied the distribution of a water-dependent species (southern water vole, Arvicola sapidus) in a Mediterranean region (Doñana National Park, southwest Spain) characterized by a complex array of different-sized ponds (where voles were confined) embedded in a mostly unsuitable landscape. For each surveyed pond (n = 185), a total of 26 variables related to both local (20) and landscape (6) attributes were quantified, and the presence of voles was evaluated by finding their typical signs (latrines). We found signs of water voles in 60% of ponds, despite the fact that most of them (84%) were totally dried out. A generalized linear model analysis showed that water voles were sensitive to both local and landscape attributes of ponds. At a landscape scale, presence of voles was more likely in ponds located outside the national park, close to other ponds holding voles, and far away from areas rich in potential predators and competitors. At a local scale, ponds with water voles were characterized by abundant grasses, banks well covered by brushes, low altitude, and low abundance of rabbits (Oryctolagus cuniculus). We also studied the use of microhabitat by voles within four specific ponds and found that they preferred plots of higher vegetation cover; thus, there was consistency in some cues used by water voles at the population/subpopulation scale (among different ponds) and at the behavioral scale (within ponds). Our study strongly supports the notion that the entire vole population is structured in distinct subpopulations, which are affected by a hierarchy of processes ranging from metapopulation dynamics and influenced by the landscape within which ponds are embedded as well as the local habitat quality.

Geographic variation in the adaptive landscape for seed size at dispersal in the myrmecochorous Helleborus foetidus

Literature on seed dispersal mutualisms suggests that plant populations should hardly adapt to their current dispersers. We address the predictions that selection pressures exerted by ants on dispersal-related diaspore traits of the ant-dispersed Helleborus foetidus are highly variable in space, and that geographic (inter-population) variation in these traits is unrelated to selection by current dispersers. To test these predictions we use the concept of the quantitative adaptive landscape for seed size at dispersal. Such landscape depicts the relationship between the population’s mean trait value (mean seed size in the present study) and the population’s mean fitness (mean dispersal probability in the present study). Adaptive landscapes make it possible to assess whether the mean population’s phenotype agrees with one favored by selection. We first analyse, in 12 populations of H. foetidus from southern Spain, the extent of divergence among populations in seed and elaiosome size, and the abundance, composition, and behavior of the ant communities. Seeds from a fixed set of five of these populations were offered to ants in all the study sites to fit the adaptive landscape for seed size. In addition, seeds from the local population were also offered in each site. Our results show that seed size has undergone a larger divergence among populations than elaiosome size. Despite geographic variation in ant assemblages, the adaptive landscapes for seed size at dispersal were remarkably similar among sites: ants create disruptive selection on seed size in 10 out of 12 study sites. As predicted, the basic features of these adaptive landscapes (curvature and location of the minimum) varied geographically in accordance with variation in the size of seed dispersers. Also as predicted, in most populations, the observed mean seed size does not agree with that expected from the adaptive landscapes at dispersal. However, the relevance of dispersers for seed size evolution should not be neglected since the agreement between observed and optimum seed size was stronger where dispersers were more abundant. Thus, against the general view, our results evidence that, in H. foetidus, the observed geographic variation in dispersal-related plant traits is partly linked to selection exerted by current dispersers. Geographic variation in ant assemblages determines both the existence of a selection mosaic and the degree of adjustment of populations to the patterns of selection in the mosaic.

DO FRUGIVOROUS MICE CHOOSE WHERE OR WHAT TO FEED ON

Abstract Exhaustive analyses of plant–frugivore systems have revealed that few, if any, of these plant–animal interactions are tightly coevolved. Such lack of coevolutionary evidence could be related to frugivores selecting plants based on environmental cues, rather than on plant phenotypic traits. To evaluate this hypothesis, I examined whether the pattern and extent of fruit predation by long-tailed field mice (Apodemus sylvaticus) on the perennial herb Helleborus foetidus was directly related to mouse abundance, to environmental cues, to plant phenotypic traits, or to a combination of these. Thus, I estimated mouse relative abundance (through livetrapping) and percentages of fruit predation by mice, and quantified plant environmental and phenotypic traits in 9 populations of H. foetidus in southeastern Spain during 2 years (overall, 254 plants). I found substantial variation among populations in mouse trapping success (ranging from 0.0 to 21.8 individuals/100 trap nights), size of fruit crops (8.6–28.9 fruits per plant), and percentages of fruit predation by mice (0.0–93.3%). However, no simple relationship was found between mouse abundance (as estimated by trapping success) and strength of fruit predation. None of the 4 measured plant phenotypic traits (e.g., number of fruits or plant size) had a significant effect on mouse foraging. Conversely, 2 of the 6 environmental traits considered (substrate and distance to nearest tree) influenced fruit predation by mice. Plants located on rocky substrates and nearby trees experienced higher percentages of predation and this result was rather consistent across the 2 years and the 2 levels considered (inter- and intrapopulation). Even though mice could have selected other plant phenotypic traits not accounted for (e.g., chemical traits), such hypothetical phenotypic selection appears to be inconsequential as a source of individual variation in H. foetidus maternal fitness because its effects could have been “diluted” by the overwhelming influence of environmental factors. Thus, the results support the initial hypothesis that the net outcomes of the interaction between H. foetidus and mice in southeastern Spain may not have strong coevolutionary consequences.

Indirect effects of alternative food resources in an ant–plant interaction

The seeds of many plant species present a food body that is consumed by animal dispersers. In theory, if the animals are polyphagous, the availability of alternative food resource other than the diaspore itself may influence its dispersal and survival. We used the myrmecochore Helleborus foetidus L. (Ranunculaceae), the seeds of which are attached to a lipid-rich elaiosome that is attractive to ants, as a model system to investigate (1) whether alternative foods that are present along with the plant affect ant foraging behavior and diaspore removal and (2) whether food availability in an ant nest affects seed predation and germination. In a field experiment, artificial diaspore depots were offered together with either sugar, insect corpses, seed, or no food (control). Contrary to the prediction that ants would rather concentrate their foraging effort on the highly rewarding alternative foods only, many workers, attracted by the sugar, switched to the hellebore diaspores, which significantly enhanced removal rate. Results obtained in the laboratory further indicated that the larvae of Aphaenogaster iberica (a major seed disperser) predated more on the H. foetidus embryos when no alternative food was available. This, in turn, slightly reduced seed germination. Overall, these results shed light, for the first time, on the potential indirect effects of alternative resources on the fate of diaspores adapted for ant dispersal.