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The distribution of ticks in the Ixodes ricinus species complex is partly driven by climate, with temperature and relative humidity affecting survival. These variables are driven by macroclimate, but vary locally due to microclimate buffering. This buffering has been suggested to be one of the driving forces behind variation in tick survival and density in time and space. In order to understand the role of the herb layer with respect to this variation, we deployed I. ricinus within an existing experimental setup studying the response of forest under -storey to micrometeorological changes. This allowed for the analysis of both direct effects of warming on tick survival in controlled field conditions, as well as indirect effects through changes in herb layer biomass. Herb layer biomass estimates were observed to be higher in plots that had been experimentally warmed, with a trend towards higher survival in these warmed plots. This marginal increase in survival rate may be due to increased microclimate buffering. Comparing our results to literature implies that canopy and shrub layer vegetation have a larger effect on climate buffering, and therefore also on tick survival. Since the herb layer biomass is expected to increase due to global warming and increased frequency of disturbance-induced canopy gaps, survival in forested habitats may increase in the future. This would increase the difference in survival compared to that in open habitats.

Humans fundamentally affect dispersal, directly by transporting individuals and indirectly by altering landscapes and natural vectors. This human-mediated dispersal (HMD) modifies long-distance dispersal, changes dispersal paths, and overall benefits certain species or genotypes while disadvantaging others. HMD is leading to radical changes in the structure and functioning of spatial networks, which are likely to intensify as human activities increase in scope and extent. Here, we provide an overview to guide research into HMD and the resulting rewiring of spatial networks, making predictions about the ecological and evolutionary consequences and how these vary according to spatial scale and the traits of species. Future research should consider HMD holistically, assessing the range of direct and indirect processes to understand the complex impacts on eco-evolutionary dynamics.

An increasing number of studies have investigated the consequences of biodiversity loss for the occurrence of vector-borne diseases such as Lyme borreliosis, the most common tick-borne disease in the northern hemisphere. As host species differ in their ability to transmit the Lyme borreliosis bacteria Borrelia burgdorferi s.l. to ticks, increased host diversity can decrease disease prevalence by increasing the proportion of dilution hosts, host species that transmit pathogens less efficiently. Previous research shows that Lyme borreliosis risk differs between forest types and suggests that a higher diversity of host species might dilute the contribution of small rodents to infect ticks with B. afzelii, a common Borrelia genospecies. However, empirical evidence for a dilution effect in Europe is largely lacking. We tested the dilution effect hypothesis in 19 Belgian forest stands of different forest types along a diversity gradient. We used empirical data and a Bayesian belief network to investigate the impact of the proportion of dilution hosts on the density of ticks infected with B. afzelii, and identified the key drivers determining the density of infected ticks, which is a measure of human infection risk. Densities of ticks and B. afzelii infection prevalence differed between forest types, but the model indicated that the density of infected ticks is hardly affected by dilution. The most important variables explaining variability in disease risk were related to the density of ticks. Combining empirical data with a model-based approach supported decision making to reduce tick-borne disease risk. We found a low probability of a dilution effect for Lyme borreliosis in a north-western European context. We emphasize that under these circumstances, Lyme borreliosis prevention should rather aim at reducing tick-human contact rate instead of attempting to increase the proportion of dilution hosts.

Urbanisation represents one of the most radical forms of terrestrial land use change and has been shown to lead to alterations in ecosystem functioning and community dynamics and changes in individual phenotypic traits. While the recent surge in microbiome studies has brought about a paradigm shift by which individuals cannot truly be considered independently of the bacterial communities they host, the role of gut microbiota in organismal response to human-induced environmental change is still scarcely studied. Here, we applied a metabarcoding approach to examine the impact of urbanisation on the gut microbiota of Passer domesticus. We found urbanisation to be associated to lower microbiota species diversity, modifications in taxonomic composition and community structure, and changes in functional composition. The strength of these relationships, however, depended on the spatial scale and season at which they were considered. Such spatio-temporal effect suggests that urbanisation may dampen the natural seasonal variation of the gut microbiota observed in more pristine habitats, potentially influencing the fitness of urban organisms. Our results hence shed light on a hitherto little considered perspective, i.e. that the negative effects of urbanisation on city-dwelling organisms may extend to their microbiomes, causing potential dysbioses.

The risk of tick-borne disease in humans depends on the exposure to pathogen-infected ticks, which in turn is driven by local tick population densities, pathogen prevalence and human activity. Variation in tick densities and pathogen prevalence between green spaces differing in habitat characteristics, location and geography has been well documented. In contrast, variation within green spaces, although vital for management and prevention of disease risk, remains poorly understood. Studying this variation may lead to a better understanding of the drivers of small-scale tick distribution and reveal priority locations for tick management. We sampled ticks within green spaces at three location types representing different green space infrastructures and levels of human activity: (1) a structural element (e.g. bench); (2) the ecotone 40 m further along the adjacent trail and; (3) the interior of the associated forest stand, 20 m perpendicular to the trail, between (1) and (2). Drag sampling took place in 2018 and 2019 at 36 locations in 10 green spaces located in the Campine region of Flanders, Belgium. The density of questing nymphs (DON) was lowest at structural elements and slightly higher adjacent to trails. The highest tick densities were recorded in the forest interior. DON was higher in deciduous than in coniferous forests as well as in stands with a more developed shrub layer. This was true for all location types, as we observed a strong correlation of DON between location types within forest stands. This enables the prediction of DON within forest stands, thus enabling the prediction of DON near infrastructure based on the associated forest stand characteristics. Prevention and management efforts should be focused on infrastructure in or adjacent to deciduous, structure-rich forest stands, although large variation in DON at all location types indicates overall, factual risk while using green space infrastructure. This work was supported by the Research Foundation - Flanders [grant number 60897] Van Gestel, M (corresponding author), Campus Drie Eiken,Room D1-46,Univ Pl 1, B-2610 Antwerp, Belgium. Mats.vangestel@uantwerpen.be

Animal personalities can play an important role in how individuals deal with specific social situations, which may have important fitness consequences. A link between personality and social skills seems obvious from a human perspective and it is therefore surprising that relatively few studies have looked at the effect of animal personality on communicative interactions. In this study we tested the evidence for personality-related variation in birds during vocal interactions in the field. We scored individual variation in exploratory behaviour of great tits, Parus major, in repeated trials of a novel environment test in the laboratory and related this score to approach and vocal behaviour in response to playback of conspecific songs in the field. Contrary to our expectation, we found males with low exploration scores approached the speaker more closely than birds with high exploration scores. Birds with high exploration scores seemed to respond less aggressively while dealing with the simulated intruder vocally by switching song types more often. Our results suggest that slow-exploring birds in the laboratory respond more strongly during natural interactions in the field. An independent and very similar study also revealed a correlation between personality score and playback response, but with a seemingly contrasting outcome. A comparison of the two studies provides insights into the complexity of interpreting playback results and territorial response patterns in general.

Cavity shortage limits secondary cavity-nesting birds (SCN) assemblages in intensively-managed forests with few cavities, but whether cavity availability limits SCN in cavity-rich forests remains unclear. To address this issue, we used a replicated before-after-control-impact design in which the availability of cavities was experimentally reduced and increased in cavity-rich Quercus pyrenaica forests. Cavity-blocking and nest-box addition led to reduction by 66% and increase by 185%, respectively, of nest densities of blue (Cyanistes caeruleus) and great (Parus major) tits. Analysis of cavity characteristics suggests that tits occupied less suitable cavities in blocking plots compared to control and nest-box addition plots after treatments, further indicating that the availability of suitable nest-sites may limit tit populations. No effect of cavity manipulation was found for short-toed treecreepers (Certhia brachydactyla) and Eurasian nuthatches (Sitta europaea), which defend larger territories than tits and whose numbers may be more influenced by territoriality than by nest-sites. Alternatively, high plasticity in nest-site use of treecreepers may enable them to cope with reductions in cavity availability and increased interspecific competition. Spotless starlings (Sturnus unicolor) were little affected by cavity manipulation. Often foraging on pastures, starlings may be more limited through reduced foraging opportunities in this forested landscape than by nest-sites. In addition, starlings may exclude other species from their preferred cavities to cope with reductions in numbers of suitable cavities. Community responses to the variation in cavity abundance in cavity-rich Pyrenean oak forests may therefore vary considerably among species, depending on their plasticity in nest-site use, behavioral dominance, foraging conditions or social structure. Thus, management actions aimed to increase cavity abundance and suitability for SCN communities in cavity-rich forests should consider inter-specific interactions and species-specific characteristics of the targeted species.

Secondary cavity-nesting birds (SCN), which cannot create their own breeding cavities, are expected to be influenced by habitat alteration caused by forest management practices, but the mechanisms underlying the distribution pattern of SCN subjected to different management systems are poorly known. To improve our knowledge on these mechanisms, we examine cavity abundance, cavity occupation and reproductive performance of SCN in Pyrenean oak ( Quercus pyrenaica ) forests subjected to two management systems: (i) dense “young forests”, maintained at such stage by clear-cuttings and burns, and (ii) “old forest”, subjected to extensive traditional grazing and scarce firewood extraction by selective cutting. Young forests had considerably lower density of cavities (1.29 ± 0.71 vs 15.09 ± 2.00 cavities ha −1 ), SCN species (0.18 ± 0.11 vs 0.61 ± 0.07 species ha −1 ) and nests (0.40 ± 0.27 vs 2.67 ± 0.25 nests of all SCN ha −1 ) than old forests, indicating that a low availability of cavities may limit SCN assemblages in young oak forests. However, reproductive parameters of great ( Parus major ) and blue ( Cyanistes caeruleus ) tits associated with the availability of food (laying date, clutch size, nestling number and weight, adult weight) did not differ between both forest types, suggesting that food supply was not reduced in young forests, at least for tits during the breeding season. Large diameter (up to 170 cm dbh) decayed trees were the most likely to hold cavities, but birds preferred smaller living cavity-trees for nesting (90% of nests in 21–65 cm dbh trees). The preservation of cavity-trees within traditionally managed old oak forests is crucial in providing nesting opportunities to SCN. Besides, the protection of these traditionally managed forests would also benefit to other forest organisms that depend on old and open oak forests.

When habitats become fragmented, variation in patch size and quality are expected to impose changes on the spacing pattern and social organization of animal populations. General theory predicts different possible responses including shrinking home ranges (fission response), increasing range overlap (fusion) and incorporation of multiple patches in the home range (expansion response) as fragmentation increases. We studied space use and social organization in a metapopulation of red squirrels ( Sciurus vulgaris ) in 15 woodland fragments differing in size and tree species composition. Home ranges and core areas of males were larger than females, and fragmentation had different and complex effects on the spacing pattern of both sexes. In food-supplemented patches, high densities led to increased intra-sexual overlap. In linear-shaped patches, squirrels used smaller home ranges and core areas and had lower male–male and male–female overlap levels, independent of patch quality or size. Home range and core area size of males increased with patch size, and male core areas overlapped extensively those of other males and females. Hence males seemed to show a fission response only in some patches. In contrast, home range and core area size of females was not related with patch size, but decreased with habitat quality, supporting predictions of a fusion response and intra-sexual defense of food-based core areas. Hence, where patch size and shape strongly affected space use of male red squirrels, social organization of females was only affected in small, food-supplemented patches, suggesting that the basic spatio-social organization of adult females is very resistant to fragmentation.

Habitat fragmentation and habitat loss are widely recognized as major threats to biodiversity on a regional as well as on a global scale. To restrict its effects, ecological networks such as the trans-European network NATURA2000 are being developed based on the assumption that structural connections between habitat fragments lead to increased exchange through dispersal and a higher viability of (meta)populations. However, there is a great need for techniques that translate these networks and/or structural characteristics of landscapes into functional connectivity for specific organisms. Least-cost analysis has the capacities to fulfill these needs, but has never been validated against actual observations of dispersal paths. Here we present a method to validate the results of a least-cost analysis by comparing realized movement paths of hedgehogs in unfamiliar areas, obtained by radiotracking, with statistics on landscape-wide distribution of cost values. The degree of correspondence between empirical dispersal paths and the output of a least-cost analysis can be visualized and quantified, and least-cost scenarios can be statistically compared. We show that hedgehogs moved along paths with significantly lower cost values than the average landscape, implying that they took better than random routes, but performance was relatively poor. We attribute this to the relatively generalistic habitat use of the model species and the rather homogeneous landscapes. We conclude that this approach can be useful for further validation of the least-cost model and allows a direct comparison of model performance among different taxa and/or landscapes.

Assessment of habitat use for species of conservation concern can lead to important measures for habitat conservation. In high-Andean Polylepis forests (3000–5000 m), two such species are the Giant Conebill (Oreomanes fraseri) and the Tawny Tit Spinetail (Leptasthenura yanacensis), two forest specialists confronted with the loss and fragmentation of their habitat. The high degree of habitat specialization with strong confinement to Polylepis forest patches predisposes them to a much lower threshold to habitat fragmentation than more generalist species. In this study, we examined their habitat use. Through the use of principal component analysis and generalized linear models considering the vegetation structure, tree density, ground cover and interior and edge plots, we found micro-habitat use only for O. fraseri. This species was more abundant (foraging and perching) in plots with high presence of mature trees. Also, both species showed strong edge avoidance, regardless of fragment size or vegetation characteristics. Adverse microclimate conditions, such as extreme temperatures during warm or cold periods at edges may be the most probable cause of edge avoidance. The reduction of edge:interior ratio within Polylepis fragments and management measures against mature tree cutting is suggested for the conservation of these two near threatened Andean birds.

The occurrence of different conspecific female colour morphs, with one of the morphs resembling the male, is supposed to have consequences for mate choice. There are two hypotheses linking mate choice and female colour polymorphism. First, males may mate predominantly with female morphs that differ from the male because they do not recognize androchrome females as females (male mimic hypothesis). Second, males may be more attracted to the most common morph in the population (habituation hypothesis). We tested these hypotheses in five populations of the same species, Ischnura elegans, with a range of androchrome frequencies. In each population we performed binary choice experiments in small cages. Males did not consistently prefer gynochrome females but mated predominantly with the most common morph in the population. Moreover, a reanalysis of the available damselfly data in the literature also supported the habituation hypothesis. Copyright 1999 The Association for the Study of Animal Behaviour.