Computer-generated null models as an approach to detect perceptual range in mark–re-sight studies – an example with grasshoppers

Abstract.  1. Dispersal and habitat detection are key factors for the colonisation of habitat fragments in heterogeneous landscapes. The ability to recognise a habitat from a certain distance should increase the survival chances of a dispersing individual; however, due to methodological problems there is little information on the perceptual range of most species.
2. In a field experiment, 44 individually marked grasshoppers of the species Oedipoda caerulescens (Orthoptera: Acrididae: Locustinae) were released into an unfamiliar, hostile environment at various distances from a patch of preferred habitat.
3. Whether individuals reached the habitat or not was measured, as well as the daily movement distances. The number of individuals that reached the habitat was tested against computer-generated predictions based on different underlying rules for the movement behaviour of individuals but not accounting for the ability to detect habitat from distance.
4. On the first day a significantly higher proportion of grasshoppers arrived in the habitat than predicted by any of the null models.
5. It was concluded that individuals of O. caerulescens are able to detect their preferred habitat from a distance.
6. Edge permeability was very low as none of the individuals left the habitat once they had reached it.
7. Additional analyses showed that individuals changed movement behaviour from a directed walk with great daily distances in unsuitable habitat to a walk with significantly shorter daily distances within the preferred habitat.
8. The problems that arose in the field experiment are discussed and recommendations are given for further studies.     

Evaluating the role of environmental familiarity and behaviour in the success of wildlife translocation: A grizzly bear case study using agent-based modelling

Human-carnivore systems are built on multi-scalar complex processes often resulting in conflicts that force wildlife managers to address what are conceived as problem individuals. In North America, the grizzly bear (Ursus arctos) is often involved in human-bear conflict with management measures such as translocations, in which problem individuals are moved to new areas, being used to reduce conflict risk. While translocations offer a non-lethal alternative to managing conflict animals, they show varying levels of success. Our objective was to perform a novel assessment of grizzly bear translocation success through agent-based simulation by evaluating how familiarity with landscape features coupled with behavioral traits affects the way individuals use resources in a new environment. Our results showed that bears translocated to familiar habitat used high-quality habitat more than bears moved to areas with unfamiliar landscape characteristics. Increased exploration led to greater use of high-quality habitat in the long run but resulted in reduced use of high-quality habitat during the first two years following a translocation. Habitat quality use depended on scale, with bears translocated to less familiar environments accessing higher quality areas at a finer scale than bears translocated to familiar habitats. We emphasize the need to account for wildlife behavioral traits and habitat characteristics at multiple scales when selecting suitable translocation locations. Understanding the role of factors such as these on translocation outcome will help ensure the success of translocations not only as a method for managing problem wildlife, but also for population restoration, species reestablishment, and conservation translocations across the globe.     

The impact of transportation and translocation on dispersal behaviour in the invasive cane toad

Biological invasions transport organisms to novel environments; but how does the translocation process influence movement patterns of the invader? Plausibly, the stress of encountering a novel environment, or of the transport process, might induce rapid dispersal from the release site—potentially enhancing (or reducing) invader success and spread. We investigated the effect of transportation and release to novel environments on dispersal-relevant traits of one of the world’s most notorious invaders, the cane toad (Rhinella marina). We collected toads in northern New South Wales from heath and woodland habitats, manipulated the level of transport stress and either returned toads to their exact collection point (residents) or reciprocally translocated them to a novel site. Both translocation and the level of transport stress drastically altered toad dispersal rates for at least 5 days post-release. Translocated toads (depending on their level of transport stress and release habitat) moved on average two to five times further per day (mean range 67–148 m) than did residents (mean range 22–34 m). Translocated toads also moved on more days, and moved further from their release point than did resident toads, but did not move in straighter lines. A higher level of transport stress (simulating long-distance translocation) had no significant effect on movements of resident toads but amplified the dispersal of translocated toads only when released into woodland habitat. These behavioural shifts induced by translocation and transportation may affect an invader’s ability to colonise novel sites, and need to be incorporated into plans for invader control.     

Effect of immersion at low tide on distribution and movement of the mud snail, Ilyanassa obsoleta (Say), in the upper Bay of Fundy, eastern Canada

Habitat heterogeneity often affects movement behaviours of animals, and consequently their spatial distribution. We evaluated the effect of immersion at low tide on the distribution, fine-scale movement patterns and daily movement patterns of the mud snail Ilyanassa obsoleta on a mudflat in the upper Bay of Fundy, Canada. Mud snails migrate onto intertidal mudflats in the summer, and our field survey showed that their density was higher inside tide pools relative to adjacent areas that are exposed at low tide. Using time-lapse videography, we evaluated the effect of snail size, snail density, and immersion at low tide on fine-scale movement patterns of I. obsoleta. Time until snails stopped moving and burrowed was unaffected by snail size, but snails at low and high densities burrowed somewhat faster than those at intermediate densities. Snail size and snail density had no detectable effect on displacement speed or linearity of displacement. Immersion affected snail movement: snails within tide pools delayed burrowing and traveled in more convoluted paths compared to those on exposed mud. Snails increased their turning angles within tide pools, which is probably the mechanism by which aggregations are formed. We also performed a mark-recapture experiment to compare daily movement patterns of snails released inside and outside tide pools. Snails released in tide pools moved shorter distances, but did not orient themselves differently than snails released outside tide pools. Both groups exhibited significant directionality, moving against the mean water current direction over 24 h. In sum, immersion at low tide affected the behaviour and spatial distribution of snails, resulting in snail aggregations within tide pools. These snail aggregations, in turn, may be a major factor influencing spatial dynamics on mudflats, including causing changes in distribution patterns of the burrowing amphipod Corophium volutator, a dominant inhabitant and key species in the food web of mudflats.     

Interseasonal movements of greater sage-grouse,migratory behavior,and an assessment of the core regions concept in Wyoming

Animals can require different habitat types throughout their annual cycles. When considering habitat prioritization, we need to explicitly consider habitat requirements throughout the annual cycle, particularly for species of conservation concern. Understanding annual habitat requirements begins with quantifying how far individuals move across landscapes between key life stages to access required habitats. We quantified individual interseasonal movements for greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse) using radio-telemetry spanning the majority of the species distribution in Wyoming. Sage-grouse are currently a candidate for listing under the United States Endangered Species Act and Wyoming is predicted to remain a stronghold for the species. Sage-grouse use distinct seasonal habitats throughout their annual cycle for breeding, brood rearing, and wintering. Average movement distances in Wyoming from nest sites to summer-late brood-rearing locations were 8.1 km (SE = 0.3 km; n = 828 individuals) and the average subsequent distances moved from summer sites to winter locations were 17.3 km (SE = 0.5 km; n = 607 individuals). Average nest-to-winter movements were 14.4 km (SE = 0.6 km; n = 434 individuals). We documented remarkable variation in the extent of movement distances both within and among sites across Wyoming, with some individuals remaining year-round in the same vicinity and others moving over 50 km between life stages. Our results suggest defining any of our populations as migratory or non-migratory is innappropriate as individual strategies vary widely. We compared movement distances of birds marked using Global Positioning System (GPS) and very high frequency (VHF) radio marking techniques and found no evidence that the heavier GPS radios limited movement. Furthermore, we examined the capacity of the sage-grouse core regions concept to capture seasonal locations. As expected, we found the core regions approach, which was developed based on lek data, was generally better at capturing the nesting locations than summer or winter locations. However, across Wyoming the sage-grouse breeding core regions still contained a relatively high percentage of summer and winter locations and seem to be a reasonable surrogate for non-breeding habitat when no other information exists. We suggest that conservation efforts for greater sage-grouse implicitly incorporate seasonal habitat needs because of high variation in the amount of overlap among breeding core regions and non-breeding habitat. © 2012 The Wildlife Society.     

Movement Behaviour of the Carabid Beetle Pterostichus melanarius in Crops and at a Habitat Interface Explains Patterns of Population Redistribution in the Field

Animals may respond to habitat quality and habitat edges and these responses may affect their distribution between habitats. We studied the movement behaviour of a ground-dwelling generalist predator, the carabid beetle Pterostichus melanarius (Illiger). We performed a mark-recapture experiment in two adjacent habitats; a large plot with oilseed radish (Raphanus sativus) and a plot with rye (Secale cereale). We used model selection to identify a minimal model representing the mark-recapture data, and determine whether habitat-specific motility and boundary behaviour affected population redistribution. We determined movement characteristics of P. melanarius in laboratory arenas with the same plant species using video recording. Both the field and arena results showed preference behaviour of P. melanarius at the habitat interface. In the field, significantly more beetles moved from rye to oilseed radish than from radish to rye. In the arena, habitat entry was more frequent into oilseed radish than into rye. In the field, movement was best described by a Fokker-Planck diffusion model that contained preference behaviour at the interface and did not account for habitat specific motility. Likewise, motility calculated from movement data using the Patlak model was not different between habitats in the arena studies. Motility (m² d⁻¹) calculated from behavioural data resulted in estimates that were similar to those determined in the field. Thus individual behaviour explained population redistribution in the field qualitatively as well as quantitatively. The findings provide a basis for evaluating movement within and across habitats in complex agricultural landscapes with multiple habitats and habitat interfaces.     

Movements and flight morphology in the endangered Large Blue butterflies

Movements and flight morphology of the endangered Large Blue butterflies Phengaris teleius and P. nausithous in southern Poland were studied with mark-release-recapture surveys and GIS analyses. Most individuals moved relatively small distances (<40 metres) within their habitat patches. Distances covered by both species were positively related to season progression and wing length, and negatively related to body mass. P. teleius movement distances slightly exceeded those of P. nausithous. In addition, females moved longer distances than males, although the difference was significant only in P. teleius. Morphological traits appeared to be good indicators of the inter-specific and inter-sexual differences in mobility. While P. teleius individuals were heavier than P. nausithous ones, they had considerably longer wings, which may explain longer movements in the former species. Similarly, females were heavier than males in both species, but they invested more in wing size, which is likely to compensate for the negative impact of body mass on movement distances. Our results indicate that combination of GIS analysis of movement distances recorded with mark-release-recapture methods and morphometric measurements taken in field during non-lethal handling of captured individuals proved useful for studying the mobility potential of the endangered insect species.     

Movement patterns of adult Sakhalin taimen,Parahucho perryi,between stream habitats of the Bekanbeushi River system,eastern Hokkaido,Japan

The behavior of endangered adult Sakhalin taimen Parahucho perryi was tracked during 2008–2010 using acoustic telemetry in the Bekanbeushi River system, which flows through eastern Hokkaido, Japan. Movement distances per unit time of tracked P. perryi were compared between mid- and downstream habitats. Results indicated that movement distances were significantly longer in downstream habitats during all seasons. The movement distances in each stream decreased from spring to autumn. Moreover, tracked P. perryi exhibited crepuscular movement patterns; however, patterns were less pronounced in downstream habitats than in up- and midstream habitats. These findings strongly suggested that adult P. perryi exhibit nearly distinctive movement patterns across stream habitats; thus, fish may adopt different foraging tactics in each stream habitat. Fish moved more frequently in spring, which included the post-wintering and post-spawning season, most likely to search for food and more desirable habitat for recovery.     

Movements of intertidal gastropods

Movements of marked individuals of Nerita atramentosa Reeve, Austrocochlea constricta (Lamarck), Bembicium nanum (Lamarck), and Cellana tramoserica (Sowerby) were recorded at various sites in New South Wales in 1974 and 1975. A model of random movements during feeding at high tide was proposed, i.e., that animals wandered in random directions and the distances moved were exponentially distributed. Appropriate statistical tests for departures from such a model are given. The types of departure tested were non-random directions, non-exponentially distributed dis- tances, different distances in different directions, and correlated distances or directions of movement between days. With two exceptions, the movements of the animals over short periods were adequa- tely described by the assumption of random movements. One exception was A. constricta in one locality where movements of the sample were limited by it being in a large rock-pool and the other was the limpet C. tramoserica which displayed homing behaviour, so that the population could be divided into homers and non-homers. Movements of non-homing limpets were random.The mean distance moved by N. atramentosa was not significantly different from that of A. con- stricta. The mean distances moved by these two species were greater than those of B. nanum and the non-homing C. tramoserica, which were not different from each other. Adult and one-year old N. atramentosa did not differ significantly in mean distance moved, but both moved more than juveni- les. These patterns of movement are discussed with respect to hypotheses about feeding in these species.The model of movement was used to predict the effect of different percentage cover in small pools on the movement of A. constricta, which shows a preference for this micro-habitat. Increased availability of small pools reduced the mean distance moved by this species.     

The effects of overwintering and habitat type on body condition and locomotion of the wolf spider Pardosa alacris

Overwintering in temperate regions is a prominent mortality risk for invertebrates and may affect their behaviour and body condition. Pardosa alacris is a common ground dwelling spider in central European native and plantation forests, and habitat type and prey availability may play important roles in their overwintering. The effect of overwintering on body condition and behaviour of spiders in semi natural and exotic habitats is relatively unknown. Here we assess the effects of winter on spiders from native poplar and exotic pine plantations. The locomotory behaviour of P. alacris (distance covered and speed) was assessed by tracking their movement in a white circular plastic arena. We assessed body condition, body size, and total fat content. Forest type and sex had significant effects on body length. Fat content was significantly higher in the spring than in autumn, and spiders covered larger distances and were faster in autumn than in spring. Fat content had a significant negative effect on average speed. Spiders in native forests were smaller but grew more during the winter than in exotic plantations, possibly due to higher prey availability in native forests. Visually-hunting predators may significantly affect spiders. Fat spiders with better body condition moved less, and were thus less detectable by predators. However the low movement rate may result in a low rate of encountering prey items, thus lowering feeding efficiency.     

Limited perceptual range and anemotaxis in marsh rice ratsOryzomys palustris

Dispersal among suitable habitat patches could be crucial to the regional persistence of wetland species. Dispersal success of animals will depend, in part, on the distance from which they can detect suitable habitat (ie, perceptual range). We investigated the perceptual range of marsh rice rats Oryzomys palustris Harlan, 1837 during the wet season in a region of central Florida characterized by small, isolated depression marshes. O. palustris had a limited perceptual range (<10 m) indicating that individuals moving through unfamiliar habitat have restricted information from which to make movement decisions. O. palustris displayed anemotaxis during our experiment; individuals generally moved either upwind or downwind but rarely crosswind. This anemotaxis might reflect use of wind by rice rats to maintain a straight course while searching for new habitat located beyond their perceptual range.     

Home range, movement, and site fidelity of translocated northern bobwhite (Colinus virginianus) in southwest Georgia, USA

During 1997 and 1998, we compared home range, movement, and site fidelity characteristics of translocated wild northern bobwhite (Colinus virginianus) to resident birds using radiotelemetry. We captured wild bobwhites (n=74) in southwest Georgia, USA just before the breeding season and relocated them (>1.6 km from capture sites) to sites nearby where previous density estimates revealed that populations were low compared to surrounding areas. Translocated birds were equipped with radiotransmitters and released in groups of 8 to 12. Resident birds (n=166) were also captured and simultaneously monitored via radiotelemetry. We found no difference in home range size (F ₁=0.08, P=0.78), mean daily movements (F ₁=0.04, P=0.84), or distance moved from trap or release sites to arithmetic centers of home ranges (F ₁=1.58, P=0.21) between translocated and resident bobwhites. These results suggest that translocating wild bobwhites over relatively short distances into suitable habitat does not negatively influence bobwhite movement and renders site fidelity as reasonable. Therefore, translocation of wild bobwhites before breeding season can result in enhanced numbers of adult breeders in a target location and potentially augments fall populations via reproductive yield.     

Habitat Selection and Post-Release Movement of Reintroduced Brown Treecreeper Individuals in Restored Temperate Woodland

It is essential to choose suitable habitat when reintroducing a species into its former range. Habitat quality may influence an individual’s dispersal decisions and also ultimately where they choose to settle. We examined whether variation in habitat quality (quantified by the level of ground vegetation cover and the installation of nest boxes) influenced the movement, habitat choice and survival of a reintroduced bird species. We experimentally reintroduced seven social groups (43 individuals) of the brown treecreeper (Climacteris picumnus) into two nature reserves in south-eastern Australia. We radio-tracked 18 brown treecreepers from release in November 2009 until February 2010. We observed extensive movements by individuals irrespective of the release environment or an individual’s gender. This indicated that individuals were capable of dispersing and actively selecting optimum habitat. This may alleviate pressure on wildlife planners to accurately select the most optimum release sites, so long as the species’ requirements are met. There was significant variation in movement between social groups, suggesting that social factors may be a more important influence on movement than habitat characteristics. We found a significant effect of ground vegetation cover on the likelihood of settlement by social groups, with high rates of settlement and survival in dry forests, rather than woodland (where the species typically resides), which has implications for the success of woodland restoration. However, overall the effects of variation in habitat quality were not as strong as we had expected, and resulted in some unpredicted effects such as low survival and settlement in woodland areas with medium levels of ground vegetation cover. The extensive movement by individuals and unforeseen effects of habitat characteristics make it difficult to predict the outcome of reintroductions, the movement behaviour and habitat selection of reintroduced individuals, particularly when based on current knowledge of a species’ ecology.     

Local weather and body condition influence habitat use and movements on land of molting female southern elephant seals (Mirounga leonina)

Southern elephant seals (Mirounga leonina) are known to move and aggregate while molting, but little is known about their behavior on land during this time. In this study, 60 adult females were monitored (23 with GPS tags) during four molting seasons, between 2012 and 2016 at Kerguelen Archipelago, Indian Ocean. Population surveys were recorded each year (N = 230 daily counts), and habitat use was analyzed in relation to the stage of the molt and local weather. Based on stage of molt, habitat use, and movements on land, we classified the molt of elephant seals into three phases: (1) a “search phase” at the initial stage of molt when grass and wallow habitats were used and characterized by greater mean distances travelled on land per day compared with the two other phases; (2) a “resident phase”: during initial and mid‐stage of molt when animals were found in grass and wallow habitats but with less distance moved on land; and (3) a “termination phase” at the final stage of molt where grass and beach habitats were occupied with no change in distances. Windchill and solar radiation influenced individual distances moved per day (mean 590 ± 237.0 m) at the mid‐ and final stage of molt such that animals travelled greater distances on days of low windchill or high solar radiation. Individual variation in distance moved and relative habitat use were also linked to body mass index (BMI) at arrival on the colony, as females with higher BMI moved less and preferred beach habitat. Moreover, the individual rate of molt increased with the use of wallows. Aggregation rate tended to be negatively correlated with distances moved. We therefore suggest that individuals face an energetic trade‐off while molting, balancing energy expenditure between movement and thermoregulation.     

A cold-adapted reptile becomes a more effective thermoregulator in a thermally challenging environment

Thermoregulation is of great importance for the survival and fitness of ectotherms as physiological functions are optimized within a narrow range of body temperature (T _b). The precision with which reptiles thermoregulate has been proposed to be related to the thermal quality of their environments. Although a number of studies have looked at the effect of thermal constraints imposed by diel, seasonal and altitudinal variation on thermoregulatory strategies, few have addressed this question in a laboratory setting. We conducted a laboratory experiment to test whether tuatara, Sphenodon punctatus (order Rhynchocephalia), a cold-adapted reptile endemic to New Zealand, modify their thermoregulatory behaviour in response to different thermal environments. We provided tuatara with three thermal treatments: high-quality habitat [preferred T _b (T _sel) could be reached for 8 h/day], medium-quality habitat (T _sel available for 5 h/day) and low-quality habitat (T _sel available for 3 h/day). All groups maintained body mass, but tuatara in the low-quality habitat thermoregulated more accurately and tended to maintain higher T _bs than tuatara in the high-quality habitat. This study thus provides experimental evidence that reptiles are capable of adjusting their thermoregulatory behaviour in response to different thermal constraints. This result also has implications for the conservation of tuatara. A proposed translocation from their current habitat to a higher latitudinal range within New Zealand (similar to the shift from our 8 h/day to our 5 h/day regime) is unlikely to induce thermoconformity; rather, tuatara will probably engage in more effective thermoregulatory behaviour.     

Use of space by Necromys lasiurus (Rodentia,Sigmodontinae) in a grassland among Atlantic Forest fragments

The spatial patterns presented by the rodent Necromys lasiurus were studied through capture-mark-recapture in a grassland among Atlantic Coastal Forest fragments in Southeastern Brazil. Males moved farther than females. Males moved similar distances in the dry and wet seasons, whereas females moved significantly longer distances in the dry season. Home ranges sizes were estimated for 32 individuals, and varied from 0.02 to 0.52 ha. Males had larger home ranges than females when all data are pooled and in the wet season; in the dry season home ranges of both sexes were of similar sizes. Home range sizes did not vary significantly between seasons for either sex. Home ranges of males overlapped extensively among themselves and with females, whereas females showed mutually exclusive home ranges. The spatial patterns described here are consistent with the results found for this species in different habitats and they suggest that N. lasiurus has a promiscuous mating system.     

Behavior and Movement of Wild Turkey Broods

Behavioral and movement ecology of broods are among the most poorly understood aspects of wild turkey (Meleagris gallopavo) reproductive ecology. Recent declines in wild turkey productivity throughout the southeastern United States necessitate comprehensive evaluations of brood ecology across multiple spatial scales. We captured and marked 408 female wild turkeys with global positioning system (GPS)-transmitters across 9 pine (Pinus spp.)-dominated study sites in the southeastern United States during 2014–2019. We evaluated various aspects of the behavioral and movement ecology of 94 brood-rearing females until brood failure or 28 days after hatch (i.e., when poults are classified as juveniles). We found that 34 (36.2%) females had broods (≥1 poult) survive to 28 days after hatch. Broods moved >500 m away from nest sites the day after hatching, and then moved progressively farther away from nest sites over time. Daily movements increased markedly the first 3 days after hatching, and broods moved >1,000 m/day on average thereafter. Females roosted broods an average of 202 m away from nest sites the first night after hatching, but distances between consecutive ground or tree roosts were variable thereafter. Daily core areas increased from 0.8 ha the day of hatch to 4.6 ha by day 28, and range sizes increased from 6.9 ha to 27.9 ha by day 28. Broods tended to consistently select open land cover types, whereas selection for other land cover types varied temporally after hatch day. Broods spent 89% of their time foraging. Predicted daily survival for broods decreased rapidly with increasing distance moved during the initial 3 days after hatching and showed less variation during the subsequent 2 weeks post-hatch. Our findings parallel previous researchers noting that the most critical period for brood survival is the first week after hatch day. Previous researchers have attempted to identify vegetative communities used by broods under the assumption that these communities are a primary factor influencing brood success; however, our results suggest that brood survival is influenced by behavioral decisions related to movements during early brooding periods. © 2020 The Wildlife Society.     

Hygrochastic capsule dehiscence supports safe site strategies in New Zealand alpine Veronica (Plantaginaceae)

Background and Aims

Hygrochasy is a capsule-opening mechanism predominantly associated with plants in arid habitats, where it facilitates spatially and temporally restricted dispersal. Recently, hygrochastic capsules were described in detail for the first time in alpine Veronica in New Zealand. The aim of the present study was to investigate whether hygrochastic capsules are an adaptation of alpine Veronica to achieve directed dispersal to safe sites. We expect that by limiting dispersal to rainfall events, distances travelled by seeds are short and confine them to small habitat patches where both seedlings and adults have a greater chance of survival.

Methods

Dispersal distances of five hygrochastic Veronica were measured under laboratory and field conditions and the seed shadow was analysed. Habitat patch size of hygrochastic Veronica and related non-hygrochastic species were estimated and compared.

Key Results

Dispersal distances achieved by dispersal with raindrops did not exceed 1 m but weather conditions could influence the even distribution of seeds around the parent plant. Compared with related Veronica species, hygrochastic Veronica mostly grow in small, restricted habitat patches surrounded by distinctly different habitats. These habitat patches provide safe sites for seeds due to their microtopography and occurrence of adult cushion plants. Non-hygrochastic Veronica can be predominantly found in large habitats without clearly defined borders and can be spread over long distances along rivers.

Conclusions

The results suggest that hygrochasy is a very effective mechanism of restricting seed dispersal to rainfall events and ensuring short-distance dispersal within a small habitat patch. It appears that it is an adaptation for directed dispersal to safe sites that only exist within the parent habitat.     

Dispersal characteristics of seven odonate species in an agricultural landscape

Dispersal is an ecological phenomenon which is of fundamental importance to population biology. While dispersal behaviour of many orders of winged insects has received a great deal of attention, the dispersal characteristics of odonates have been poorly documented. We used capture-mark-recapture techniques to study dispersal behaviour of seven species of odonates breeding on a network of 11 small ponds in Cheshire, U.K. The ponds ranged in size from 615 to 1300 m²- and varied from 30 to 860 m apart. We found surprisingly high rates of dispersal between ponds, with 10–47% per species of recaptured individuals moving from their natal pond. The mean probability of dispersal differed significantly among species but the relationship between the probability of dispersal and distance moved consistently followed a simple negative exponential curve for all species. Most individuals stayed at their natal pond, but a few moved long distances. Neither the age at which an individual was marked (teneral vs sexually mature) nor its sex significantly affected its tendency to disperse. The negative exponential relationship suggests that dispersal should be relatively easy to incorporate in more complex models of odonate spatio-temporal dynamics. To our knowledge, this is the first large-scale, multi-species study to assess dispersal behaviour of odonates by direct observation.     

Diel variation in movement patterns and habitat use by the Iberian endemic Cabrera vole: Implications for conservation and monitoring

Understanding variations in animal movement and habitat selection behaviour over fine spatial and temporal scales remains a particularly challenging goal in ecology and conservation. Here we document for the first time the diel variations in movement patterns and habitat use by wild-ranging Cabrera voles in fragmented Mediterranean farmland, based on radiotracking data (2006–2008) of 25 adult individuals occupying stable home-ranges in vegetation mosaics dominated by wet grasses and shrubs. Results indicated that the proportion of time animals spent moving, the distance moved, and the selection strength of main vegetation types were closely linked behavioural traits, which varied considerably across different periods of the 24-h cycle. In general, voles moved more frequently and over larger distances during daytime (between 06 h15–22 h00), which was when wet grasses were also used more intensively. These patterns were generally consistent across seasons, though during the dry season there was some tendency for a decrease in movement activity during the hottest hours of the day (between 10 h15–14 h00), with peaks around crepuscular hours (06 h15–10 h00 and 18 h15–22 h00). Overall, our study provides evidence that Cabrera voles may show notable shifts in habitat use and movement patterns on a finer scale than previously considered. This supports the idea that knowledge of the diel variations in species movement-habitat relationships should strongly contribute to improving local habitat management, as well as effective sampling and monitoring programs targeting the species.