Quantifying fine-scale resource selection by introduced European hedgehogs (Erinaceus europaeus) in ecologically sensitive areas

Introduced predators are important drivers of ecosystem change and can threaten native species. The European hedgehog (Erinaceus europaeus) was introduced from Britain into New Zealand where it is currently widespread, including in braided-river environments of the interior cold drylands where it might threaten native species such as riparian ground-nesting birds. The establishment of hedgehogs in braided-river environments may be facilitated by adjacent pastoral landscapes that provide food, primarily invertebrates, and dry shelter. Forays by hedgehogs into native prey habitats, such as riverbed floodplains, increase predation pressure. Understanding the spatial ecology of introduced predators can improve effectiveness of control measures. We assessed spatial resource selection by hedgehogs in a braided-river environment by tracking 27 individuals for 4–8 days in summer and autumn using microGPS-backpacks. We extracted fine-scale landscape variables from a map created using very high resolution satellite imagery to model home range placement within the study area. We also assessed habitat composition and ranking within high-use areas using compositional analysis. Hedgehogs established home ranges in pastoral landscapes containing abundant edges and high vegetation productivity (mainly green pastures and shrubs), and selected pastures and patches of shrubs as high-use areas. Hedgehogs avoided riverbed floodplains, suggesting that reported predation events on ground-nesting birds might be a consequence of secondary predation or individual specialization. We recommend that predation of native species by hedgehogs might be best alleviated if trapping is focused on those areas selected by native fauna of conservation concern (e.g. riverbed floodplains), as well some biologically-determined buffer surrounding these sites.     

Design of a GPS backpack to track European hedgehogs <Emphasis Type="Italic">Erinaceus europaeus</Emphasis>

We report on the design and construction of a Global Positioning System (GPS) backpack to collect positional data of European hedgehogs Erinaceus europaeus. The device consisted of a microGPS unit plus a VHF transmitter to facilitate unit recovery. It was constructed to articulate when the animal rolled up and to prevent snagging on objects or nests. Backpacks were fitted to 28 hedgehogs with eight reattachments at different seasons (N = 36 samples). Units fixed hedgehog positions at high rate for an average of 5 days to address our study on spatial ecology at fine scale. We recorded the normal execution of defensive rolling behaviour, impediments on natural movements across vegetation and nest occupancy, and also changes in body mass. We could not discern any negative effect associated with the backpack for attachments up to 8 days; hence, we consider this design to be appropriate for tracking European hedgehogs over this length of time.     

Hawk Eyes II: Diurnal Raptors Differ in Head Movement Strategies When Scanning from Perches

Background

Relatively little is known about the degree of inter-specific variability in visual scanning strategies in species with laterally placed eyes (e.g., birds). This is relevant because many species detect prey while perching; therefore, head movement behavior may be an indicator of prey detection rate, a central parameter in foraging models. We studied head movement strategies in three diurnal raptors belonging to the Accipitridae and Falconidae families.

Methodology/Principal Findings

We used behavioral recording of individuals under field and captive conditions to calculate the rate of two types of head movements and the interval between consecutive head movements. Cooper''s Hawks had the highest rate of regular head movements, which can facilitate tracking prey items in the visually cluttered environment they inhabit (e.g., forested habitats). On the other hand, Red-tailed Hawks showed long intervals between consecutive head movements, which is consistent with prey searching in less visually obstructed environments (e.g., open habitats) and with detecting prey movement from a distance with their central foveae. Finally, American Kestrels have the highest rates of translational head movements (vertical or frontal displacements of the head keeping the bill in the same direction), which have been associated with depth perception through motion parallax. Higher translational head movement rates may be a strategy to compensate for the reduced degree of eye movement of this species.

Conclusions

Cooper''s Hawks, Red-tailed Hawks, and American Kestrels use both regular and translational head movements, but to different extents. We conclude that these diurnal raptors have species-specific strategies to gather visual information while perching. These strategies may optimize prey search and detection with different visual systems in habitat types with different degrees of visual obstruction.     

Factors affecting hedgehog presence on farmland as assessed by a questionnaire survey

The West European hedgehog, (Erinaceus europaeus, Linnaeus 1758) is widely distributed in Western Europe. However, there is evidence of decline in parts of its range. Changes in agricultural management have partly been the driving force behind the loss of species diversity and abundance, and it has been argued that these changes play a role in the decline of hedgehogs as well. We used a questionnaire to investigate the current distribution of hedgehogs on farmland throughout Great Britain with a focus on different environmental zones. Additionally, we identified environmental correlates that related to the distribution of hedgehogs with the aim to get a better understanding of what is needed to design appropriate strategies targeted at the conservation of hedgehogs. Our study illustrates that, although the impact of several variables was rather ambiguous, displaying positive effects in some environmental zones and negative effects in other, major roads and Eurasian badgers (Meles meles, Linnaeus 1758) can have large scale negative effects on hedgehogs. Farm management related factors did not show a consistent impact on hedgehog presence. Conservation strategies should therefore be aimed at lessening the impacts of major roads and badger presence. Wildlife passages, for instance, may provide hedgehogs safe passages across roads. Additionally, increasing the habitat complexity in order to reduce the impact of predators can be beneficial for prey species, such as hedgehogs, and should be considered as a conservation strategy for them.     

Factors affecting hedgehog (<Emphasis Type="Italic">Erinaceus europaeus</Emphasis>) attraction to rural villages in arable landscapes

Although residential areas are often unfavourable for wildlife, some species can take advantage of the available shelter and anthropogenic sources of food such as supplementary feeding. The European hedgehog (Erinaceus europaeus) is increasingly associated with gardens and villages and less so with arable farmland. Suggested drivers for this include the following: hedgehogs’ attraction to higher food densities, including natural prey and anthropogenic sources, a greater range of day nest sites and warmer microclimates in rural villages, coupled with decreased risk of predation by badgers (Meles meles). We investigated the contribution of these drivers by radio-tracking hedgehogs on four arable sites, two with badgers present. Seventy-eight hedgehogs were tracked, 32 yielding enough data to calculate home range sizes. At the home range and landscape scales, gardens and buildings were the highest ranked habitats compared with their availability. Woodland and arable land were the lowest ranked compared with their availability. Villages were the most selected habitat for nesting. When hedgehogs were found closer to buildings, their ranges were smaller and we speculate this is due to increased food availability in villages. Where badgers were present hedgehogs remained closer to cover and their home ranges were on average 12.2 ha smaller. On badger-occupied sites, 50% fewer radio-tracking fixes were on arable land. We conclude that resource availability coupled with nest site selection and badger presence drives hedgehogs’ selection of rural villages. We found no effect of ambient temperature on habitat use. We recommend focusing conservation efforts on maintaining hedgehog populations in rural villages.     

Intraspecific and seasonal differences in the diet of feral ferrets (

This study reports the diet of feral ferrets (Mustela furo) in a pastoral habitat, East Otago, South Island, New Zealand. Rabbits (Oryctolagus cuniculus) were the most common prey of ferrets, occurring in 86.7% of seats, but birds (12.4%) and invertebrates (11.3%) were also frequently eaten. Female ferrets ate more non-lagomorph prey items, especially invertebrates and birds than males. No significant dietary differences were found between juvenile and adult ferrets except in summer when juveniles ate more lagomorph prey. There were seasonal differences in the consumption of rabbits, invertebrates, skinks, possums (Trichosurus vulpecula) and small and large secondary prey items. Seasonal differences in ferret diet are likely to be related to the relative abundance of the various prey items. Lagomorph availability may also be a determinant of the frequency of occurrence of other prey items in the diet. Dietary differences may differentially influence the functional response of adults and juveniles and/or males and females to rabbit control or other manipulations of prey populations. Bovine tuberculosis (Mycobacterium bovis) infections in ferret populations show intraspecific variation with more males than females and more adults than juveniles infected. Intraspecific dietary differences in diet were not observed in the species (possums and hedgehogs (Erinaceus europaeus)) considered to be the main sources of infection for ferrets.     

Translocation of the Eastern Bristlebird 1: radio‐tracking of post‐release movements

Summary Translocating birds to a new area of habitat to restore or supplement depleted populations may pose a significant threat to the translocated individuals. While for many species, translocated individuals appear to move larger distances than resident animals, species with poor dispersal capacity may be restricted in movements and translocation methods may need to accommodate differences in movements to ensure success. In this study, designed to provide insights to inform our broader programme of translocations in New South Wales, Australia, we investigated post‐release movements in the endangered, semi‐flightless Eastern Bristlebird (Dasyornis brachypterus). We predicted that movements would be minimal, with few differences between males and females, similar to published information for a resident un‐manipulated population. Following the release of 45 birds at a host location at Jervis Bay, NSW, over a 3‐year programme, we followed individuals for up to 2 weeks using radio‐tracking. The translocated birds had larger maximum movements and moved through much larger home ranges than non‐translocated individuals from the resident population. Translocated birds moved 300 m further after release when conspecifics were present. Males moved further than females and tended to have larger home ranges, although average daily displacement did not differ. We concluded that the semi‐flightlessness of the species does not result in minimal movements. Release at a small number of locations in the new habitat was considered appropriate for the species, as animals seem to move enough to find new unoccupied areas in a relatively short period. This work provided us with increasing confidence to continue with further translocations.     

Scats and den contents as indicators of the diet of stoats (Mustela erminea) in the Tasman Valley,South Canterbury,New Zealand

Stoats are significant predators of native fauna in New Zealand. They occur in many habitat types and consume a wide range of prey. The diet of stoats in the Tasman River, South Canterbury, was studied by analysis of scats and den contents. Analysis of 206 scats showed that stoats ate mainly lagomorphs, birds and invertebrates. Minor components included mice, lizards, fish and hedgehogs. Stoats ate more birds in spring than in autumn, and female stoats ate more invertebrates than did males. The contents of 219 dens collected in the same area at the same time provided further information. Birds and lagomorphs occurred at high frequency in dens, and other components were minor. Remains in dens were larger than in scats and allowed identification of many more prey items to species level. Den contents revealed a potentially substantial impact of stoats on threatened shorebirds locally; this impact was not detected by analysis of scats.     

Anthropomorphism in Japanese Women's Status Terms used in Talk to Potential Guide Dogs

Abstract

We surveyed residents' attitudes toward common urban animals and their participation in animal-oriented activities in the city of Trondheim, Norway. The results show that people most like small birds, squirrels, butterflies, hedgehogs, ducks, geese and dogs, and dislike bats, snails, invertebrate species, mice and rats. Birds of prey, foxes, cats, bumblebees, magpies, pigeons, badgers, gulls, grasshoppers and crows received a neutral ranking. Generally, females more than males liked the popular and neutral species, while males more than females liked the less-preferred animals. A negative association was found between age of respondents and preferences for birds of prey, dogs, cats, badgers, bats, mice and rats. This relation was positive for some invertebrate species, and small and medium-sized birds. A positive correlation was found between educational level of the respondents and preference scores for most of the species listed. Watching television programs about nature (59% often/very often) and watching/feeding birds (41%) were the most frequently reported animal-related activities. When walking in the neighborhood, important animal-related motives for doing this were to observe birds (42%) and to observe mammals (34%). Interest in bird observation and television programs about nature increased with increasing age. Few respondents reported experiencing problems with wildlife, but dogs and cats were more often (36%) considered to create problems. These results indicate that wildlife plays an important role in shaping urban residents' daily experiences, and that both animals and their habitats should have a higher priority in urban planning and management.     

Climate and density influence annual survival and movement in a migratory songbird

Assessing the drivers of survival across the annual cycle is important for understanding when and how population limitation occurs in migratory animals. Density‐dependent population regulation can occur during breeding and nonbreeding periods, and large‐scale climate cycles can also affect survival throughout the annual cycle via their effects on local weather and vegetation productivity. Most studies of survival use mark–recapture techniques to estimate apparent survival, but true survival rates remain obscured due to unknown rates of permanent emigration. This is especially problematic when assessing annual survival of migratory birds, whose movement between breeding attempts, or breeding dispersal, can be substantial. We used a multistate approach to examine drivers of annual survival and one component of breeding dispersal (habitat‐specific movements) in a population of American redstarts (Setophaga ruticilla) over 11 years in two adjacent habitat types. Annual survival displayed a curvilinear relation to the Southern Oscillation Index, with lower survival during La Niña and El Niño conditions. Although redstart density had no impact on survival, habitat‐specific density influenced local movements between habitat types, with redstarts being less likely to disperse from their previous year's breeding habitat as density within that habitat increased. This finding was strongest in males and may be explained by conspecific attraction influencing settlement decisions. Survival was lowest in young males, but movement was highest in this group, indicating that apparent survival rates were likely biased low due to permanent emigration. Our findings demonstrate the utility of examining breeding dispersal in mark–recapture studies and complement recent work using spatially explicit models of dispersal probability to obtain greater accuracy in survival estimates.     

From sensor data to animal behaviour: an oystercatcher example

Animal-borne sensors enable researchers to remotely track animals, their physiological state and body movements. Accelerometers, for example, have been used in several studies to measure body movement, posture, and energy expenditure, although predominantly in marine animals. In many studies, behaviour is often inferred from expert interpretation of sensor data and not validated with direct observations of the animal. The aim of this study was to derive models that could be used to classify oystercatcher (Haematopus ostralegus) behaviour based on sensor data. We measured the location, speed, and tri-axial acceleration of three oystercatchers using a flexible GPS tracking system and conducted simultaneous visual observations of the behaviour of these birds in their natural environment. We then used these data to develop three supervised classification trees of behaviour and finally applied one of the models to calculate time-activity budgets. The model based on accelerometer data developed to classify three behaviours (fly, terrestrial locomotion, and no movement) was much more accurate (cross-validation error?=?0.14) than the model based on GPS-speed alone (cross-validation error?=?0.35). The most parsimonious acceleration model designed to classify eight behaviours could distinguish five: fly, forage, body care, stand, and sit (cross-validation error?=?0.28); other behaviours that were observed, such as aggression or handling of prey, could not be distinguished. Model limitations and potential improvements are discussed. The workflow design presented in this study can facilitate model development, be adapted to a wide range of species, and together with the appropriate measurements, can foster the study of behaviour and habitat use of free living animals throughout their annual routine.     

Predictors of clutch predation of a globally significant avifauna in New Zealand's braided river ecosystems

Predation by introduced mammals is decimating New Zealand's indigenous fauna. Understanding factors that influence this process allows resources for predator control to be applied with maximum effect. This study examines how predation of a secondary prey species (a relatively common but declining native plover, the banded dotterel Charadrius bicinctus ) varied with reductions in abundance of a major prey source (rabbits), kill-trapping of predators, nest density and habitat complexity. Banded dotterels mostly nest in open braided riverbeds alongside a number of endemic threatened species. We measured the fate of 753 dotterel clutches exposed to predation by cats, ferrets and hedgehogs. We found key times and places of high predation risk. Immediately after widespread reduction in rabbit populations by rabbit haemorrhagic disease (RHD), clutch predation rates were almost as high (mean, 50%) as those recorded during past rabbit poisoning programmes (mean, 57%). Both rates were significantly higher than the mean predation rate of 22% without rabbit control, suggesting a shift in predator diet immediately after rabbit population declines. Unlike after rabbit poisoning, clutch predation rate remained high in the years after RHD. Other patterns observed included higher clutch predation rate where nest density was lower, suggesting that predation can potentially cause local extinction. Clutch predation was also higher along riverbed margins where vegetation was dense. There was equivocal evidence for an effect of predator kill-trapping on clutch predation rate. Management strategies that could potentially reduce clutch predation risks include focusing predator mitigation measures during periods of rabbit decline, maintaining them for more than one breeding season if the rabbit declines are widespread (e.g. RHD epidemics), and applying greater effort at sites with relatively low nest density and along riverbed margins where predator use is more frequent.     

The nest predator community of grassland birds responds to agroecosystem habitat at multiple scales

Nest predation is the leading cause of reproductive failure for grassland birds of conservation concern. Understanding variation in nest predation rates is complicated by the diverse assemblage of species known to prey on nests. As part of a long‐term study of grassland bird ecology, we monitored populations of predators known to prey on grassland bird nests. We used information theoretic approach to examine the predator community's association with habitat at multiple scales, including local vegetation structure of grassland patches, spatial attributes of grassland patches (size and shape), and landscape composition surrounding grassland patches (land cover within 400 and 1600 m). Our results confirmed that nest predators respond to habitat at multiple scales and different predator species respond to habitat in different ways. The most informative habitat models we selected included variability in local vegetation (CV in the density of forbs), local patch (area and edge‐to‐interior ratio), and landscape within a 1600 m buffer around grasslands (percent of land covered by human structures and development). As a separate question, we asked if models that incorporated information from multiple scales simultaneously might improve the ability to explain variation in the predator community. Multi‐ scale models were not consistently superior to models derived from variables focused at a single spatial scale. Our results suggest that minimizing human development on and surrounding conservation land and the management of the vegetation structure on grassland fragments both may benefit grassland birds by decreasing the risk of nest predation.     

Vegetation maps based on remote sensing are informative predictors of habitat selection of grassland birds across a wetness gradient

Vegetation is a major environmental factor influencing habitat selection in bird species. High resolution mapping of vegetation cover is essential to model the distribution of populations and improve the management of breeding habitats. However, the task is challenging for grassland birds because microhabitat variations relevant at the territory scale cannot be measured continuously over large areas to delineate areas of higher suitability. Remote sensing may help to circumvent this problem. We addressed this issue by using SPOT 5 imagery and phytosociological data. We mapped grassland vegetation in a floodplain using two methods. We (i) mapped the continuous Ellenberg index of moisture and (ii) identified 5 vegetation classes distributed across the wetness gradient. These two methods produced consistent output maps, but they also provided complementary results. Ellenberg index is a valuable proxy for soil moisture while the class approach provided more information about vegetation structure, and possibly trophic resources. In spite of the apparent uniformity of meadows, our data show that birds do not settle randomly along the moisture and vegetation gradients. Overall birds tend to avoid the driest vegetation classes, i.e. the highest grounds. Thus, vegetation maps based on remote sensing could be valuable tools to study habitat selection and niche partition in grassland bird communities. It is also a valuable tool for conservation and habitat management.     

Factors affecting the abundance of introduced hedgehogs (Erinaceus europaeus) to the Hebridean island of South Uist in the absence of natural predators and implications for nesting birds

Introduced hedgehogs Erinaceus europaeus are a known threat to ground-nesting birds on many islands. Spring hedgehog density and sex ratio were measured over a 5-year period at four plots on the 315 km² Hebridean island of South Uist. The mean instantaneous density on the sandy-soiled machair plots (31.8 hedgehogs km⁻², se 2.95) was over twice that on the peaty-soiled blackland plots (15.4 hedgehogs km⁻², se 3.46), a difference reflecting the amount of preferred foraging habitat (mainly pasture). Plot population densities fluctuated approximately in unison. Year-to-year density changes were strongly correlated with temperature in the preceding winter and previous year's spring/summer, indicating that warmer conditions promote both survival and breeding success. The mean spring sex ratio of sub-adults (animals born in the previous calendar year) was not significantly different from 1M:1F. However, the 1.8M:1F ratio observed for adults was significantly male biased, probably a result of female mortality associated with rearing young. The study estimates that in an average year the South Uist hedgehog population numbers c . 2750 (95% confidence limit±800) adults and sub-adults and these produce around 3000 young. Compared with the native range, hedgehog densities on South Uist are shown to be unusually high, probably because their natural predators are absent. High hedgehog densities have led directly to high rates of egg predation of ground-nesting shorebirds and subsequent declines in bird populations. The results suggest that over the past 20 years egg losses have become more severe and control of hedgehogs more difficult because climate warming has resulted in generally more favourable conditions for hedgehogs on the islands.     

Validation of a randomization procedure to assess animal habitat preferences: microhabitat use of tiger sharks in a seagrass ecosystem

1. Tiger sharks Galeocerdo cuvier are important predators in a variety of nearshore communities, including the seagrass ecosystem of Shark Bay, Western Australia. Because tiger sharks are known to influence spatial distributions of multiple prey species, it is important to understand how they use habitats at a variety of spatial scales. We used a combination of catch rates and acoustic tracking to determine tiger shark microhabitat use in Shark Bay. 2. Comparing habitat-use data from tracking against the null hypothesis of no habitat preference is hindered in Shark Bay, as elsewhere, by the difficulty of defining expected habitat use given random movement. We used randomization procedures to generate expected habitat use in the absence of habitat preference and expected habitat use differences among groups (e.g. males and females). We tested the performance of these protocols using simulated data sets with known habitat preferences. 3. The technique correctly classified sets of simulated tracks as displaying a preference or not and was a conservative test for differences in habitat preferences between subgroups of tracks (e.g. males vs. females). 4. Sharks preferred shallow habitats over deep ones, and preferred shallow edge microhabitats over shallow interior ones. The use of shallow edges likely increases encounter rates with potential prey and may have profound consequences for the dynamics of Shark Bay's seagrass ecosystem through indirect effects transmitted by grazers that are common prey of tiger sharks. 5. Females showed a greater tendency to use shallow edge microhabitats than did males; this pattern was not detected by traditional analysis techniques. 6. The randomization procedures presented here are applicable to many field studies that use tracking by allowing researchers both to determine overall habitat preferences and to identify differences in habitat use between groups within their sample.     

Weak negative associations between avian influenza virus infection and movement behaviour in a key host species,the mallard Anas platyrhynchos

Animal movements may contribute to the spread of pathogens. In the case of avian influenza virus, [migratory] birds have been suggested to play a role in the spread of some highly pathogenic strains (e.g. H5N1, H5N8), as well as their low pathogenic precursors which circulate naturally in wild birds. For a better understanding of the emergence and spread of both highly pathogenic (HPAIV) and low pathogenic avian influenza virus (LPAIV), the potential effects of LPAIVs on bird movement need to be evaluated. In a key host species, the mallard Anas platyrhynchos, we tested whether LPAIV infection status affected daily local (< 100 m) and regional (> 100 m) movements by comparing movement behaviour 1) within individuals (captured and sampled at two time points) and 2) between individuals (captured and sampled at one time point). We fitted free‐living adult males with GPS loggers throughout the autumn LPAIV infection peak, and sampled them for LPAIV infection at logger deployment and at logger removal on recapture. Within individuals, we found no association between LPAIV infection and daily local and regional movements. Among individuals, daily regional movements of LPAIV infected mallards in the last days of tracking were lower than those of non‐infected birds. Moreover, these regional movements of LPAIV infected birds were additionally reduced by poor weather conditions (i.e. increased wind and/or precipitation and lower temperatures). Local movements of LPAIV infected birds in the first days of tracking were higher when temperature decreased. Our study thus demonstrates that bird‐assisted dispersal rate of LPAIV may be lower on a regional scale than expected on the basis of the movement behaviour of non‐infected birds. Our study underlines the importance of understanding the impact of pathogen infection on host movement in order to assess its potential role in the emergence and spread of infectious diseases.     

A study of home range and movements in the hedgehog (Erinaceus europaeus)

Radio-tagged hedgehogs were studied on an area of traditionally managed farmland to obtain information about distances travelled and range areas used per night in this habitat. Data from five animals were obtained on 62 hedgehog/nights. Twelve of the data sets were eliminated owing to their incompleteness; observations of three animals (totalling 45 hedgehog/nights of acceptable data) were critically examined to establish basic procedures for future comparative studies. The concept of 'home range' is discussed in relation to the duration of study periods.     

Towed-float satellite telemetry tracks large-scale movement and habitat connectivity of myliobatid stingrays

Batoids are important mesopredators whose high mobility and extensive migrations can link seemingly distant food webs in coastal ecosystems. Despite this recognition, our knowledge of the movement patterns of many species is limited due to the logistical challenge of tracking these animals on multiple scales. Smart Positioning or Temperature (SPOT) satellite-linked transmitters allow for precise, multi-scale tracking of species that regularly use surface waters. To date, SPOTs have been predominantly used on sharks, with only a single application to a batoid. Given the epipelagic nature of myliobatid stingrays, we examined the potential for towed-float SPOT transmitters to monitor large-scale movements of two representative species: the Cownose Ray (Rhinoptera bonasus; n?=?15) and Spotted Eagle Ray (Aetobatus narinari; n?=?9). Tracking data identified several consistent outmigration patterns of Cownose Rays along the Mississippi-Alabama shelf and seasonal variation in movement rates along barrier island habitats. We also documented sex-related differences in movement rates and habitat use of Spotted Eagle Rays along the Bermuda platform, where males exhibited significantly higher movement rates than females and more transient behavior between inshore lagoons and outer coral reefs. Both Cownose and Spotted Eagle Rays were shown to exhibit connectivity among several habitat types along continental shelves in their respective locales, demonstrating future challenges to the management of these species over large spatial scales. While reductions in tag size and improved tethering techniques would undoubtedly broaden the applicability of towed-float satellite telemetry to other species and sizes, our work highlights the strong potential for this technology to provide insights into the spatial ecology and habitat use of myliobatid rays.     

Adult and hatch-year blackpoll warblers exhibit radically different regional-scale movements during post-fledging dispersal

Using a broad-scale automated telemetry array, we explored post-fledging movements of blackpoll warblers breeding in Atlantic Canada. We sought to determine the full spatial scale of post-fledging dispersal, to assess support for three hypotheses for regional-scale post-fledging movement, and to determine whether learning influenced movement during this period. We demonstrated that both young and adults moved over distances more than 200 km prior to initiating migration. Adults moved southwest, crossing the Gulf of Maine (GOM), consistent with the commencement of migration hypothesis. Hatch-year birds exhibited less directional movements constrained geographically by the GOM. Their movements were most consistent with exploration hypotheses—that young birds develop a regional-scale map to aid in habitat selection, natal dispersal and subsequent migrations.