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.     

Dung beetle movements at two spatial scales

To understand the dynamics of spatially structured populations, we need to know the level of movements at different spatial scales. This paper reports on Aphodius dung beetle movements at two scales: movements between dung pats within pastures, and movements between pastures. First, I test an assumption common to many recent models of spatially structured populations – that the probability of an individual moving between habitat patches decreases exponentially with distance. For dung beetles, I find sufficient evidence to reject this assumption. The distribution of dispersal distances was clearly leptokurtic, with more individuals moving short and long distances than expected on the basis of an exponential function. In contrast, the data were well described by a power function. I conclude that dung beetle movements include an element of non-randomness not captured by the simplistic exponential model. The power function offers a promising alternative, but the actual mechanisms behind the pattern need to be clarified. Second, I compare several species of Aphodius to each other. Although these species occur in the same network of habitat patches, their movement patterns are different enough to result in a mixture of different spatial population structures. Movements between pastures were more frequent the larger the species, the more specific its occurrence in relation to pat age, and the more specialized it is on cow dung and open pasture habitats. Within pastures, all species form "patchy" populations, with much movement among individual pats.     

Pattern of movements of adult Barbus haasi in a small Mediterranean stream

Most adult Barbus haasi , at a 1950 m-long site in Vallvidrera creek, were highly sedentary and resided within a home range <20 m (32 m²), while a small group were more mobile. On successive sampling occasions, between 52·3 and 64·9% of fish were recaptured in the same 10-m-long section in which they had previously been captured. Movements over long distances were infrequent, and only 5·6% of the fish moved >100 m. The movement pattern of the population was seasonally stable, although the mean distances were slightly greater in summer because of the medium-range movements of a few individuals. Overall, upstream and downstream movements were equally common but a significant downstream movement occurred in spring. The size of the fish did not influence the movement rate. Fish inhabiting those sections of the stream with greater depth, slower current and more cover had a lower movement rate than fish occupying shallower, exposed sections. The restricted movement of B. haasi could increase the survival of fish by increasing the probability of staying in the remaining pools during summer dry-out, and may therefore be of adaptive significance.     

The spatial population dynamics of insects exploiting a patchy food resource

The population dynamics of ten species of phytophagous insects and seven parasitoids inhabiting the flowerheads of two herbaceous plants, Centaurea nigra and Arctium minus, were studied, and three main aspects of their ecology were examined, namely, rates of population extinction, density dependence in population changes from one generation to the next, and movements between populations. The study was based on monitoring the insect populations on more than 50 patches of each plant, scattered over 5 km² of arable farmland and the results were used to test the relative importance of immigration and population regulation to the persistence of these populations. This paper describes the study of movements between patches of food plant. Experimentally planted new patches of plants were rapidly colonised by all species and this appeared to be unaffected by distance from a source population, up to the maximum distance of 800 m considered in the experiment. Large patches tended to be colonised more readily than small ones. Movements between plant patches were studied with the use of chemical markers (Rb, Sr, Dy and Cs) which were applied as chloride salts to individual patches, and which were translocated to the flowerheads and so to insects feeding on the seed, and to their parasitoids. Initial experiments in the laboratory showed that these elements could be readily detected by ICP (Inductively Coupled Plasma) mass spectrometry in the bodies of all species reared on potted plants sprayed with solutions containing them. Background levels of strontium were patchily high on the study area, but the other elements were naturally either absent or in very low concentrations. Four patches of each plant were marked with a different element in 1991. In 1992, samples of four species of tephritid fly and two parasitoids were collected from all patches, and analysed for the four elements. These analyses showed that individual of all species moved considerable distances, with movements of up to 2 km being commonly recorded. Estimates of rates of immigration to patches showed that movement plays an important role in the population dynamics of these insects. There was some evidence that immigration was density-dependent: it was highest when the resident populations (numbers per flowerhead) were low.     

Comparative study on the consequences of culling badgers (Meles meles) on biometrics, population dynamics and movement

1.  Capture–mark–recapture data were used to describe the process of recovery from a typical badger removal operation (BRO) at North Nibley, Gloucestershire, UK, which was carried out as part of the government's strategy to control bovine tuberculosis. Data on biometrics, demographics and movement from this low-density disturbed population were compared with those of two nearby high-density undisturbed populations (Wytham Woods and Woodchester Park, UK) in order to study fundamental principles of population dynamics and density-dependence.
2.  Badgers moved more between social groups at North Nibley than in the other study areas, particularly in the immediate aftermath of the removal operation.
3.  Recolonization of the vacated habitat occurred in the first instance by young females.
4.  Although in the first year after the BRO no cubs had been reared in any of the culled groups, and although the shortage of sexually mature boars may have limited the reproductive output of sows in the following year, the population took only 3 years to recover to its (already lowered) preremoval density.
5.  Losses from the adult (and cub) population due to mortality or emigration were smaller at North Nibley than at the other sites.
6.  There was much evidence that during 1995 and 1996 density-dependent effects constrained the reproductive output of the high-density populations, and some support for the hypothesis that badgers exhibit the non-linear 'large mammal' type of functional response to density.
7.  Badgers at North Nibley were younger, heavier and in better condition than badgers at Wytham Woods and Woodchester Park.
8.  We argue that the disease dynamics are likely to be different in disturbed compared with undisturbed badger populations, and that this could affect the effectiveness of BROs.     

Migration and Allee effects in the six-spot burnet moth Zygaena filipendulae

Abstract 1. Migration into local populations may increase the likelihood of persistence but emigration may decrease the persistence of small and isolated populations. The dispersal behaviour of a day-flying moth Zygaena filipendulae was examined to determine whether emigration is correlated positively or negatively with population size and host plant density.
2. A mark–release–recapture study showed that most moths moved small distances (< 40 m on average) and only 6% of movements were > 100 m.
3. Twenty-five individuals moved between populations, a measured exchange rate of 8%. Moths were more likely to move between patches that were close together and they moved to relatively large patches.
4. The fraction of residents increased with increasing population size in the patch and increasing host plant cover. Relatively high proportions of individuals left small patches with small moth populations.
5. Moths released in grassland lacking Lotus corniculatus (the host plant) tended to leave the area and biased their movement towards host plant areas, whereas those released within an area containing L. corniculatus tended to stay in that area.
6. Biased movement away from small populations and areas of low host plant density (normally with low population density) was found. This migration-mediated Allee effect is likely to decrease patch occupancy in metapopulations, the opposite of the rescue effect. The effects on metapopulation persistence are not known.     

Movements of the flying squirrel Pteromys volans in corridors and in matrix habitat

Elements of the landscape, such as patches of preferred habitat, matrix between patches, and corridors linking patches, differ as movement habitat for animals. To understand how landscape structure influences the movement and thus, population dynamics of animals, clear empirical knowledge on patterns of movement is needed. The Siberian flying squirrel inhabits spruce-dominated boreal forests from Finland to eastern Siberia. Numbers of flying squirrels have declined severely in Finland in past decades, probably due to modern forestry. We studied the movement of radio-collared adult flying squirrels in preferred (spruce forest) and in matrix habitat (open areas and other habitats with trees) in Finland 1997–2000, and determined whether the woodland strips connecting patches of preferred habitat could function as ecological corridors for flying squirrels.
Flying squirrels used woodland strips for inter-patch movements, but also used matrix with trees and were able to cross narrow open gaps. Males moved longer total distances and crossed edges more often than females. Males used matrix habitats for movement between spruce patches, and moved faster and more directly in the matrix than in the spruce forest. Females seldom changed spruce patches, but instead used the matrix for foraging. For both sexes probability of leaving the spruce forest patch correlated negatively with the size of the patch, but the type of connection the patch had to other patches did not affect the leaving probability. Due to efficient movement abilities of the flying squirrel and forest-dominated landscape structure of southern Finland, we suggest that conservation acts for maintaining viable populations of flying squirrels should focus on the quality of managed forest and the area of suitable breeding habitat (i.e. on habitat loss), but not necessarily on ecological corridors.     

Evidence of climate change effects on within‐winter movements of European Mallards Anas platyrhynchos

Other than during periods of migration, animal movement tends to be poorly described, despite the potential importance of such movements, which may prove crucial for surviving periods of bad weather and low food availability. We analysed within‐winter (December–February) movements of Mallard using the EURING Data Bank. Most movements were directed towards the south or southwest during all three winter months. Distances covered increased with winter harshness and generally decreased from 1952 to 2004. Mallards appear to move less than other duck species during winter. Long‐distance movements of Mallards seem to be related to cold weather, birds only moving long distances in large numbers during the very coldest winters. Movements are not restricted during midwinter, but occur throughout the winter. The decreasing within‐winter movement over time (1952–2004) could be explained by decreasing reporting probabilities and/or warmer winters in recent decades. However, the first is only true if the decrease in reporting probability increases with distance moved, for which we found no indication in our study. Therefore, we suggest that the pattern found is evidence of long‐term winter warming reducing the distance of within‐winter movements in this species.     

Natal dispersal in relation to population density and sex ratio in the field vole,Microtus agrestis

Summary In a sample of 240 juvenile field voles 8% of the males and 22% of the females reached sexual maturity within their natal home range. Among individuals retrapped as adults, 58% of males and 23% of females had dispersed, i.e. had moved more than one home range diameter. The mean distance moved for males (58.5 m) exceeded that for females (28.6 m). Male movement distances were negatively associated with total density, and with density of adult females, but not with male density. Female movements were not related to population density. There were no relation between sex ratio and distance moved. The distribution of distances moved for both males and females fit a geometrical distribution, suggesting the importance of competitive processes.     

FOLLOWING THE THREAD TO OAK SPRING: THE AFTERLIFE OF JOHN BRADBY BLAKE'S CANTON DRAWINGS

For more than 175 years, the remarkable botanical drawings made in Canton by a Chinese artist working with the British East India Company supercargo John Bradby Blake, were handed down from generation to generation within the same family. They first appeared publicly in 1959 when the estate of Sir Frederick Cripps of Ampney Park, Gloucestershire, came up for auction. A Bristol art dealer bought the drawings, but on the other side of the Atlantic, Paul Mellon had other ideas for them. This article follows the trail from London, via Ampney Park and Bristol, to Oak Spring, Virginia.     

The role of the Badger (Meles meles) in rabies epizootiology and the implications for Great Britain

The occurrence of a wildlife rabies epizootic in Britain remains a very unlikely event, but it is important to examine all the possible consequences of such an event. Here, I examine the possible role of the European Badger (Meles meles) in such an epizootic. The population density of Badgers in Britain is much higher than that in Europe, and appears to have increased substantially over the last decade or so. The population parameters and epizootiology of rabies in the Badger are reviewed in comparison with the Fox (Vulpes vulpes) and other species. Mustelids appear to be very susceptible to rabies, with the smaller mustelids becoming aggressive, although Badgers do not appear to show heightened aggression when infected. Badger populations on the continent become severely reduced when rabies arrives in the area, and circumstantial evidence strongly suggests that Badgers can easily transmit the virus. Preliminary models support the idea that the Badger could be a very significant secondary host, especially in the initial rabies outbreak. The population recovery rate of the Badger suggests that it is unlikely to become a primary host, although short‐term epizootics in the Badger population are likely. The potential for controlling rabies in the Badger is also examined.     

Low genetic variability, female-biased dispersal and high movement rates in an urban population of Eurasian badgers Meles meles

1. Urban and rural populations of animals can differ in their behaviour, both in order to meet their ecological requirements and due to the constraints imposed by different environments. The study of urban populations can therefore offer useful insights into the behavioural flexibility of a species as a whole, as well as indicating how the species in question adapts to a specifically urban environment. 2. The genetic structure of a population can provide information about social structure and movement patterns that is difficult to obtain by other means. Using non-invasively collected hair samples, we estimated the population size of Eurasian badgers Meles meles in the city of Brighton, England, and calculated population-specific parameters of genetic variability and sex-specific rates of outbreeding and dispersal. 3. Population density was high in the context of badger densities reported throughout their range. This was due to a high density of social groups rather than large numbers of individuals per group. 4. The allelic richness of the population was low compared with other British populations. However, the rate of extra-group paternity and the relatively frequent (mainly temporary) intergroup movements suggest that, on a local scale, the population was outbred. Although members of both sexes visited other groups, there was a trend for more females to make intergroup movements. 5. The results reveal that urban badgers can achieve high densities and suggest that while some population parameters are similar between urban and rural populations, the frequency of intergroup movements is higher among urban badgers. In a wider context, these results demonstrate the ability of non-invasive genetic sampling to provide information about the population density, social structure and behaviour of urban wildlife.     

Restricted movement by mottled sculpin (pisces: cottidae) in a southern Appalachian stream

1. We used direct observation and mark‐recapture techniques to quantify movements by mottled sculpins (Cottus bairdi) in a 1 km segment of Shope Fork in western North Carolina. Our objectives were to: (i) quantify the overall rate of sculpin movement, (ii) assess variation in movement among years, individuals, and sculpin size classes, (iii) relate movement to variation in stream flow and population size structure, and (iv) quantify relationships between movement and individual growth rates. 2. Movements were very restricted: median and mean movement distances for all sculpin size classes over a 45 day period were 1.3 and 4.4 m respectively. Nevertheless, there was a high degree of intrapopulation and temporal variation in sculpin movement. Movement of juveniles increased with discharge and with the density of large adults. Movement by small and large adults was not influenced by stream flow, but large adults where more mobile when their own density was high. Finally, there were differences in the growth rates of mobile and sedentary sculpins. Mobile juveniles grew faster than sedentary individuals under conditions of low flow and high density of large adults, whereas adults exhibited the opposite pattern. 3. Our results support the hypothesis that juvenile movement and growth is influenced by both intraspecific interactions with adults and stream flow. In contrast, adult movement appears to be influenced by competitive interactions among residents for suitable space. The relationship between movement and growth may provide a negative feedback mechanism regulating mottled sculpin populations in this system.     

Inter-Tributary Movements by Resident Salmonids across a Boreal Riverscape

Stream-dwelling fishes inhabit river networks where resources are distributed heterogeneously across space and time. Current theory emphasizes that fishes often perform large-scale movements among habitat patches for reproduction and seeking refugia, but assumes that fish are relatively sedentary during growth phases of their life cycle. Using stationary passive integrated transponder (PIT)-tag antennas and snorkel surveys, we assessed the individual and population level movement patterns of two species of fish across a network of tributaries within the Wood River basin in southwestern Alaska where summer foraging opportunities vary substantially among streams, seasons, and years. Across two years, Arctic grayling (Thymallus arcticus) and rainbow trout (Oncorhynchus mykiss) exhibited kilometer-scale movements among streams during the summer growing season. Although we monitored movements at a small fraction of all tributaries used by grayling and rainbow trout, approximately 50% of individuals moved among two or more streams separated by at least 7 km within a single summer. Movements were concentrated in June and July, and subsided by early August. The decline in movements coincided with spawning by anadromous sockeye salmon, which offer a high-quality resource pulse of food to resident species. Inter-stream movements may represent prospecting behavior as individuals seek out the most profitable foraging opportunities that are patchily distributed across space and time. Our results highlight that large-scale movements may not only be necessary for individuals to fulfill their life-cycle, but also to exploit heterogeneously spaced trophic resources. Therefore, habitat fragmentation and homogenization may have strong, but currently undescribed, ecological effects on the access to critical food resources in stream-dwelling fish populations.     

Moving Day and Night: Highly Labile Diel Activity Patterns in a Tropical Snake

Most animals have well established diel activity patterns (e.g., diurnal, crepuscular, or nocturnal), and changes in behavior from diurnal to nocturnal are rare in single species. We radio tracked 50 keelback snakes in a single population, locating them up to four times a day, over five periods of the year in the Australian dry tropics to describe temporal variation in diel movement patterns. Snake body temperatures were also recorded to determine the relationship between activity patterns and body temperatures. Season influenced diel activity patterns significantly. Keelbacks were more likely to move, and moved further in the daytime in the mid‐dry (June–July), and late dry (Aug–Sep) seasons. In the mid‐dry season, 87 percent of movements were diurnal, whereas in the mid‐wet (Feb–March) season, although snakes were much more likely to move, only 43 percent of movements were diurnal. In the late dry season, snakes were slightly more likely to move at night than at any other time of day, and so at this time of the year, snakes could be classified as nocturnal. Thus, overall increased movements in the mid‐wet season (austral summer) were associated with more crepuscular and nocturnal movement. There was a significant relationship between individual snake body temperatures and movement rates in all seasons. Changes in movement patterns may be related to body temperature, and this diurnal species becomes cathemeral in the tropics in summer, when it is possible to maintain high body temperatures both day and night.     

Foraging behaviour and home-range utilization in a suburban Badger (Meles tneles) population

The size and distribution of home ranges, and the dispersion of latrines, was investigated to describe the use of space and degree of territoriality within a population of Badgers ( Meles meles ) living in the suburbs of Bristol. The movement patterns of different age and sex classes were studied, along with seasonal changes in various measures of activity. Part of the study area was surveyed in detail to compare the Badger's use of space with a variety of habitat parameters, and to examine the predictability of their foraging behaviour. Many of the results are in contrast to earlier studies on rural Badgers. Range sizes were variable, and inconsistent over time, many group ranges were not contiguous and those that were overlapped. Territorial boundaries were not obvious and latrines were clumped around sett sites. Age- and sex-specific differences in movement activity were observed, along with an expansion of ranges in spring and a decrease in all forms of activity over the winter. Using multiple regression analysis, it was not easy to predict the foraging behaviour of suburban Badgers on the basis of 37 habitat variables sampled. There was some evidence of more structured foraging in the autumn, when more predictable food resources were available. The relevance of these observations to other studies on the ecology of Badger populations at varying densities and in different habitats is discussed.     

Spatio-temporal dynamics in waterbirds during the non-breeding season: Effects of local movements,migration and weather are monthly,not yearly

Predicting population sizes and dynamics of mobile organisms is important for trend estimation, but this is difficult when the origin of individuals cannot be determined, i.e. residents and migrants are indistinguishable in the field.Here we examine fluctuations in populations during the non-breeding season (autumn to spring) of seven waterbird species, which co-occur on 122 neighbouring water bodies in south-west Germany. We asked whether site-level abundance patterns can be predicted by weather variables, and whether these effects vary over months and years. We used a spatially explicit hidden Markov model to estimate the effects of local and regional movement on population fluctuations.Although the species varied in their dynamics, with different amounts of movement estimated between sites, several patterns were common across species: density effects were highly month-specific, but with little variation in the strength of effects over years. The abundance of most species was positively related to temperature, especially in winter.The common teal Anas crecca and common pochard Aythya ferina were the most site-fidelic species once they were present in the study area, but also exhibited the strongest regional migration. The mallard Anas platyrhynchos, tufted duck Aythya fuligula and great crested grebe Podiceps cristatus each behaved more like a single population, as individuals more frequently moved between sites and abundance fluctuations at sites were not explained by migratory movements alone.Our study shows that the strength of population parameters and environmental forces can be decomposed into monthly and yearly effects. Estimating the unknown origin and movement of individuals may show that commensurate populations of mobile species may have different underlying dynamics, while responding similarly to environmental factors.     

DIFFERENTIAL MOVEMENTS BY HARBOR SEAL PUPS IN CONTRASTING ALASKA ENVIRONMENTS

Movement patterns of Alaska harbor seal pups were studied using satellite telemetry during 1997–2000. Mean tracking duration was 277.3 d (SD = 105.8) for Tugidak Island pups ( n = 26) and 171.2 d (108.3) for Prince William Sound (PWS) pups ( n = 27). Movements were similar for males and females and were largely restricted to the continental shelf. Multiple return trips of > 75 km from the natal area and up to ∼3 wk duration were most common, followed by movements restricted to <25 km from the natal area; one way movements from the natal site were rare. Distances moved and home range sizes remained relatively stable or increased gradually from July through winter, then decreased markedly through spring. Monthly movements (maximum distance from tagging location, mean distance from haul-outs to at-sea locations, and home range size) were significantly greater for Tugidak vs . PWS pups. Six of seven pups from each region that traveled farthest and were tracked the longest had returned to their tagging site when their last location was recorded, indicating philopatry or limited dispersal during their first year of life. Seal pups exhibited similar movement patterns in the distinct habitats of the two regions, but differed in the spatial extent of their movements.     

Dispersal in the Glanville fritillary butterfly in fragmented versus continuous landscapes: comparison between three methods

1. Habitat fragmentation may lead to natural selection on dispersal rate and other life‐history traits. Both theoretical analyses and empirical studies suggest that habitat fragmentation may select either for increased or decreased dispersal depending on the traits of the species and the characteristics of the landscape. 2. Dispersal and movement rates in Glanville fritillary butterflies (Melitaea cinxia) originating from a continuous landscape in China and from a highly fragmented landscape in Finland were compared using three different methods. 3. The methods included replicated mark‐release‐recapture (MRR) experiments conducted in the natural environments in China and Finland, tracking with harmonic radar of captive‐reared but free‐flying butterflies in a common environment in the field, and replicated common garden experiments in a large outdoor population cage. 4. The results were largely consistent, showing that butterflies from the more continuous landscape in China had a lower movement rate than butterflies originating from the fragmented landscape in Finland. Butterflies originating from newly‐established populations in Finland moved significantly longer distances than butterflies originating from old populations in Finland or from China, demonstrating significant intra‐specific variation in dispersal rate in Finland. These results are consistent with model predictions for the Glanville fritillary. 5. The tracking experiment revealed a result that would have been impossible to obtain with MRR experiments: movement rate was influenced by a significant interaction between population origin (China vs. Finland) and ambient air temperature.