An erosion control revetment was constructed at the Falkner Island Unit of the Stewart B. McKinney National Wildlife Refuge, Connecticut during the winter of 2000–2001. At the time, Falkner Island was the fifth largest breeding colony site for the federally endangered Roseate Tern. This study measures and describes some baseline information regarding Roseate Tern nesting, behavior, and habitat use at Falkner Island during the three breeding seasons prior to revetment construction (1998–2000). This baseline information is then compared to similar information from the first breeding season following revetment construction (2001). For Roseate Tern adults, this study examined changes in pre-nesting habitat use, nest site distributions, and pre-nesting behavioral time allocation. Changes in habitat availability and habitat use by Roseate Terns are compared as a result of the revetment construction. Roseate Terns used rocky beach in a greater proportion than other habitats before revetment construction, and used revetment boulders in a greater proportion than all other habitats after revetment construction. Roseate Terns nested more often in artificial sites (nest boxes and tires) than in natural sites in all years of the study. The mean date for the first eggs in each nest did not differ between years. We observed more Roseate Terns prospecting artificial nest sites (n = 66 times) than natural sites (n = 21 times) for three years of this study. Prospecting behavior occurred later in the season in some subcolonies, but this difference did not appear to be related to the construction. For Roseate Tern chicks, this study investigated the use of crevices as hiding places from before (1999–2000) and after (2001) the construction of an erosion control revetment. In all years, Roseate Tern chicks used crevices found under artificial nest sites more frequently than expected by chance when compared to crevices found in other microhabitats. Chicks also used crevices formed in various microhabitat types at different stages of development. The erosion control revetment created crevices that had larger openings, steeper floors, and deeper lengths than those previously used by chicks before construction. In the year after revetment construction, the openings of crevices used by chicks that died were wider than crevices used by chicks that survived. We discuss our findings in the context of the potential consequences that the revetment construction had on Roseate Tern chick survival.

No description available.

No description available.

<p>  </p> <p>Bats serve important ecological and economic roles in their communities. However, due to anthropogenic land use and human-introduced disease, bat populations in North America are facing unprecedented declines. To better inform conservation efforts for bat species in northeastern Indiana, I studied two aspects of bat ecology: (1) the effects of urbanization and agriculture on bat community composition in northeastern Indiana and (2) the roosting behavior of a population of state endangered/federally threatened northern long-eared bats (<em>Myotis septentrionalis</em>; hereafter northern myotis) in a restored mesic forest adjacent to a moderately sized city (Fort Wayne, IN). To study the first aspect, I deployed acoustic detectors in green spaces throughout Fort Wayne and the surrounding rural areas of Allen County. For each detector site, I compared species occupancy rates with site-specific characteristics at the plot scale (e.g., % canopy cover, midstory density) and at multiple landscape scales (e.g., % impervious cover within 1 km). Across 429 survey nights, acoustic detectors recorded calls from eight unique bat species, of which six species were abundant enough to conduct occupancy modeling. In four of the six species, measures of the amount of forest and forest edge in the landscape were included in one or more of the top models. The top models for the two other bat species, tricolored bats (<em>Perimyotis subflavus</em>) and silver-haired bats (<em>Lasionycteris noctivagans</em>), included measures of urban land cover and revealed a negative relationship between probability of occupancy and the proportion of high-density urban land in the area. The effect of habitat scale also differed between species. For example, models in the confidence set for eastern red bats (<em>Lasiurus borealis</em>) included variables associated with the plots surrounding detectors and with landscape features within 100 m of detectors. In contrast, the top models for hoary bats (<em>Lasiurus cinereus</em>) included landscape features at larger scales, within 500m and 1 km of detector sites. These findings suggest that both generalist and forest-obligate bat species in this study area selected spaces with greater levels of forested habitat. Furthermore, heavily urbanized areas were less likely to support the same levels of bat diversity as areas with forests and other green space.</p> <p>To accomplish the second aspect of my project, I captured bats in Fox Island County Park (Fort Wayne, IN) using mist-nets and affixed temperature-sensitive radio transmitters to four northern myotis individuals. I tracked these individuals back to day roosts, where I recorded roost characteristics (e.g., tree height, # of roost trees within 0.1 ha) and monitored bat skin temperatures (Tsk). I compared the characteristics of selected roosts to those of randomly assigned available trees in the same landscape to determine trends in roost selection preferences. Northern myotis in this study strongly preferred standing dead trees within a 31-ha patch of flooded forest on the northern border of Fox Island. These trees were highly exposed to solar radiation and were consistently warmer than ambient weather conditions, which suggests they may provide important thermoregulatory benefits to reproductive females and other members of the population.</p> <p>My research offers valuable information regarding resource use by bat communities in a landscape dominated by anthropogenic development. Urban areas containing large stretches of forests with trees in various stages of decay will be more likely to meet the needs of bats that would otherwise struggle in developed landscapes. The results of this study can be used to inform conservation efforts aimed at protecting populations of bats throughout Indiana and the Midwestern United States.</p>

Data collected during boat-based and aerial surveys were used to describe population structure, movements, temporal patterns of migration and skin condition of humpback whales in breeding sub-stock C1-S off southern Africa. Results confirmed that the migration route along the south coast of South Africa is linked to the winter ground off Mozambique. A lack of exchange between breeding sub-stocks C1-N and C1-S was found, suggesting that these are independent of each other. Molecular analysis revealed unexpected levels of population structure between the migration route and the winter ground of C1-S, as well as the possibility that this migration route is also utilised by some individuals from breeding sub-stock C3. A skin condition of unknown aetiology that primarily affects humpback whale mother-calf pairs was identified. The first assessment of its prevalence and severity was made, providing a baseline for future monitoring. Humpback whale abundance in an inshore region of Bazaruto Archipelago, Mozambique was estimated and attempts were also made to use the limited information off Plettenberg Bay/Knysna, South Africa. In addition to improving our understanding of humpback whales from Breeding Stock C, knowledge about another baleen whale species utilising the southwest Indian Ocean was extended. The first evidence of southern right whale presence off the coast of Mozambique since the cessation of whaling was documented. It remains unknown whether this is a remnant sub-stock or the recovering South African sub-stock reoccupying its historical range.

Le sanctuaire Agoa est une aire marine protégée dans la zone économique exclusive (ZEE) des Antilles françaises qui fut créée en 2010 pour la conservation des mammifères marins et de leurs habitats. Il est connu que le rorqual à bosse fréquente les eaux des Antilles de décembre à mai pour la reproduction et la mise bas. Par contre, peu d’information existe sur l’abondance, le comportement, la distribution et les pressions anthropiques sur cette espèce aux Antilles et encore moins dans le sanctuaire. Cette maîtrise s’intéresse principalement à connaître cette espèce dans un secteur précis de cette aire marine et les liens qu’elle entretient avec certains utilisateurs humains de son habitat. Le tout vise à informer les intervenants en place, autant institutionnels qu’utilisateurs, vers une mise en place de mesures de conservation adaptées. Un suivi terrestre hivernal de plus de 300 heures, en 2012 et 2013, a permis de déterminer l’utilisation de l’habitat et les pressions anthropiques sur une population de rorquals à bosse fréquentant le sud de la péninsule de la Pointe-des-Châteaux en Guadeloupe. Il s’agit du premier suivi terrestre de cette espèce aux Antilles françaises et un des premiers dans l'arc caribéen. La zone d’étude couvre environ 264 km2 et serait une des zones les plus fréquentées de l’archipel guadeloupéen par l’espèce. À l’aide d’un théodolite, la trajectoire de 107 groupes différents (137,8 heures, 699 remontées) a été décrite. Les résultats montrent que la zone d’étude est principalement fréquentée en mars et avril, avec une abondance maximale au début du mois d’avril. La forte présence de baleineaux, particulièrement au mois de mars, pousse à croire que cette zone est utilisée comme pouponnière. Le comportement n’est pas aléatoire dans la zone d’étude et les trajectoires convergent vers certaines zones ayant possiblement un lien avec la bathymétrie. De plus, la zone marine à proximité de la Pointe-des-Châteaux pourrait potentiellement être un lieu de convergence des groupes. Ceux-ci se déplacent à vitesse réduite en direction ENE en général, à l’exception des femelles accompagnées de baleineaux qui prennent une orientation tout autre, c’est-à-dire vers le ONO, et ce à plus grande vitesse. Bien que la pression d’observation soit considérée comme modérée, une forte proportion des remontées se trouve dans les corridors de navigation présents dans la zone d’étude. De plus, le corridor de navigation des navettes entre Saint-François et La Désirade comporte le plus grand risque relatif de collision mortelle. Une réduction de vitesse des embarcations fréquentant le corridor des navettes diminuerait significativement le risque de collision mortelle. Ces pistes de réflexion mèneront sans doute à d’autres études plus poussées afin de continuer à en apprendre sur l’écologie de cette espèce fascinante. / The Agoa sanctuary, a marine protected area (MPO) covering the exclusive economic zone (EEZ) in the French Caribbean, was created in 2010 to protect marine mammals and their habitats. It is known that the Caribbean islands are used from December to May by humpback whales (Megaptera novaeangliae) as a reproductive area. However, sparse information exists on the abundance, the behaviour, the distribution and the anthropogenic pressures on this species in the Caribbean and even less in the sanctuary. This thesis focuses on increasing scientific knowledge about this species’ use of a part of the Agoa Sanctuary and their interactions with human users of the MPO. Such knowledge may inform stakeholders’ (institutional and individual) decision-making towards implementation of appropriate conservation measures. A land-based survey of more than 300 hours, in 2012 and 2013, was carried out to determine the habitat use of, and anthropogenic pressures on, a population of humpback whales frequenting the surrounding water of the Pointe-des-Châteaux peninsula in Guadeloupe. This is the first land-based survey of this species in the French West Indies and one of the first in the Caribbean. The study area of approximately 264 square kilometres is one of the most visited areas by this species in the Guadeloupe archipelago. Using a theodolite, 107 trajectories (i.e. groups of whales) were recorded, representing 137.8 hours and 699 surfacings. Results show that the abundance was higher in March and April with a peak in the first week of April. The high proportion of calves in this population, mainly in March, suggest that the study zone is a nursing area. Overall movement patterns are not random and may possibly be dictated by the bathymetry. Furthermore, trajectories seem to converge close to the Pointe-des-Châteaux. The average movement is slow and oriented in the same direction as the dominant current to the west of the Pointe-des-Châteaux (i.e. ENE), except for mother and calf groups that swim faster in the opposite direction (i.e. WNW). Even if the anthropogenic pressure may be consided as moderate, a high proportion of surfacing is located in some of the main maritime traffic corridors. In addition, the shuttle corridor between Saint-Francois and Désirade island has the greatest relative risk of fatal collision. A reduced speed for the shuttle corridor would lower significantly the collision risk. These findings may lead to more extensive studies to better understand the ecology of this fascinating species.

O lobo-guará é uma espécie de ampla distribuição na América do Sul, tendo no Brasil sua maior área de ocorrência. No entanto, as modificações das áreas naturais principalmente destinadas à agropecuária tornam a espécie vulnerável à extinção. A investigação objetivou conhecer em larga escala a área de distribuição potencial gerada por atributos ambientais favoráveis e áreas adequadas à sua ocorrência nos biomas brasileiros e investigar como a espécie responde à estrutura da paisagem, avaliando os efeitos de ambientes modificados pelo homem na sua ecologia espacial, nos padrões de atividade e na movimentação. Modelos de distribuição de espécie foram gerados pelo Maxent, utilizando uma base de pontos de localização de presença a partir de 2000 para o Cerrado (Ce), Pantanal (Pa), Mata Atlântica (MA) e Pampas (Pp) e um conjunto de onze variáveis ambientais não correlacionadas (topográficas, climáticas e paisagísticas). Para análises de ecologia espacial, das atividades e de movimentação, utilizou-se localizações de telemetria (GPS) de animais habitantes de áreas protegidas (AP), e indivíduos em paisagens modificados (AM). Análises de áreas de vida (AV) foram realizadas utilizando o estimador AKDE e associadas com classificação da paisagem local. Os modelos de distribuição do lobo-guará apresentaram uma área de distribuição potencial de 78% do total dos biomas. Apesar de possuírem grandes proporções de áreas adequadas (Ce, 90%; Pa, 93%; MA, 65% e Pp, 6%), somente um pequeno percentual (4,4% do Ce e 4,7% da MA) possui adequabilidade ambiental acima de 50%. Dos atributos que favorecem sua presença, a altitude (para todos os biomas), a precipitação (Ce e Pa), diferenças de temperatura e uso e cobertura do solo (Ma e Pp) foram os mais importantes. Em nível local, animais apresentaram média de AV de 90Km2 em AP e 41Km2 em AM, uma diferença significativa (p<0,01) com áreas diretamente proporcionais ao percentual de áreas naturais na paisagem. Ainda, apesar dos padrões regulares de atividade não mostrarem grandes mudanças, o período de repouso foi significativamente maior (p<0,01) entre os animais AM (46% do dia) que em animais AP (25% do dia). Lobos-guarás de AP e AM não apresentaram grandes diferenças no deslocamento diário com média geral de 14km caminhados por dia, com comprimentos de passos de 1Km. Diferenças no comprimento de passo foram relacionadas à composição da diversidade de contato de classes da paisagem com a proporção de ambientes naturais no passo (quanto maior as variáveis, maior o passo). Passos menores refletem menor persistência de movimento interferindo no deslocamento diário. Com os resultados desse estudo identificou-se a MA e Pa muito importantes, mas o Ce como bioma mais adequado à espécie. Foram encontrados indícios de que a estrutura de suas AV, o uso da paisagem, as atividades e movimentação são afetados pela paisagem modificada. Isso pode comprometer a viabilidade populacional, interferindo na presença em uma área e refletindo no seu potencial de distribuição. As estratégias de manejo de uso do solo, e a recuperação e conexão de áreas adequadas são urgentes e necessárias para que o lobo-guará permaneça presente e funcional nas paisagens dos biomas brasileiros. / The maned wolf has an extensive distribution range throughout South America with Brazil holding the largest portion of this area. However, the species is presently under a vulnerable status due to natural habitats alteration especially from farming and ranching. This study aimed to observe in large scale the potential distribution area indicated by favorable environmental attributes and suitable habitats to its presence within the Brazilian biomes and further to investigate how the species respond to the landscape structure, evaluating the effects of human-modified landscapes on its spatial ecology, activity patterns and movements. Species distribution models were generated using Maxent with a database of presence-only locations from 2000 though 2015, of the Cerrado (Ce), Pantanal (Pa), the Atlantic Forest (AF), and the Pampas (Pp) biomes, and eleven uncorrelated environmental variables (topographic, climatic, and landscape-based). As for the spatial ecology, activity and movement analysis, GPS-based telemetry locations were used from animals inhabiting protected (PAs) and disturbed areas (DAs). Home range (HR) analysis was performed using the AKDE estimator and then associated with the landscape-classified image. The distribution models for the maned wolf showed a potential distribution area of 78% of the total biomes range. Despite the high proportion of suitable areas (Ce, 90%; Pa, 93%; AF, 65%, and Pp, 6%), only a small percentage of the biomes (4.4% for Ce and 4.7% for AF) presented values over 50% suitable. Concerning the attributes that favor its presence, the altitude (for all the biomes), the precipitation (Ce and Pa), the temperature differences and land use (AF and Pp) were the most important. At the local scale, maned wolves showed HR sizes (average) with significant differences (p<0.01) between the 90Km2 (PA) and 41Km2 (DA) with HR size directly related to the proportion of natural areas. Although the general activity patterns were not considerably different between PA and DA, the resting periods of DA\'s animals (46% of the day) were significantly different (p<0.01) than the period of PA\'s wolves (46% of the day). Animals did not show changes on the daily movement patterns, accounting with 14km in general average and 1km of average step length (no major differences as well). The variation on the step length was related to the association of the diversity of contacts between landscape classes with the proportion of natural classes at each step (as bigger the variable values, bigger the step). As a consequence of smaller steps, constancy of movement decreases. Considering the results, the AF and Pa outstand as very important biomes, however the Ce was indicated as the most suitable biome. Furthermore, the research indicated signs that the HR structure and the landscape use, besides the activity patterns and the movement are affected by altered landscapes. This might compromise the population viability, interfering directly on its presence in an area and affecting the species distribution. Thus, a proper land use management aiming the recovering of degraded habitats is an important strategy tor the maned wolf conservation, so the species can long last survive across the Brazilian biomes.

Early life stages of many marine and diadromous fish species use sandy beach surf zones, which occur along >50% of the world's marine coastlines. This extensive habitat can provide juvenile fishes with an abundant supply of potential prey and the ability to hide from predators in its shallow turbid waters. Chinook salmon is an anadromous species that migrates to the ocean during their first (subyearlings) or second (yearlings) year of life. The majority of subyearlings reside in estuaries during their first summer season; however, a small number of juveniles also use surf zones. Early marine residence is considered a critical period for Chinook salmon due to high mortality rates; however the role of surf zones in Chinook salmon life history is unclear. Therefore, I determined the distribution of juvenile Chinook salmon on beaches of the eastern North Pacific, compared the migration and growth patterns observed in surf zones and estuaries, identified the factors that accounted for variation in juvenile surf zone catch, explored the factors that influence growth rate variation in surf zones and estuaries, and modeled how growth rates in these coastal habitats may vary in the near future with predicted changes in climate. The majority (94%) of juveniles were caught in surf zones adjacent to estuaries with trough areas, which are beach sections where sand moved by currents and waves produce a trench-like shape. Surf zone fish were collected in significantly lower numbers than estuarine juveniles but entered brackish/ocean waters at similar sizes. Juveniles in surf zones consumed similar organisms (gammarid amphipods, crustacean larvae and insects) as in estuaries. Furthermore, stomach fullness indices (average = 2% of body weight) and growth rates (average = 0.4 mm day�����) were similar in surf zones and estuaries. At one surf zone, juvenile catch was positively correlated to short-term specific growth rates (14 days prior to capture). A bioenergetics modeling approach indicated that given current conditions, consumption rates accounted for more of the variation in growth than prey energetic content and temperature. Climate models predict future increases in fresh water temperature (1.5 to 5.8��C), sea surface temperature (1.2��C) and wave height (0.75 m) that could influence estuarine and surf zone use. Therefore, I developed a local mixing model based on these predictions to estimate future surf zone and estuarine water temperatures in two of the watersheds studied. Based on these temperature projections and the bioenergetics model, I predicted how juvenile specific growth rates would vary in both habitats. I determined that increases in water temperature in both habitats would reduce specific growth rates by 9 to 40% in surf zones and estuaries if diet composition and consumption rates remain similar to present conditions. To compensate for the decline in growth, juveniles may increase their consumption rates or consume more energetically rich prey, if available. If they are not able to compensate, their size at the end of the season may be reduced, which could reduce their overall survival. These results confirm that a small number of suyearling Chinook salmon use sandy beach surf zones, mostly adjacent to estuary mouths, where they experience growth conditions comparable to estuaries. My findings indicate that, in certain situations, juvenile Chinook salmon surf zone use can be influenced by surf zone growth conditions, while variation in growth rates are themselves most strongly influenced by variation in consumption rates in surf zones and estuaries. Predicted changes in coastal western North American climate will likely modify juvenile growth conditions in the next 50 years, and potentially reduce overall survival. Additional insights into the potential impacts of climate change on juvenile salmon will require estimates of changes in the composition, energetic quality and abundance of prey communities inhabiting coastal environments. / Graduation date: 2013

En la presente tesis doctoral se aborda el estudio de las comunidades de peces presentes en las zonas someras litorales del Mar Menor. La comunidad objeto de estudio estuvo conformada principalmente por individuos en estado de postlarva e individuos juveniles, junto con los adultos de especies de talla pequeña.Los objetivos planteados fueron:A) Caracterización específica de la ictiofauna.B) Análisis de la biología poblacional y relaciones con el hábitat de especies de peces bentónicos.C) Análisis de las relaciones entre los tipos de hábitats litorales y la comunidad de peces.Los resultados obtenidos ponen de manifiesto la elevada importancia de las zonas someras litorales de la laguna como hábitats esenciales para la multitud de especies ícticas, tanto aquellas que poseen interés pesquero comercial (familias Atherinidae, Mugilidae y Sparidae) como aquellas que presentan interés conservacionista (familias Cyprinodontidae y Syngnathidae). / The present PhD thesis investigates the small-sized fish assemblages in the shallow littoral areas of the Mar Menor coastal lagoon. The study was focused on juveniles of migrant fish species that recruit into the lagoon and short-lived resident fish species that spend their entire lives in it.The objectives were:A) To characterize the fish assemblages.B) To examine population biology and habitat associations of benthic fish species.C) To analyse the relationship between littoral habitat types and fish assemblages.The results pointed out the importance of shallow littoral areas of the lagoon as essential habitats for many fish species, both juvenile fish species of commercial interest (Atherinidae, Mugilidae and Sparidae families) and threatened fish species (Cyprinodontidae and Syngnathidae families).

Abstract Between October 1999 and October 2003, 30 adult and 48 young (&amp;lt; 1 year) raccoon dogs (Nyctereutes procyonoides) were monitored using radio-telemetry in an area of Germany which has been occupied by this invasive alien species since the early 1990s. Additionally, three pairs of raccoon dogs were observed by continuous radio-tracking during the first six weeks after parturition in 2003. Furthermore 136 raccoon dog pubs were ear-tagged between June 1999 and August 2006. No adult animals dispersed from the area during the study period and home ranges tended to be used for several years, probably for life. The average annual home range size, calculated using 95% fixed kernel, was 382.2 ha ± 297.4 SD for females (n = 30 seasonal home ranges) and 352.4 ha ± 313.3 SD for males (n = 32 seasonal home ranges). Paired raccoon dogs had home ranges of similar size, with pair sharing the same area all year round. Raccoon dogs occupied large core areas (85% kernel) covering 81.2% of their home ranges. The home ranges were at their smallest during the mating season. The slightly larger size of home ranges in winter suggests that, due to the temperate climate, raccoon dogs do not hibernate in Germany. Males and females formed a long-term (probably lifelong) pair bond. Same-sex neighbours ignored each other and even adjacent males/females showed neither preference nor avoidance. Thus, it can be assumed that the raccoon dog in Central Europe is monogamous without exclusive territories, based on the results of home range overlap analysis and interaction estimations. Habitat composition within home ranges and within the whole study area was almost equal. Although, percentage shares of farmland and meadow was 16.35% smaller and 12.06% higher within the home ranges, respectively. All nine habitat types (farmland, forest, settlement, water, meadows, maize fields, small woods, reeds and hedges) were used opportunistically by raccoon dogs. No significant, recognisable difference for habitat preferences between seasons was detected. Male and female raccoon dog showed equal habitat preference pattern. A comparison of active and inactive locations in different habitats found no remarkable differences. Habitat composition of individual home ranges was used to classify animals. If the percentage of forest within a home range exceeded 50% the individual was classified as a ‘forest type’ raccoon dog. If the percentage of forest habitats within a home range was less than 5%, the share of pastureland was mean 81.82% ± 16.92 SD. Consequently the individual was classified as a ‘agrarian type’ raccoon dog. Neither habitat preference nor habitat selection process differed between the two ‘types’. Habitat use and preference is discussed with relation to the ability of the raccoon dog to expand its range towards Western Europe. Males spent noticeably more time (40.5% of the time ±11.7 SD) alone with the pups than females (16.4% of the time ±8.5 SD). Females had noticeably larger 95% kernel home ranges (98.24 ha ±51.71 SD) than males (14.73 ha ±8.16 SD) and moved much longer daily distances (7,368 m ±2,015 SD) than males (4,094 m ±2,886 SD) in six weeks postpartum. The raccoon dogs being studied left the breeding den in the 6th week after the birth of the pups. In situ video observation showed that the male carried prey to the den to provide the female and the litter with food. A clear division of labour took place among parents during the period in which the pups were nursed: males guarded the litter in the den or in close vicinity of it, while the females foraged to satisfy their increased energy requirements. There were relocations of 59 (43.4%) ear-tagged young racoon dogs and mean distance from marking point was 13.5 km ±20.1 SD. Dispersal mortality rate was 69.5% among young raccoon dogs. Most animals (55.9%) were recovered nearer than 5 km from the marking point, whereas only 8.5% relocations were recorded further than 50 km from the marking point. There was no difference in the distances of relocations between sexes. Most (53.7%) relocations of ear-tagged young raccoon dogs were in August and September and, only 34.1% were recorded from October to April. Hunting (55 %) and traffic (27 %) were the major mortality factors. Radio-collared young raccoon dogs generally dispersed between July and September. The mean natal home range size (MCP 100%) with and without excursions was 502.6 ha ±66.4 SD (n = 9) and 92.1 ha ±66.4 SD (n = 17), respectively. There were no differences between sexes in the month of dispersal. The direction of travel for dispersing animals appeared to be random, with distances from 0.5 km to 91.2 km. A highly flexible dispersing behaviour is certainly one of the reasons which contribute to the high expansion success of the species.